While I seriously doubt whether climate skeptics will thank me for pointing it out, I don’t believe their arguments impress the swing voters in the climate debate as convincingly as they might. With this in mind I’d like to propose a strengthening of the skeptic argument that downward longwave radiation or DLR, popularly called back radiation, cannot be held responsible for warming the surface of the Earth.
On a clear summer day, when the surface temperature is 20 °C (as it is outside my house this morning), the atmosphere is below freezing at all altitudes above 2 km, based on a lapse rate of 10 °C/km. That is, 70% of the air above is colder than a block of ice. When I measure the DLR by pointing my Microtemp MT250 infrared thermometer at the sky it registers 20 degrees below zero, icy indeed and corresponding to 2.534 * 5.67 = 232 W/m2 of DLR. Pointing it at the ground, it registers 20 °C or 2.934 * 5.67 = 418 W/m2 of upwards longwave radiation.
Meteorologists tell us that this block of ice overhead warms the ground. Well known meteorologist Alistair Fraser, who taught meteorology at Penn State from 1978 to 2001 (CV at http://www.ems.psu.edu/~fraser/cv/ ), puts it this way at http://www.ems.psu.edu/~fraser/Bad/BadGreenhouse.html :
“The surface of the Earth is warmer than it would be in the absence of an atmosphere because it receives energy from two sources: the Sun and the atmosphere. The atmosphere emits radiation for the same reason the Sun does: each has a finite temperature. So, just as one would be warmer by sitting beside two fireplaces than one would have been if one fireplace were extinguished, so, one is warmer by receiving radiation from both the Sun and the atmosphere than one would be if there were no atmosphere. Curiously, the surface of the Earth receives nearly twice as much energy from the atmosphere as it does from the Sun.”
Now if you sit beside a block of ice, does it make any sense whatsoever to say that the block of ice is warming you? Obviously it cools you, and you’re warming the ice, not the other way round.
The counterargument would be that the ice block, as a black body at 0 °C, is radiating 2.734 * 5.67 = 315 W/m2 towards you. But that’s just a number, what does it actually mean as a physical phenomenon? Well, moving the ice further away reduces its cooling effect on you and your warming effect on it, so presumably that number must be reconciled with the evident fact that you’re warming the ice, not vice versa.
Thinking perhaps that Professor Fraser’s remarkable statement would have elicited at least one objection, I searched the web for references to his website. I found a great many praising him for the clarity with which he explained global warming, but not a single objection to his claim that the atmosphere warms the surface.
On that basis it seems safe to assume that the proposition “the atmosphere warms the surface” has been assimilated and accepted by the non-skeptical public as an axiom about global warming.
So what’s going on here? In particular what is the basis for Professor Fraser’s seemingly extraordinary claim that an aerial object significantly colder than a block of ice supplies twice as much energy to the surface as the 5700 K Sun? Could it really be so, or is this just misleading numerological prestidigitation?
While Fraser does not supply a reference at that page, one need not look far to confirm this factor of two. Figure 7 of the famous 1997 paper of Kiehl and Trenberth shows the Earth’s surface receiving 168 W/m2 from the Sun and 324 W/m2 from the atmosphere.
At this point let me digress with a popular skeptic argument about net CO2 fluxes into the atmosphere. Consulting any figure depicting the carbon cycle, http://earthobservatory.nasa.gov/Features/CarbonCycle/ for example, we see that, of the 220 GtC (gigatonnes of carbon) or so being emitted annually into the atmosphere, only about 9 GtC or 4% is of anthropogenic origin. Evidently our contribution is negligible compared to nature’s. What’s the big deal?
The problem with this argument is that the CO2 flux is bi-directional, and it is the net flux that matters. Preindustrially this flux was in balance and CO2 was not under any great pressure to change rapidly in a single century (though over millions of centuries it has certainly drifted greatly).
The problem with that “small” 4% we’re adding is that, unlike nature, we’re not taking it back out! Hence that 4% is accumulating, as we can see from the Keeling curve, which shows atmospheric CO2 rising at about 2.3 ppmv these days. That 2.3 ppmv per year represents roughly half of our 4% contribution; nature has stepped up her own removal program and is busy removing the other half of the 4% as we speak.
Back to Professor Fraser’s claim. Well, what do you know, the exact same fallacy. At the same time as 324 W/m2 is entering the surface from the atmosphere, 390 W/m2 is leaving the surface. The net flux is 66 W/m2 upwards. The atmosphere is not warming the surface, it’s cooling it!
But this should have been obvious when I pointed my IR thermometer at the sky and the ground and observed 232 W/m2 down and 418 W/m2 up, a net flux of 186 W/m2 cooling the surface. On a cloudy day the sky might be 13 °C or 2.864 * 5.67 = 379 W/m2, a mere 39 W/m2 less than the radiation from the 20 °C ground. And at night a cloudy atmosphere may even occasionally warm a slightly cooler Earth. So an annual global average of 66 W/m2 upwards may well be the case, but that’s still cooling.
Experienced meteorology professor Alistair Fraser says the atmosphere warms the surface. I, an amateur hack in this area with no meteorological credentials at all, say the surface warms the atmosphere, and moreover at an average power density of 66 W/m2 and sometimes hitting upwards of 200 W/m2. Who’s to be believed?
Judging from the many favorable references on the web to his website, it is clear that Fraser has persuaded the public of the correctness of his argument. His reasoning is just as plausible as the 4% argument about CO2 made by the other side, and he taught the subject for nearly quarter of a century, so one would have to be firmly wedded to the skeptic position to object to his website.
Those who’ve thought long and hard about whether back radiation makes sense may well have arrived at the conclusion that it doesn’t. Furthermore even if they can’t articulate their conclusion with the force they would like, it may nevertheless seem intuitively clear and irrefutable to them.
What we have here is a failure to communicate. If climate science has any expectation of being able to communicate with the skeptic community, I don’t think shooting down skeptic arguments on the ground that they’re obviously weak is the way to go about it. You’ll get nowhere attacking what skeptics say, you have to address what they’re thinking, which may be based on sounder intuition than is expressed in their arguments.
Which is tough to do if they have a harder time articulating exactly what they see wrong about back radiation than seeing intuitively that the atmosphere cools the surface. To them it is totally unreasonable to view the atmosphere as warming the surface, and they find it very frustrating not being able to explain to the satisfaction of the non-skeptics what they find unreasonable about it.
Hopefully I’ve made skeptical thinking a little clearer here, at least as it bears on the back radiation concept. If this were to help the two sides to focus on their real differences instead of getting off on irrelevant tangents to do with their communication difficulties and incompatible thought processes I’d be thrilled.
Just to clarify my own position, it is clear to me, based solely on the temperature and CO2 records to date, that if CO2 continues on its present course it will reach between 850 and 1000 ppmv by 2100, by which time temperatures worldwide will have increased some 2 °C. The concept of back radiation does not enter into my projections, and I have no idea how I would use it for forecasting climate change. I’ve been unable to persuade myself that back radiation is anything more than a computationally unusable extrapolation from John Tyndall’s insightful experiments in the 1850s.
Sitting near a block of ice at ) degrees C may cool you, but sitting near a block of a substance at -270 C would cool you even more.
The cold atmosphere warms the earth, when compared with the alternative of approximate 4K space.
Ok, this may be a shock to you, but this is the first time I’ve heard “vacuum” be referred metaphorically as a “block of a substance at -270C”.
The basic problem seems to be that the author is confusing radiation with conduction and convection, etc.
Yes, that is exactly the error that Vaughan Pratt is making. The whole article is ridiculously unphysical. The *temperature* of the atmosphere at 2000m, as measured by radiation *from* the atmosphere above him, does not suck up more upward infrared, aka outgoing longwave radiation! Different comparisons can make it *seem* to be “small” but there is no denying back radiation. Or at least, there is no scientifically literate denial of back radiation.
For there to be *no* back radiation, which is his claim, his “Microtemp MT250 infrared thermometer” would need to have measured absolute zero, aka 0K, aka -273.15°C, when pointed upward. It did not. Downward longwave radiation is thus *confirmed* by his own results, which he ignorantly interprets to mean the opposite.
Hilarious.
PS Dr. Curry, how much undergraduate physics would I have to *forget* in order to be invited to ‘blog for you?
Sometimes I wonder, whether my browser shows the same article that another commenter has read.
Perhaps I cannot read Vaughan’s article similarly with others, who have not read his comments earlier this year, but I’m sure that you have read something that he doesn’t mean.
After a second reading, it does seem that he was presenting a denialist argument that is not his own view. I had never read Pratt before and assumed that all the opinions he was expressing were his own. But that doesn’t change my reaction much, because denial of back radiation is such an awkward example to use to illustrate Skepticism. It’s actually an example of denial.
There is no rational basis to dispute it, and people who would “think” like Pratt’s example don’t know conduction from radiation. They need to stop lecturing the pros based on junk they “learned” passively from watching teevee or worse, listening to conservative talk radio, and start to *ask* “what am I missing?”
That’s the real problem with the public understanding of climate science, and having the best climate scientists dumb everything down until high school dropouts can “get it” won’t solve that problem. So okay, Pratt knows that’s junk science. I still see no value in imagining that hacks doing junk science will come round, if only the competent professionals would communicate better.
Other industrial nations, where learning and achievement other than amassing wealth are generally respected, do not have this problem with disbelief in the basic, settled underlying theory of anthropogenic climate change. It is not a scientific problem, it is a cultural problem and only undercutting the cultural validity of being an obstinate idiot will solve this problem.
settledscience,
I just wanted to commend you on your cleverly conceived moniker. It gives your comments that intangible splash of sincerity they might otherwise lack.
Andrew
Settled, your diatribe is no substitute for reasoned argument. You are wasting our time. Feel free to join the debate at some point.
The presence of passion does not necessarily mean the absence of reason. It’s admittedly less sophisticated, and much less detailed, than Pratt’s essay, but I did present a reasoned argument.
I present a well-reasoned argument that anybody who concludes from that measurement of 232 W/m2 of DLR that there is no such thing as DLR, colloquially known as “back radiation,” is ignorant enough that they need to be asking questions, not making ANY assertions; and if such a person uses such crude methods to presume that all the leading experts are wrong, then that’s a presumptuous unteachable scientific illiterate who is not entitled to be the purpose of scientists’ efforts.
I realize that’s your target audience and this truth is likely to hurt you, but that is your own fault for taking the side opposite the truth, David.
Another arrogant, “smartest person in the room” wannabe warmist expert. What is it about leftist culture in particular that thinks this would be accepted as a personna?
“the side opposite of the truth”???
It’s a joke post right?
“The presence of passion does not necessarily mean the absence of reason.”
In your case it probably does.
Andrew
@cwon1
I did not say I was smarter than you. You inferred that yourself.
I will leave your inferential skill for others here to judge. Good day, sir.
PS It’s no joke. DLR is Settled Science, and nobody who says otherwise has any right to expect to be taken seriously. I find Vaughan Pratt’s approach terribly flawed, in that it systematically wastes the time of the best scientists, in servitude to folk too ignorant to inform themselves and too arrogant to admit their egregious ignorance.
Settled, you present no argument, just a measurement, known already to all. If this simple measurement settled the issue we would not have 3000 comments and counting on this topic. What is your reasoned argument?
If you re-read the original article, the subject is not the science but rather the communication skills of skeptics and faithful – not a good term but they are generally no better trained or informed than their debate opponents; maybe we should call the skeptics ‘heretics.’ As long as each side persists in misdirected argumentation, no discussion takes place. The author noted that a “skeptical” view may be the result of an intuitive judgement that is not presented in a well-framed argument (presumably not couched in the accepted jargon of the discipline). He demonstrates this several times himself. This semantic confusion _started_ historically with the misuse of the term “greenhouse” to describe how the atmosphere and oceans mediate the diurnal swing of temperature on the planet. Since it was experimentally shown before 1910 that the atmosphere and a greenhouse achieve their effects in physically, and mechanically distinct fashions, the word “greenhouse” should have vanished from the climatological lexicon long ago. The fact that it didn’t can appear _intuitively_ to a critical thinker as if the users of the word are actually ignorant of physics and thermodynamics. That in turn can lead to a blanket distrust of anyone who does use the term seriously.
In reality, the vast majority of scientifically trained heretics and faithful are not arguing over anything but details of how the system may actually work, given their _common_ assumptions are correct. They (heretics and faithful) effectively agree on the basic tenets, but the devil is in the details, magnitudes and signs of the interactions. Even Postma’s critique is little more than an appeal to apply Occam’s Razor to the issue and insure that the science applied on earth is equally applicable on Mars and Venus (it is not otherwise science) and to avoid applying overly-simple simplifying assumptions to models – e.g. 1/4 uniform radiation as opposed to a proper day-night cycle.
Equally, it is clear to anyone trained in geology that the natural catastrophes prophesied by the faithful are empirical nonsense. The planet has already been (as far as CO2 goes) there and far beyond. This is as much a fact as DLR is a fact. It is also a fact that no natural catastrophes have ensued. At the same time, while the heretics may comfort themselves with this, there is reason to argue that regional anthropogenic effects may very well lead to social catastrophes. Small changes weather patterns driven by regional anthropic effects that the planet and the biosphere will shrug off easily could very well effectively destroy the subsistence bases for many people.
@Duster
Thanks, I got that last week, from Pekka Pirilä.
I disagree with absolutely everything you say after that observation of something that had already been pointed out to me, and which I already acknowledged.
That’s demonstrably wrong.
http://www.pnas.org/content/early/2010/06/04/1003187107.abstract
Forget about your amateur opinions about climate science, and forget about my amateur opinions. Within the field of legitimate experts — which by definition is the professionals publishing research in the field of climate, those surveyed in this study — the consensus is overwhelming, 97% or 98% to 2% or 3%, and the deniers are less accomplished in their field by the standard objective measurement of scientific accomplishment, publication history.
Or maybe, instead of lumping people into camps, it would be useful to discuss only points of supposed scientific uncertainty without reference to group affiliation of any kind, especially political, and just let each participant state our own understanding of each issue.
Note that the peer reviewed study I just cited does not lump people into arbitrarily defined, subjective or ill-defined camps, it divides them along scientifically defined terms according to their stated understanding of a well-defined physical phenomenon. That is a legitimate distinction that Anderegg, et al made.
As long as even one side persists in misdirected argumentation, no productive discussion can take place.
And I note that egregious ignorance of climate science, motivated cognition and outright dishonesty are more plausible explanations for disputing the best 98% of experts in this or any scientific field. (Those three factors of course apply in different proportions to different climate science deniers, but at least one of them applies to every climate science denier.)
My hypothesis regarding the roots of climate science denial also wins on the principle of parsimony, by the way.
Since it was experimentally shown before 1910 that the atmosphere and a greenhouse achieve their effects in physically, and mechanically distinct fashions, the word “greenhouse” should have vanished from the climatological lexicon long ago.
Presumably you’re talking about Wood’s February 1909 paper in Phil. Mag., which claimed to prove no greenhouse effect in either greenhouses or the atmosphere. This was just a short page and a half, and contained no numerical information whatsoever besides what he reported as the common temperature of the two boxes, along with a previous reading he decided couldn’t be right which he dealt with by placing a glass window over the salt window (hopefully with some ventilation). Wood used this result as evidence against the possibility of warming of the Earth by IR-trapping gases in the atmosphere.
The conclusions of Wood’s little note were challenged in the July issue by none other than the Director of the Smithsonian Astronomical Observatory, Charles Greely Abbot, later Secretary of the Smithsonian from 1930 to 1945, who pointed out that three glass covers on a box had been demonstrated at the Observatory ten years earlier to raise the internal temperature of the box to 118 °C. Unlike Wood, Abbot did a number of calculations of the expected effect, taking into account the typical atmospheric conditions above the location of Wood’s experiment (Baltimore MD), and expressed puzzlement as to Wood’s results.
People then forgot about Wood’s experiment until it was noticed in the latter part of the century and given a new lease on life by those arguing that greenhouses warm only by trapping air and not radiation. What they neglected to notice was Abbot’s challenge a few months later. Instead Wood’s experiment went viral, reborn in the public’s mind as a thoroughly researched icon of experimental physics in the service of climate science, when in fact it was nothing of the kind.
No one familiar with experimental methods in physics could possibly take this experiment seriously. It is riddled with methodological errors. One glaring one is that Wood neglected to take into account that his extra glass covering the salt window will itself trap radiation and heat up even when ventilated. He also made no attempt to investigate possible sources of errors, or to document the experiment in any reasonable detail. No dimensions or any other numerical parameters of the experiment were given and we have no idea whether the boxes were 2 inches or 2 feet on a side (presumably closer to the former since large IR-transparent windows are a rarity in optical labs), or whether they were cubes or flat trays, or how thick the windows were other than that they were the same thickness, etc. etc.
This makes it impossible to repeat Wood’s experiment using the same dimensions. It cannot be considered a serious physics experiment, and Wood explicitly disclaimed it as such in the paper.
I’ve tried tried duplicating the experiment myself with the same combination of glass and optical quality salt windows as Wood, using 6 mm thick windows for both and the largest optical quality salt window I could find at optical supply houses, 2″ x 2″. The temperatures within each box vary by more than 20 °C, increasing towards the bottom, and it is easy to get any result one wants by suitable positioning of the thermometers. Wood was presumably unaware of this variation since he speaks only of “the temperature inside the box”, which is like talking about the temperature of a fridge without specifying whether you mean the freezer portion or somewhere else.
I found that the corresponding points in the two boxes differed by 2-4 degrees, with the glass box being hotter (in accordance with the theoretical calculations). I’m still in the process of calibrating the apparatus more carefully (it currently has three TMP05B digital thermometers per box, which I may increase — I just bought another 25 from Digikey last month, they’re only $2.50 each at that quantity), and collecting more measurements (I sample all 6 thermometers every 5 seconds, giving a lot of data to work with during warm up, cool down, etc.). I’ll be writing all this up in due course, this year has been rather hectic with a number of other projects taking precedence.
Incidentally this question “how do greenhouses work” is discussed in a chapter of a book by Craig Bohren. You can read the relevant section here, or just google for “delicate shade of purple while sputtering” (in quotes). Bohren describes a controversy that erupted in 1974 over this question, discussed in the Journal of Applied Meteorology and Optical Spectra and running for a couple of years. At the end Bohren concludes with the point that greenhouses that don’t show the effects of IR trapping tend to be “set in windy environments and have thin walls.”
I am disappointed that a scientist like Judy would repeat what smacks of junk science without even raising an eyebrow, and worse yet, proposing that a perfectly sound name be changed to “Tyndall effect” without bothering to check whether there is any substantive justification for this urban legend that originated with Wood’s parody of a physics experiment.
Vaughan,
Nasif Nahle repeated Woods experiment and plans some more variations. You may be interested in reading his results and contacting him if you haven’t heard of it already:
http://www.biocab.org/Wood_Experiment_Repeated.html
Kuhnkat^2, I pointed out some weeks ago to Nahle (via an intermediary since this was on Facebook) that the 3 micron polyethylene he said he was using as a proxy for a salt window would have problems with reinforcing reflections because it was so incredibly thin as to be a quarter-wavelength at those wavelengths. (Actually I was amazed he could get polyethylene bags that thin.) Nahle responded by restating the thickness as 0.3 mm — apparently he’d misread the datasheet.
I am mystified that any serious experimental scientist could be off by a factor of 100 in estimating thickness of anything. That’s like looking at a 100 meter sprint track and estimating it at 1 meter.
I then pointed out that 0.3 mm would not work as a salt window proxy because it was so thick its absorption would be close to that of glass. This would explain why Nahle was unable to see any difference between polyethylene and glass. If there’s a difference, one isn’t going to see it with 0.3 mm thick polyethylene.
Vaughan,
Thank you for the information.
To make a repetition of the Wood’s experiment have any significance, it must be done in a way, where physics predicts an observable effect. It’s of no significance to do it so that everybody predicts the same outcome.
That means in practice that the temperature of the glazing must differ significantly from the temperature of the surface being covered, because with the same temperature the radiation absorbed and emitted by the window will not change the energy loss from the greenhouse. If the internal convection is by far the strongest energy transfer mechanism, then the temperatures will be essentially equal, and no effect is expected based on any theory I have heard about. That’s typical for standard greenhouse. Therefore the results of Wood may well agree with basic physics knowledge and repeating the experiment may give non-conclusive results.
ss,
You are confusing your mania with passion and very few people would think that what you present here represents an example of reason.
You are losing what little reason or passion you had because you are frustrated that a group of skeptics dares to openly point out the problems in your faith. Problems which, from your extreme anger and defensivness when they are discussed, you probably know at some level are not without merit.
The need of the AGW faithful approach skeptics as dishonest schills part of a cynical conspiracy is not simply childish on your part, it is not supported by facts.
You admit you are an amateur in this, so your opinion on this is no stronger than the opinion of any other lay person involved in this.
And the history of science teaches us that what you do rely on- consensus and authoritative claims, is not actually an effective way to determine the truth.
So I would suggest that you would far more successful if you would wipe off the spittle you have sprayed out in your anger and consider that the skeptics also care about the Earth, the future, our children and grandchildren, and truth.
Dehumanizing your opponents really only exposes weaknesses in yourself.
@Vaughan Pratt… I used the proper polyethylene, as it is specified in the article on the results, and followed the correct scientific methodology.
You used a similar polyethylene film and you didn’t report any problems with the reflectivity of your polyethylene film used in your “experiment”, which lacked of proper control.
I didn’t limit my experiment to a solitary class of polyethylene, but I used two kinds of LDPE film.
My results are not biased and the peer reviewers of the article have photographs of each phase of the experiment, including photographs of thermometers taken each five minutes.
Sorry, but my experiment is absolutely correct and yours is biased.
Sorry, but my experiment is absolutely correct
Very compelling. You should trademark the “experiment is absolutely correct” phrase, like Safeway’s trademarked “Eating right” label on their sugarless icecream.
and yours is biased.
Very insightful of you. I freely admit a bias towards anything that improves our understanding of atmospheric physics. Good catch there, obviously we need to be more respectful of those that don’t tolerate that kind of understanding.
Your complete lack of bias presumably has to do with making sure that no one believes this cockamamie AGW theory. In that sense you could not possible be any less biased. Good on yer, mate, for your total lack of bias in this difficult area.
My interest is solely in the science, not in the biases of those discussing it. If you’re only interested in those biases then we can agree to agree.
For there to be *no* back radiation, which is his claim,
Just for the record, what I’m claiming is not that there is no back radiation but that the only sense in which back radiation warms the Earth is the same sense in which a block of ice next to you warms you. That point of view may work for some people, but there may be people for whom it doesn’t work because they regard the ice as cooling you.
Committed climate skeptics may not care either way, but those trying to make sense of the subject without just taking it all on faith may have a hard time with the idea of ice as a warming agent. Why push that point of view on them when it isn’t necessary?
Because those are the facts, and by the way you never took them on faith, did you?
@settledscience you have a point here and I’m just as surprised as you appear to be that my fellow skeptics fail to see what is to me absolutely obvious.
Mr. Pratt knowingly or not gives misleading and counter-intuitive example with the block of ice which people intuitively regard as “cold” . To make a fair comparison you’d need to place yourself in the vacuum in the open space (same as the Earth) and then the block of ice next to you would indeed warm you. Just ask yourself whether you last longer in -1°C or -269°C (4 K) … it’s quite obvious you would prefer the block of ice over near absolute zero.
Why is this so hard to understand? I’m seriously shocked that this issue gets so much attention … Mr. Pratt measured infrared back-radiation himself, surely he must realize that this radiation has to warm the Earth in comparison with no radiation (no atmosphere, no back-radiation) and it would be cooler if it were absent – of how much may be in dispute but the fact that it would be cooler is undeniable, at least I thought so – it’s just so incredibly obvious!
You also made perfectly valid argument similar to mine above pointing out that he would measure -273°C if there was no back-radiation, so the mere fact that he measured more actually proves back-radiation. And that gets called “leftist culture” for displaying dismay at the fact that people do not get this basic and simple point? It really doesn’t reflect well on a broader skeptic community if some skeptics are acting like this and what’s worse, it doesn’t seem to get challenged from the more reasonable folks … that raises the question, where are they?
Is calling people leftists for challenging your position while not addressing the actual argument presented acceptable?
Nick, let me repeat your argument back to you just to make sure I understood it.
You seem to be saying that if there are two objects nearby, both cooler than you and one warmer than the other, then you are being cooled by one of them and warmed by the other.
Did I understand you correctly?
Dr. Pratt,
Everything is warming everything, just not very much.
IOW, the practical warming from a block of ice next to, say a warm body in an open place with convective protection is going to be a minor bit of trivia.
And everything is at the same time cooling.
Nick,
” To make a fair comparison you’d need to place yourself in the vacuum in the open space (same as the Earth) and then the block of ice next to you would indeed warm you.”
The warmists basic problem is unable to realise that ice warmer than 0K has reduced the body radiation towards the space which is absolute zero. Ice does not heat up the body, it reduced the heat loss by radiation to space having it in between the body and the space. It acts as a buffer similar to the atmosphere between the space and the Earth surface. Here Stefan-Boltzmann radiation law applys.
Just ask yourself whether you last longer in -1°C or -269°C (4 K) … it’s quite obvious you would prefer the block of ice over near absolute zero.”
All warm objects (above absolute zero) radiate. Assume the block of substance surrounding the earth is at absolute zero then the earth receives no radiation from this source (it actually has a temperature of course so does radiate). Pointing your (by now useless ) IR thermometer away from the earth (and at NO other body) you will read absolute zero.
As you enter the atmosphere molecules warmed by incoming and out going radiation will radiate in all directions including downwards. Pointing your thermometer “upwards” measures the downwards portion of this radiation – at the earths surface (0 metres/2 metres altitude?) this was negative 20C as you discovered. ie. 250C hotter than space. The air is acting as a warm body radiating at a temperature of -20C (remember all bodies aboveabsolute zero radiate – so the earth receives solar input but no input from space and radiates as a black body at the temperature of the top of atmosphere (where ever this is). At grond level the ground radiates at 20C has solar input and radiation from your “measured” -20C Obviously the ground is warmer than it would be if the -20C radiation were not present.
QED you have proved downward radiation! and you have shown tha
Vaughan: I think that you have expressed the dilemma very well, but you may be reluctant to follow the consequences of your ideas to their logical end. Can a block ice “warm” a person or can a cold atmosphere “warm” the much-warmer surface of the earth? The “establishment” view recognizes that both a person and the surface of the earth are constantly losing energy to and gaining energy from the surroundings by radiation. In the establishment view, “warming” means increasing the rate at which a person or the surface of the earth gains energy from the surroundings. You probably don’t feel comfortable calling this process “warming” when the radiation comes from a colder location, but the term is perfectly sensible. Anything that contributes radiant energy to a person or the surface of the earth warms it.
A block of ice can warm a person by increasing the amount of radiation a person receives from their environment. Go to Antarctica where the air temperature is -50 degC on an absolutely calm day. Build an igloo and wait until your body heat warms the inside air and inside surface of the igloo to 0 degC. Those blocks of ice with a surface temperature of 0 degC will emit more infrared radiation in your direction than the air at -50 degC did before you built the igloo.
For our planet, the “outside” air is space, which is filled with blackbody radiation at 2.7 degK. Our atmosphere, which is 200-300 degK, obviously radiates much more energy towards the surface of the earth than it would receive from space alone and therefore warms the surface.
In the case of radiation, the NET flow of energy is always from hot to cold, but there will always be some photons flowing from cold to hot. Those photons make the hotter object warmer than it would have been if the cold object had not been present. (If the cold object is removed, what is present? Empty space at 2.7 degK!)
Gee Frank ya think conduction and convection have anything to do with your igloo example???
Vaughan Pratt, 8/14/11, 1:38 am, Vaughan Pratt
Your analogy sitting next to a block of ice is brilliant.
Of course back radiation exists, but it is not heat, and consequently cannot warm Earth. But the block of ice just below 0ºC will nicely warm a block of dry ice, our beloved CO2, just below -60ºC.
Of course CO2 has a positive greenhouse effect to prevent the surface from cooling. It’s just not measurable, that’s all.
By committed climate skeptics are you distinguishing between AGW believers, like those who post here, who ought to be committed?
@Vaughan Pratt… As I said in that facebook discussion, it was not me who “calculated” the thickness of the LDPE, but a wrong information from the retailer. It was not my mistake. I called to the manufacturers, MAPASA, and they made me know the real thickness of the LDPE I used in my experiment.
I used two kinds of LDPE, 0.3 mm and 0.051 mm thick. I reported the results from 0.3 mm LDPE, but it seems you don’t know there is not any problem with thickness because the records of temperature were the same using 0.3 mm thick and 0.051 mm thick.
Sorry, try again… :D
By the way, I didn’t place my boxes directly on the floor; I constructed wood structures to hold them away from the floor.
Additionaly I wrote a guide to the experiment for any scientist or high school student can reproduce my experiment.
http://www.biocab.org/Booklet_Experiment_on_Greenhouse_Effect.pdf
:D
settledscience
“The whole article is ridiculously unphysical. The *temperature* of the atmosphere at 2000m, as measured by radiation *from* the atmosphere above him, does not suck up more upward infrared, aka outgoing longwave radiation!”
On the other hand, Temperature difference is the cause of convective Heat flow from the surface to the colder atmosphere. It seems that Net Energy flows from a higher energy potential to a lower one. (See electrical circuits, fluid mechanics, thermodynamics, etc.) Perhaps, one day, that too may also be known as settled science. :)
P.S. Observations of atmospheric circulation confirm the Heat flow pattern of rising at low latitudes and descending at higher latitudes (where atmosphere is warmer than surface).
You had best apologize Vaughan Pratt on this one.
Like hell I should apologize, you disingenuous ignoramus. Conduction and convection in fact do not suck up more infrared radiation, and his argument is in fact unphysical where it takes low temperature to mean zero back radiation. In fact, for all temperatures above 0K, there is some thermal radiation. That is what I actually said.
The point of his article was to try to make the least scientifically illiterate argument against back radiation. Misrepresent what I said all you want. The truth is that nothing I said contradicts any facts of heat transfer.
You had best apologize to me on this one.
Dear Luis,
Nicely explained!
Work is required to transfer heat from a cold reservoir to a hot reservoir. Where is this work in the mathematics of the greenhouse gas theory?
In terms of radiative energy space could describe a “block of a substance at -270C”. And in regards to space and bodies in them energy can’t be transfer via conduction or convection.
And in space a block of ice could be warmer than space, but isn’t warmer than a living body [which would need to be in a spacesuit to be living- a dead human not in spacesuit would remain warmer longer if near a block of ice in space. Or if spacesuit is designed so that in space an person is cold, being near the block ice would make that person warmer- very slightly.]
I gather from the comments that the above article is suppose to be wrong- but is suppose to serve the purpose of something to slay.
With the goal of causing dragons to become extinct apparently- how uneco friendly.
I would say the cold sky doesn’t cause pavement to increase in temperature, but certainly causes the air to be warmer. Humans are more interested in air temperature in a white box 5 feet off the ground than the ground [surface] temperature.
If you measure the watt per square meter from the Sun, at noon on a clear day with sun directly over head at sea level on earth it will be about 1000 watts per square meter. Without there being an atmosphere, in same time and location instead of 1000 watt, one would have about 1300 watt per square meter. Therefore one would have more energy heating the pavement [dirt/sand/whatever]. And a cold sky isn’t going cause any significant heating of the pavement [certainly not 300 watts worth].
The 300 watts is lost somewhere, and seems on clear day much of it must be “lost” warming the atmosphere.
Luis,
Charlie is correct. From the point of view of radiation, that is exactly what a vacuum is. What confuses everyone is that you have to have the correct comparison case. An earth without IR-absorbing substances (greenhouse gases and clouds) is an earth where all the radiation it emits escapes to space. An earth with IR-absorbing substances is one where some of that radiation heats the atmosphere, which emits radiation some of which returns to earth. The heat flow (i.e., net flow of energy) is still from the warmer earth to the colder atmosphere but that flow is less for a given surface temperature than it would be if the atmosphere were transparent to IR radiation.
And, by the way, even if you don’t believe back-radiation exists (despite the wealth of experimental information that it does), as long as you believe the Planck Equation (i.e., that the heat [i.e., net energy] flow from a warmer object to its cooler surroundings depends on the temperature of its surroundings as well as the temperature of the object), you have to believe in the greenhouse effect.
The radiation model is much too simplistic. Why is the surface temperature of Venus the same on the dark and light side, even though night on Venus is 120+ earth days?
What the atmosphere does is moderate the surface temperature. It makes days cooler and nights warmer. The more atmosphere (Venus) the atmosphere, the greater the effect, until the dark and light sides are the same temperature. This effect can easily be observed on earth whenever it is cloudy as compared to clear.
The problem with simplistic radiation models is that radiation is a 4th power function and the average of the 4th power is not equal to the 4th power of the average. Physics tells us that radiation is the average of the 4th power, while climate science would have us believe that radiation is the 4th power of the average. So long as climate science works with average global temperature to calculate a radiation budget it is unphysical nonsense.
Climate science does not work with global average temperature to calculate a radiation budget. Climate models calculate radiative transfer and fluxes in grid cells all over the globe in response to the temperature and humidity profile, cloud characteristics, and gaseous and aerosol composition at the grid cell at that particular point in time (multiple calculations are made in each grid cell for each day in the model integration.) Setting up a straw man (like climate scientists do back of the envelope calculations and base their entire argument on such simple things) and then knocking it down is pointless, not to mention confusing and misleading.
If you want to understand why we have confidence in calculations of radiative transfer by sophisticated radiative transfer codes use in most climate models, see this previous thread
http://judithcurry.com/2010/12/05/confidence-in-radiative-transfer-models/
“cloud characteristics, and gaseous and aerosol composition at the grid cell at that particular point in time”
Is this a grid cell on the surface or 3D cells above the surface? Do these models take into account the Energy Pressures (aka Temperature) and Enthalpy of the layers of atmosphere and surface?
Both temp and Enthalpy decline with altitude showing that it takes less time to heat and cool those regions. If you model a cooler region with lower enthalpy “warming” a region that is higher in Energy Pressure (Temp) and Enthalpy (Oceans as Air are an extreme example), you will find the cooler less dense region does even a poor job at slowing the cooling rate of the Warmer region.
Now one might postulate that there is enough cooler atmosphere to slow the cooling below, but we also need to take into account the elasticity of the atmosphere. Since the atmosphere expands as it gets warmer, temperature is converted into work to increase the volume against gravity. The Energy is not lost, it is simply represented by the increase in volume. As altitude increases the amount of work needed to expand decreases. The Variable Height of the Tropopause is a good reference for this phenomena.
So what we find is that an atmosphere that significantly slows the surface cooling will simply increase the rate at which the atmosphere expands, and in doing so creates a bigger volume to store the “trapped” energy. Smash the Tropopause at the equator down to polar altitudes and you will experience a TRUE GreenHouse Effect.
What I don’t believe the GH Dragons take into account is how elastic our atmosphere is. Nor do I think they are considering the declining Enthalpy as altitude increases.
The radiation model is much too simplistic. Why is the surface temperature of Venus the same on the dark and light side, even though night on Venus is 120+ earth days?
First a not-so-small correction: that’s a sidereal night, the solar night is only about 58 Earth days. (And weirder still, the Sun rises in the west and sets in the east.)
That said, this is a nice question, and one that Marov and Grinspoon make a point of addressing early on in Chapter 7 (IIRC) of their comprehensive treatment “The Planet Venus”. The simple answer depends primarily on two factors.
(i) At night the top of the SO2 cloud rises from its daytime altitude of 65 km to some 90 km (they don’t say why IIRC) where it is extremely cold, around 170-200 K, whence relatively little radiation to space happens, considerably less than takes place from the night surface of Earth which has enough wide open atmospheric windows for significant radiative cooling of its ~280 K surface. Assuming 200 K is correct (I’m down in Pacific Grove today, where my MT250 shows the clear but humid 7 pm sky at -6 C incidentally, and won’t have access to my copy of M&G until tomorrow afternoon), this would cool Venus at 90 W/m2, whereas 280 K on Earth radiates at 350 W/m2. At 170 K it’s down to 47 W/m2 though I suspect the night radiation doesn’t get this low.
(ii) Whereas it is the Earth’s surface that is cooled by radiation to space, it is only the SO2 clouds in a range below 90 km that are cooled by this 90 W/m2. The clouds down to 45 km or so damp out any remaining diurnal variation so that the subcloud atmosphere is oblivious to it except for perhaps 25 W/m2 of visible sunlight throughout the subcloud and surface switching off abruptly at night, not a big difference.
A third factor is that the 734 K surface of Venus is exchanging heat with the atmosphere immediately above at a flux density of 15 KW/m2 (the surface emissivity is 0.9 or it would be 16.5 KW/m2). This so dwarfs these small diurnal fluctuations that it is impossible to have any significant temperature variation at the surface in the course of a Venusian night, even if those fluctuations could penetrate the clouds. But they don’t, except for the miniscule visible 25 W/m2 switching off, so this third factor doesn’t even come into play. When all hell breaks loose, turning off the lights doesn’t turn off the heat.
Vaughan,
this is the REAL Greenhouse you are describing, per Real Climate and the IPCC, that the average radiative altitude rises to where the components are too cold to radiate the same amount of energy. My counter argument is that the rising atmosphere is an expansion that decreases the density of the particles allowing the radiation through to space from a warmer level that wasn’t making it before. I have, so far, not seen this particular concept addressed, although it may have been. Any idea?? Would the models correctly deal with this?
The diagram I saw of the Venusian atmosphere is more of a compression of the day side. That is, it would appear that it has been pushed down possibly by the solar wind. Being much closer to the sun there would be a much stronger effect by the solar wind. Having a much longer day allows for more of a distortion also. This is just a guess but seems to fit the shape.
One other cool thing I ran across, the Russian pictures were taken with AMBIENT LIGHT!!! They are apparently near IR pictures!!!!!!
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My counter argument is that the rising atmosphere is an expansion that decreases the density of the particles allowing the radiation through to space from a warmer level that wasn’t making it before.
Not quite sure what you’re referring to here, but if you mean the lapse rate on Venus, it is very close to that of Earth, with the formula g/c_p for lapse rate requiring only small adjustments to gravity g and constant-pressure specific heat c_p. Theory and observation are in excellent agreement for Venusian lapse rate, just as for Earth.
One other cool thing I ran across, the Russian pictures were taken with AMBIENT LIGHT!!! They are apparently near IR pictures!!!!!!
Did they say they were using IR? During the day the surface is illuminated with some 15 W/m2 of sunlight, which is plenty of ordinary visible light for even a commercial off-the-shelf video camera. According to Marov and Grinspoon the sunlight has a distinctly orange hue.
I am referring to the issue of more CO2 alledgedly raising the average emission altitude so that it becomes colder and cannot emit as much energy bottle necking emissions until the atmosphere heats to the ground as explained by RC and IPCC. This is the real Greenhouse effect that was supposed to give the large C increases.
http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/
What I am saying is that as the GHG’s increase, the atmosphere from ground level on up will warm marginally due to the extra GHG’s transferring more energy to the atmosphere causing a small expansion of the atmosphere. The density of the GHG’s or particulate that could bslow or block the radiation directly to space is lowered as the atmosphere is warmed and expands. 200ppm of CO2 will not significantly increase the density of the atmosphere as it is “well mixed.” The extra space between IR blockers or absorbers should allow emissions from absorbers that are almost as warm as before the addition. I THINK, I don’t KNOW, that this should offset the amount of GHG’s that are added to colder altitudes reducing their temperature and effectiveness.
The IPCC claimed the Hotspot would result from this bottleneck, yet, we never seem to see it reach measureable size for any period of time. I don’t think they made it up so the alternative is that they missed something and this would seem to be a possibility. The actual numbers are pretty small so it would also seem possible that there is an unintentional error in these computations that create the bottleneck and it could be in any of the parameters or more than one or be in the algorithym created to make it possible to make the computations in the model
Either that or the humidity is dropping!!.
Venus or any atmosphere with GHG’s should be similar. On a diurnal basis this would be a small change in the radiation rate as the atmosphere heats and expands. On Venus, the compression of the atmosphere on the dayside would be the opposite pushing the GHG’s closer together and slowing a little more IR.
Of course this is probably built into the models correctly and I’ve got nuttin.
Yes, the consensus IS that there is actual insolation at ground level on Venus. The light was quite red though so, along with other issues, it has made some think that this may be a mistake and it is the glowing lava providing near infrared for the viewing.
You may have heard of John Ackerman, a retired Physicist who has written some books considered pseudo-scientific by many. Of course, they label anything pseudo that doesn’t fit their belief, so I don’t really know. I found his descriptions of a possible Sulfur cycle on Venus quite compelling. Unfortunately I don’t have the knowledge to evaluate it. I think he is also disliked because he thinks Velikovsky got some things right!! Orange?? Definite difference from the red Ackerman stated. Orange would probably fit the temperature better. Did they suggest what caused the orange?
http://www.firmament-chaos.com/papers/fvenuspaper.pdf
I am referring to the issue of more CO2 alledgedly raising the average emission altitude so that it becomes colder and cannot emit as much energy bottle necking emissions until the atmosphere heats to the ground as explained by RC and IPCC. This is the real Greenhouse effect that was supposed to give the large C increases.
Let me start by responding to this much, which may have the side effect of also addressing some of the other parts of your comment.
The way I think of Venus’s atmosphere is as a gaseous ocean of CO2 molecules and photons. Photons are bosons and hence pass through each other like ghosts. They also have ill-defined identities, unlike fermions, and one should think of them as short-lived, surviving no longer than between their emission and subsequent absorption. Absorption can be viewed as colliding with a CO2 molecule whose cross-section depends strongly on the energy (aka wavelength) of the photon: the molecule looks “larger” when the photon is nearer some resonance of the bonds of the molecule.
My justification for this viewpoint is that photons leave Venus’s atmosphere quite analogously to the way water molecules leave Earth’s ocean, namely by slow evaporation from the surface. (Hawking has pointed out that even black holes can evaporate slowly, albeit via quantum tunneling rather than the straightforward radiative evaporation from Venus’s atmosphere.) Most of the photons remain trapped in the atmosphere
Insolation can be understood as much higher-energy solar photons that can only collide with clouds and the surface. Clouds both absorb and scatter solar photons, and a few of the scattered ones, particularly the orange ones which are least likely to be absorbed by sulfur atoms, avoid capture by the clouds and make their way into the subcloud where they can viewed as ordinary wave-nature radiation beaming down to the surface with negligible interaction with the relatively clean CO2 of the subcloud. They constitute sunlight at the surface of Venus, which down-converts them to slow-frequency (longer-wavelenght) photons that replenish the photon component of the atmosphere. This replenishing together with the corresponding conversion taking place in the clouds is sufficient to offset the very slow evaporation at the top in order to maintain a stable (and huge) photon population in Venus’s atmosphere ocean over millions of years.
Photons dart about of course, but so do CO2 molecules. What photons and molecules have in common is that the bulk of them remain trapped in the ocean.
One can think of both photons and molecules as being compressed by the huge amount of ocean above them, more at the bottom than the top. Pressure is expressed as kinetic energy. KE in molecules is speed squared, in photons it is frequency. KE in molecules is linear in pressure, in photons it is linear in depth with coefficient g/c_p, called lapse rate. (Hence KE of molecules is not linear in that of photons because pressure is not linear in depth.)
Does this way of thinking about Venus’s atmosphere, along with the two principles in the preceding paragraph that quantify the qualitative picture, address any of your questions?
depends strongly on the energy (aka wavelength)
Sorry, replace “wavelength” by “frequency”.
@Vaughan Pratt…
VP: “Photons are bosons and hence pass through each other like ghosts.”
You’re forgetting photons have inertial mass. Your second assertion is not a scientific argument even if you believe in ghosts.
VP: “Absorption can be viewed as colliding with a CO2 molecule whose cross-section depends strongly on the energy (aka wavelength) of the photon: the molecule looks “larger” when the photon is nearer some resonance of the bonds of the molecule.”
The cross-section of a carbon dioxide molecule doesn’t depend “strongly” of the energy of the photon, but of the internal energy of the molecule.
The cross section of a molecule of carbon dioxide is well defined and it is 5 x 10^-22 cm^2.
VP: “My justification for this viewpoint is that photons leave Venus’s atmosphere quite analogously to the way water molecules leave Earth’s ocean, namely by slow evaporation from the surface. (Hawking has pointed out that even black holes can evaporate slowly, albeit via quantum tunneling rather than the straightforward radiative evaporation from Venus’s atmosphere.) Most of the photons remain trapped in the atmosphere.”
So carbon dioxide on the Venus works as a coolant of the surface, not as a warmer. All scientific literature on evaporation clearly states that evaporation is a coolant process. If you say that carbon dioxide on Venus surface, like water molecules on Earth, then you’re on my side, i.e. carbon dioxide is a coolant, not a warmer.
On your final assertion, a molecule that “retains” the absorbed thermal energy by only 120 picoseconds cannot “trap” photons. Your argument is unphysical.
VP: “Insolation can be understood as much higher-energy solar photons that can only collide with clouds and the surface.”
I don’t know where you take this argument from, but it is twisted physics. Insolation is the load of incident solar power on Earth’s surface. It can be applied to any other celestial body (not ghosts, okay?).
Insolation is mitigated by the atmosphere before solar radiation hits on the surface. Sorry, but this series of confusions and twisted concepts are the roots of AGW pseudoscience.
VP: “Photons dart about of course, but so do CO2 molecules. What photons and molecules have in common is that the bulk of them remain trapped in the ocean.”
Neither carbon dioxide neither we can “trap” photons. Remember uncertainty principle. It is the energy carried on by photons what is momentarily retained as long as an electron leaves a high energy microstate down to its fundamental stationary microstate.
VP: “One can think of both photons and molecules as being compressed by the huge amount of ocean above them, more at the bottom than the top.”
Sorry, Vaughan but your argument above is nonsense. Could photons be compressed? Yes or not?
No, we cannot think of both photons and molecules as being compressed by mechanical compression as you suggest. We could compress virtual pulses by means of virtual data, not quantum/waves.
Photons are not compressed by the density of the medium. Gravity has an influence on both wavelength and frequency of a photon, but you cannot say the photon is compressed as if it were a gas. Imagine a piston filled with compressed photons.
It seems you believe that photons can be compressed by hydraulic pressure.
VP: “Photons are bosons and hence pass through each other like ghosts.”
You’re forgetting photons have inertial mass. Your second assertion is not a scientific argument even if you believe in ghosts.
VP: “Absorption can be viewed as colliding with a CO2 molecule whose cross-section depends strongly on the energy (aka wavelength) of the photon: the molecule looks “larger” when the photon is nearer some resonance of the bonds of the molecule.”
The cross-section of a carbon dioxide molecule doesn’t depend “strongly” of the energy of the photon, but of the internal energy of the molecule.
The cross section of a molecule of carbon dioxide is well defined and it is 5 x 10^-22 cm^2.
VP: “My justification for this viewpoint is that photons leave Venus’s atmosphere quite analogously to the way water molecules leave Earth’s ocean, namely by slow evaporation from the surface. (Hawking has pointed out that even black holes can evaporate slowly, albeit via quantum tunneling rather than the straightforward radiative evaporation from Venus’s atmosphere.) Most of the photons remain trapped in the atmosphere.”
So carbon dioxide on the Venus works as a coolant of the surface, not as a warmer. All scientific literature on evaporation clearly states that evaporation is a coolant process. If you say that carbon dioxide on Venus surface, like water molecules on Earth, then you’re on my side, i.e. carbon dioxide is a coolant, not a warmer.
On your final assertion, a molecule that “retains” the absorbed thermal energy by only 120 picoseconds cannot “trap” photons. Your argument is unphysical.
VP: “Insolation can be understood as much higher-energy solar photons that can only collide with clouds and the surface.”
I don’t know where you take this argument from, but it is twisted physics. Insolation is the load of incident solar power on Earth’s surface. It can be applied to any other celestial body (not ghosts, okay?).
Insolation is mitigated by the atmosphere before solar radiation hits on the surface. Sorry, but this series of confusions and twisted concepts are the roots of AGW pseudoscience.
VP: “Photons dart about of course, but so do CO2 molecules. What photons and molecules have in common is that the bulk of them remain trapped in the ocean.”
Neither carbon dioxide neither we can “trap” photons. Remember uncertainty principle. It is the energy carried on by photons what is momentarily retained as long as an electron leaves a high energy microstate down to its fundamental stationary microstate.
VP: “One can think of both photons and molecules as being compressed by the huge amount of ocean above them, more at the bottom than the top.”
Sorry, Vaughan but your argument above is nonsense. Could photons be compressed? Yes or not?
No, we cannot think of both photons and molecules as being compressed by mechanical compression as you suggest. We could compress virtual pulses by means of virtual data, not quantum/waves.
Photons are not compressed by the density of the medium. Gravity has an influence on both wavelength and frequency of a photon, but you cannot say the photon is compressed as if it were a gas. Imagine a piston filled with compressed photons.
It seems you believe that photons can be compressed by hydraulic pressure.
VP: “Photons are bosons and hence pass through each other like ghosts.”
You’re forgetting photons have inertial mass. Your second assertion is not a scientific argument even if you believe in ghosts.
VP: “Absorption can be viewed as colliding with a CO2 molecule whose cross-section depends strongly on the energy (aka wavelength) of the photon: the molecule looks “larger” when the photon is nearer some resonance of the bonds of the molecule.”
The cross-section of a carbon dioxide molecule doesn’t depend “strongly” of the energy of the photon, but of the internal energy of the molecule.
The cross section of a molecule of carbon dioxide is well defined and it is 5 x 10^-22 cm^2.
VP: “My justification for this viewpoint is that photons leave Venus’s atmosphere quite analogously to the way water molecules leave Earth’s ocean, namely by slow evaporation from the surface. (Hawking has pointed out that even black holes can evaporate slowly, albeit via quantum tunneling rather than the straightforward radiative evaporation from Venus’s atmosphere.) Most of the photons remain trapped in the atmosphere.”
So carbon dioxide on the Venus works as a coolant of the surface, not as a warmer. All scientific literature on evaporation clearly states that evaporation is a coolant process. If you say that carbon dioxide on Venus surface, like water molecules on Earth, then you’re on my side, i.e. carbon dioxide is a coolant, not a warmer.
On your final assertion, a molecule that “retains” the absorbed thermal energy by only 120 picoseconds cannot “trap” photons. Your argument is unphysical.
VP: “Insolation can be understood as much higher-energy solar photons that can only collide with clouds and the surface.”
I don’t know where you take this argument from, but it is twisted physics. Insolation is the load of incident solar power on Earth’s surface. It can be applied to any other celestial body (not ghosts, okay?).
Insolation is mitigated by the atmosphere before solar radiation hits on the surface. Sorry, but this series of confusions and twisted concepts are the roots of AGW pseudoscience.
VP: “Photons dart about of course, but so do CO2 molecules. What photons and molecules have in common is that the bulk of them remain trapped in the ocean.”
Neither carbon dioxide neither we can “trap” photons. Remember uncertainty principle. It is the energy carried on by photons what is momentarily retained as long as an electron leaves a high energy microstate down to its fundamental stationary microstate.
VP: “One can think of both photons and molecules as being compressed by the huge amount of ocean above them, more at the bottom than the top.”
Sorry, Vaughan but your argument above is nonsense. Could photons be compressed? Yes or not?
No, we cannot think of both photons and molecules as being compressed by mechanical compression as you suggest. We could compress virtual pulses by means of virtual data, not quantum/waves.
Photons are not compressed by the density of the medium. Gravity has an influence on both wavelength and frequency of a photon, but you cannot say the photon is compressed as if it were a gas. Imagine a piston filled with compressed photons.
It seems you believe that photons can be compressed by hydraulic pressure.
Thank you for sharing your interesting understanding of physics with us, Nasif. Would you have any objection to its use as an illustration of the depth of that understanding by climate skeptics?
“An earth without IR-absorbing substances (greenhouse gases and clouds) is an earth where all the radiation it emits escapes to space. An earth with IR-absorbing substances is one where some of that radiation heats the atmosphere, which emits radiation some of which returns to earth. The heat flow (i.e., net flow of energy) is still from the warmer earth to the colder atmosphere but that flow is less for a given surface temperature than it would be if the atmosphere were transparent to IR radiation.”
Ok, so we will ignore the much higher heat transfer of a warm surface conducting heat to any gas [whether greenhouse or not] and the convection of this gas [warm air rises] heating the cooler air [and lifting such things as gliders in thermals]. And just talk of heat transfer via radiant energy:
First, of course, something has to get hot to radiate much energy- water 70% of the surface planet doesn’t get a hot as sand or rocks. So tropical oceans may be say 80 F and sand might be +160 F. Since oceans dominate this world we might take a average surface temperature of say 70 F daytime [since ocean retain their heat, say 60 F average nite time].
So basically we talking about a surface temperature of 60-70 F warming an atmosphere.
Now, the blog post we replying to said: “the atmosphere is below freezing at all altitudes above 2 km, based on a lapse rate of 10 °C/km.”
I don’t know how accurate 10 °C/km is, I usually use 3 F per 1000′ [which is less than 10 °C/km]. But temperature does lower at a standard rate as one goes higher- if go up 1000′ of elevation anywhere on earth, the temperature will drop by about 3 F.
So, you are in the middle of the ocean the average temperature is 70 F and it’s nite time. You get into a balloon and go up to 1000′ above sea level.
Below you is body of air and the ocean itself which is about 70 F, the sky above you is colder, and the air temperature is 67F. If you go another 1000 feet higher it will be about 64 F. In terms of radiant heat, nothing much has changed- the sky above is cold and the air and ocean is warm.
If you seeing in infrared, it all looks the same. If measuring the radiant, nothing has changed, except the air temperature is colder. You have the same area radiating heat to warm the air which is surrounding you- and very little changes in this regard even if you you up 100 miles- other than there is very little air to warm.
Judith,
I agree with Charles, why on earth have you allowed an article like this to be pulished on your blog, when clearly the author doesn’t understand basic physics ?
Maybe to give you the opportunity to teach the author (and others)?
Nah, Its to give Tom a chance to express his indignation.
Tom: Vaughn has posted a detailed scientific argument for discussion. Saying it should not be posted and that he does not understand basic physics just makes you look stupid, as neither is a counter argument. We are here to work, not to trade insults.
Thanks David. Vaughan has written an essay that is useful in focusing the greenhouse dragon discussion.
Judith,
You should thank David here.
I wrote a comment in the previous “dragon thread”.
http://judithcurry.com/2011/08/10/greenhouse-dragon-technical-discussion-thread/#comment-97627
That presents in very rough terms a different way of looking at the same physics – and without direct reference to back radiation in any way. As I said, the physics is still the same, only the way of looking at it differs.
Judith,
I am sure I don’t need to lecture you on how the’ greenhouse effect’ works. I can support your idea of wide ranging discussion of climate change involving a wide audience but that has to be predicated by sound basic physics or we are all going to waste a lot of time.
It is true that much of the atmosphere is colder than the surface but the point about greenhouse gases is that they reduce surface cooling by reducing the outgoing long wave radiation to space which is close to absolute zero. They do this by absorbing the outgoing radiation and then emitting isotropically.
Tom, you know this and I know this. Stating that others should believe this because people like you and I know this hasn’t worked for some hard core group of skeptics (which by now are becoming increasingly marginalized, but do remain hard core, Claes Johnson being a case in point). Since this seems to be such a popular discussion topic, and I have been trying to slay this particular dragon, I am trying to focus the dialogue in order to chip away at the skydragons and the people that are persuaded by their perspective. In the process, many are learning something and people are honing their arguments and improving their methods of explanation.
Dr. Curry, Well said, I say…
“Tom, you know this and I know this. Stating that others should believe this because people like you and I know this hasn’t worked for some hard core group of skeptics (which by now are becoming increasingly marginalized, but do remain hard core, …”
almost biblical.
You have your metaphors crossed. The “skydragons” are the atmospheric warming effects of CO2 et al. You appear to be feeding and coddling them, not slaying them.
I don’t know anyone who disputes that CO2 randomizes or diffuses directional IR radiation. The question is…how much “work” can this diffused energy do? Can it increase the temperature of the emitter or is the effect already “built-in” to the emitter’s temperature?
The atmosphere expands.
The cold, rarefied atmosphere which intrinsically has small thermal mass and correspondingly small thermal storage capacity expands (and contracts).
How does this happen without the absorption of energy, a significant part of which comes from IR emitted from the surface. BTW, this happens where the atmosphere is neither cold nor rarified.
I don’t know anyone who disputes that CO2 randomizes or diffuses directional IR radiation.
While it is true that CO2 scatters IR, it also absorbs it, and it is the latter that is the relevant effect. The absorbed EM energy initially becomes vibrational energy in all vibrational modes of the absorbing molecule, and is subsequently redistributed as kinetic energy in all permitted degrees of freedom of nearby molecules as a result of collisions.
Yep, it absorbs energy and emits the absorbed energy just 120 picoseconds after it has absorbed that energy. Besides, the photon emitted by carbon dioxide has a longer wavelength and a lower frequency, so this energy cannot be absorbed by other molecules of carbon dioxide.
Tom,
the Greenhouse Effect is about the “bottleneck” of energy in the upper tropopause to stratosphere according to RealClimate and the IPCC. The NetEnergy flows have nothing to do with it. This is why the term backradiation is silly. It is used to describe one particular direction, down, of a radiative function in all possible directions. The energy is standard SB net energy flux. Trying to talk about it without its causative factor, the OLR, is silly. Without one you do not have the other.
The alledged reduction in radiative capacity due to a colder average radiation temperature from extra CO2 is what causes AGW as it backs up the energy in the troposphere. There is no exceptional increase in how much the net radiation from the surface is slowed from the extra CO2.
http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/
Concentrating on the ground level effects completely misses what the IPCC and RealClimate have been saying for years. Or have I missed a NEW AGW Theory??
Why are we still discussing ground level radiative transfer??
GHE is not about either what happens at TOA or about energy fluxes at surface, it’s about both both. And it’s influenced by the lapse rate in between. All these must be considered to get the right picture. CO2 has a significant influence both at the top and at the bottom. In particular it has a large influence on the bypass of energy from the surface to the space by IR that’s not absorbed even once on the way, but that’s not the only important mechanism.
kuhnkat: You are basically correct. It is not a new theory…It is just different levels of refinement. The simple radiative picture allows you to understand the basic qualitative effect, but ultimately it is not that useful because its focus is on what is happening in terms of radiation at the surface, whereas we know that convection plays a large role in the transport of energy from the surface.
That is why, ultimately, you have to include convection and when you do this, it turns out that the easiest way to figure out what happens to the temperature at the surface is to start at the top of the atmosphere where again you need only worry about radiation and then work your way down using the fact that the role of convection is to maintain the lapser rate in the troposphere at the adiabatic lapse rate.
Further, I regard it as a major coup for climate blogospheric dialogue for someone like Vaughan Pratt to enter the fray
http://en.wikipedia.org/wiki/Vaughan_Pratt
a person of demonstrated “meta-cognitive expertise”
Very impressive biography. And originally from Australia no less. Who would have thunk it?
I demystify Downward Longwave Radiation and backradiation
in series of posts on my blog:
http://claesjohnson.blogspot.com/search/label/myth%20of%20backradiation
http://claesjohnson.blogspot.com/search/label/DLR (short)
and show that it to belong to fiction and not physics. I thus agree with Vaughan.
I have asked Judy about her standpoint is: fiction or reality?
Since you open to debate Judy, don’t you have to say something yourself,
or do not have any opinion at all?
Back radiation is a phrase, one that I don’t use myself, and it is not a word that is used in technical radiative transfer studies. The argument is made technically from the spectral infrared absorption and emission of CO2 and other gases.
Congratulations Judy: You are making progress, after 2500 Dragon comments: So now you agree with me that back radiation is not physics, just a phrase.
But it is a phrase that matters, because CO2 alarmism comes from inflating one-way net transfer by a factor of 10 by replacing it with the difference of massive two-way transfer = the difference between upward and downward longwave radiation.
It is like writing 1 = 11 – 10, and claiming that a 1% change will be 0.1 instead of 0.01.
This is how climate sensitivity is inflated from a realistic physically motivated non-alarming 0.3 C to an unphysical freely invented alarming 3 C of IPCC. This is the result using the phrase “back radiation”.
Do you accept this consequence of viewing “back radiation” and “greenhouse effect” only as a phrase and not physics?
Claes, there is much physics that makes your argument incorrect. Lets lose the back radiation terminology, we all agree on that.
Why? As has been pointed out we observe radiation from the atmosphere.
You are doing an Obama here
The goal ought is to slay the Dragon, not to play with it.
The phrase ‘back-radiation’ – while physically correct – has encouraged sloppy thinking and an unending distraction.
On the other hand an explanation in terms of heat flow and the role of clouds as thermal insulation is also correct and more intuitively sensible. Why not this?
I ought to have written “the role of the atmosphere as thermal insulation”.
Please keep in mind that any atmospheric insulation is in series with the nearly-perfect insulation of the vacuum of space. In addition, please keep in mind that temperature comes from matter…and there isn’t much in space, so it’s better to say space has no temperature than to say it has a low temperature.
The space is not an insulation for radiative energy transfer.
We have a succession of insulations, and we have also in part parallel energy transfer mechanisms so that one of them bypasses others.
In the succession we have
– energy transfer from surface to the atmosphere, which occurs mainly by IR and evaporation
– energy transfer in the atmosphere, which happens by IR, convection and transport of latent heat
– energy transfer from the atmosphere to the space, which happens solely by IR emission.
IR bypasses in part other pathways as the radiation can pass through the whole atmosphere or large parts of it without being absorbed in between.
I like the approach based on insulation, but unfortunately it becomes difficult to use for quantitative analysis. That’s partly due to the fact that part of the IR radiation can penetrate long in the atmosphere, but that’s also due to all issues related to convection and latent heat.
Finally the quantitative physical calculations are done in the same way independently of the language that we use in describing the processes in words. Finally only the formulas and the calculations can tell, what our theories imply.
Pekka Pirilä
I agree that we ought to use the most convenient and sensible quantitative models and methods for calculations. However, increased confidence comes from divergent methods which also produce identical results.
Nevertheless, the problem with the Sky Dragon seems more one of sloppy qualitative analysis and terminology. Ironically, this sloppiness is not always transparently obvious to those with technical backgrounds. It is, I believe, partly because the missing details are unconsciously supplied and also due, for example, to niche engineering jargon that is useful but may still carry misleading connotations. However, for non-technical people who are nevertheless critical thinkers, the sloppiness can cause abrupt, stubborn resistance to further learning.
BI2HS;
I’d be interested in your opinion of an alternate “thought experiment” analysis I’ve come up with.
1. Posit the Earth with current atmosphere, sans CO2, with temperatures cycling about a set “balance” point;
2. Instantaneously add 0.04% CO2, and mix well;
3. The effect will be to slow/lag some of the OLR on its path to deep space, and the atmosphere and surface will be heated by an effect amounting to IRP x Lag duration (a few dozen milliseconds?);
4. A new set point will be reached, and stabilize when the net OLR again matches DWIR (i.e., after the lag has passed.)
5. Now, instantaneously remove the CO2.
6. Over the duration of the lag, the equivalent of the heat energy accumulated in step 3 will dissipate into the deeps of space;
7. The system returns to step 1.
There are two, theoretically measurable, quantities to know, here. 1) CO2-intercepted OLR energy, and 2) lag duration.
Problems?
Correction to 4., above: when OLR again matches DWSW.
“There are two, theoretically measurable, quantities to know, here. 1) CO2-intercepted OLR energy, and 2) lag duration.
Problems?”
I doubt the affect would be measurable.
I doubt anyone would say there would be a measurable affect within days.
A volcanic eruption could have much larger affect, and doubt even that is measurable in days.
Doubt if you removed all greenhouse gas including water vapor, it would be measurable within days.
And natural variability could overwhelm the effect in terms of weeks and months. Though with all greenhouse gases removed, one probably see it within years. But without any clouds, global temperatures also could be significantly warmer. But if somehow kept the effects of clouds, it would cool the planet by a bit.
Doing something far more drastic, such as reducing the sun’s output by 10%, would also be difficult to measure within days [obviously in terms of “global temperature measurement”- rather than directly measuring the sun itself].
Hi Brian H-
Been away from the internet for a couple of days. Don’t know if you’ll get my reply.
Great poser – a trick question.
The biggest problem is that 0% CO2 implies not even single cell life. Not only would the albedo be drastically changed, but the overall lag duration would be measured in the billions of years while is evolving. This stretches the definition of long-term research project!
Of course there would be a rather dramatic impact on temp. if actual CO2 sensitivity was close that used by Dr. Pratt (i.e. well less than 2C).
BlueIce
Judy – I tend to agree with Eli on this point,. Back radiation is a very familiar term in legitimate climate discussions (Raypierre made this poiint on RC a while back), and conveys a fairly accurate picture of what is actually happening – infrared (IR) radiation is being emitted downward rather than upward, and in quantities sufficient to substantially alter surface temperatures. The problem with the term, as I see it, is that it fails to distinguish all downwelling IR from that portion that is redistributed downward (“backward”) from GHG molecules that have been excited as a direct or indirect result (thermalization) of IR originally travelling upward from the surface. There is an additional portion that was always headed downward in the form of solar IR, and which was intercepted by GHGs and again emitted downward at wavelengths characteristic of these molecules.
Even so, “back radiation” creates an accurate mental image overall, is widely used, and does not have a clearly superior alternative. “Downwelling IR” fails to indicate the role of GHG molecules in redirecting energy downward that would otherwise have escaped to space. I don’t see any compulsion to use the term “back radiation”, but neither do I see a reason to discard it.
Fred, downwelling longwave, apart from the negligibly small amount from the space background or sun, should all be considered emitted, the sources being GHG molecules, clouds if present, and dust. The history of these photons before their emission does not need to be taken into account, so reflection/redirection is not an important process in IR (though some small reflection may occur from cloud droplets since their emissivity may not be exactly 1.)
Jim – I think either term is fine. “Back radiation” appeals to me because it reminds readers that atmospheric GHG molecules can send a large quantity of IR back to earth when in their absence, all IR emitted from the surface would escape to space.
But, ‘back’ implies some kind of reflection when really it is emission. It would exist even if the ground was somehow at absolute zero and not emitting anything upwards.
Fred, you say “infrared (IR) radiation is being emitted downward rather than upward”. How’s that square with “isotropically”?
Isotropic emissions convert radiation that was emitted upward into radiation in all directions, about half of which is downward (at various angles).
Quite so. I was querying the words you used “infrared (IR) radiation is being emitted downward rather than upward” which could easily confuse if the context was not already understood.
Fred, I would like to understand in simple terms, what is the evidence that the angle of scattering of the outgoing IR photon is isotropic and therefore independent of the angle of incidence of the incoming IR photon?
Scattering is rare. What really happens usually is that IR gets absorbed and the energy transferred to thermal motion of the molecules by collisional deexcitation. At the same time many molecules are in excited state due to collisional excitation and a small fraction of those emits an IR photon isotropically to any direction. When the mean free path of the wavelength is short the rate of absorptions and the rate of emissions is equal far from the surface. Near the surface the rates may differ significantly as a part of the energy transfer from the surface to air.
The total power output is sigma/pi T^4; sigma T^4 means isotropic radiation.
“The total power output is sigma/pi T^4; sigma T^4 means isotropic radiation”.
Chris, no doubt it’s a commonplace that sigma T^4 means isotropic radiation but some definition of terms and their relevance here might help the interested reader to understand you.
Pekka Pirila… You say:
“Scattering is rare.”
Your assertion is nonsense. Statistically, scattering has the same chances of happening than absorption because they occur at the same time, to the same photon impinging on the same particle.
Show me a blackbody in nature, Pekka.
“Infrared radiation is being emitted downward instead of upward”
Even your attempt to start explaining this silly concept is confusing. So called backradiation is only one vector of all possible directions that GHG’s can emit energy and is slightly smaller quantitatively than the other directions. It is simply IR radiation. Giving it a special name distorts what it is supposed to do.
Backradiation isn’t emitted instead of, but along with. Trying to force the use of this abused term will continue the problems and is not necessary to explain the atmosphere effect that alledgedly BOTTLENECKS the OLR and causes AGW!!!
Let’s face it Judy: If you give up back radiation, then the greenhouse effect evaporates up into the atmosphere. How can you give up so easily? Now you have to tell precisely what physics makes my argument incorrect, my argument showing that back radiation is fiction, an argument which you now apparently embrace. So what physics make my argument incorrect? You understand that you will have to answer.
Claes, you don’t get it. I give up back radiation as a misleading phrase. I do not give up the infrared emission and absorption from gases like CO2. Or maybe you do get it, and your whole argument is sophistry rather than physics.
Bingo…I think we have a winner!
Dear Dr. Curry:
CO2 absorption and emission of radiations is a correct science. It is the claimed heat trapping effect of CO2 that is fiction. The mathematics used in the models accounts only for the heat trapping effects of trace gases such as CO2 and ignore atmospheric air. This is a wrong mathematics. Because carbon dioxide is an integral part of the air mixture and exchanges with the atmospheric air heat of absorption and radiation. The atmosphere as a whole, considered as air mixture, exchanges heat including radiation, with the surface for there is an interface between them. There can be no exchange of radiations between the layers of the atmosphere, as the radiative forcing theory wrongly suggests, because air mixture is homogeneous and there are no interfaces between air layers.
I vote for the latter. Judith, no matter how many times you try to explain this to him, Claes won’t get it. The whole greenhouse effect debate is a big word game for him, in which he likes to argue — he says — in parables. Claes’ arguments are nothing but sophistry.
Dr. Curry… You owe me two cents… Remember? You can send me my two cents via Pay Pal… :)
Dr. Curry, you don’t owe a humbug like Nahle anything. Like his fearless leader John O’Sullivan, Nahle pads his resume with many dubious academic and professional credentials and he will not provide any information by which they can be verified. A “scientist” who claims to have earned a “certificate” from the “University of Harvard,” is a laughable humbug.
I have no clue why people continue to entertain Claes. At least in Lindzen or Spencer’s case, they have a PhD in a relevant field to make people pay attention to them time after time.
Science is the belief in the ignorance of experts.
Anti-science is belief in the ignorance of ignoramuses.
Claes has some serious credentials
http://www.csc.kth.se/~cgjoh/
he is widely published and cited in applied mathematics.
Apart from his misunderstanding on this particularly topic, I can’t understand is why he would be hanging out with the skydragon group, and why he would pull a stunt like quoting me out of context after explicitly calling him on it here.
This kind of behavior is really destroying his credibility. Ignoring or insulting such people doesn’t make them go away. Identifying the flaws in their argument and then seeing them demonstrate untrustworthy behavior is the way to diminish any credibility they have.
It is good Judy that you understand that I am not a crank. I do not want to
misinterpret what you say or quote out of context. I just want you to show your cards. Will you do that?
Judith– PhD’s can still say the sun revolves around the Earth
From the point of view of normal physics, Claus’s position is incomprehensible. But I think he either rejects or is critical of a large mass of modern physics — including QM, SR, not to mention thermodynamics — and it may be easier to appreciate – if not agree with – his criticisms from that light. Perhaps part of the reason for his skepticism is the belief that a purely reductionist approach is not the best way to approach physics. If so, he is in good company (even if many do take vigorous exception). In this belief at least, there must surely be some resonance with the ideas of chaos and abrupt change in the climate system, which I’ve often seen discussed here.
The scientific term is surface downwelling longwave flux, sometimes qualified as broadband to indicate an integration over all IR wavelengths. There are measurements of this and papers about it. The science community has no dispute with the magnitudes of hundreds of W/m2.
I know, i discussed this extensively on the thread “why we have confidence in radiative transfer models” but this nonsense continues. Still trying to get to the bottom of why people don’t understand this. Or maybe this is all about sophistry and knocking down margin terminology like back radiation and greenhouse effect, that have been introduced to explain all this to nontechnical people.
I realized it is the terminology you are after. I wanted to just add that scientists have a different term, so you won’t find back radiation in papers, but if you look for downwelling longwave flux you find a lot of references to it as a known, understood and measured quantity.
“I know, i discussed this extensively on the thread “why we have confidence in radiative transfer models” but this nonsense continues. Still trying to get to the bottom of why people don’t understand this. Or maybe this is all about sophistry and knocking down margin terminology like back radiation and greenhouse effect, that have been introduced to explain all this to nontechnical people.”
No one thinks CO2 is responsible for “magnitudes of hundreds of W/m2”,
they aren’t that stupid, right?
And we know clouds are responsible for “magnitudes of hundreds of W/m2”.
And everyone realizes that the greenhouse affect has little to do with daytime temperature, and what it’s main affect is suppose to be on night time temperature and winter temperatures. Correct?
It’s also generally accepted that CO2 has little affect upon causing ice ages- if you half or double CO2 it doesn’t cause an ice age, and the idea that CO2 levels was originally considered as possible explanation for ice ages- was an incorrect hypotheses. Wrong because earth has been in cooling period for millions of years- that this long term cooling is major factor causing ice ages in the geologic record and this long term cooling is unrelated to CO2.
To help you answer my questions Judy: Do you think that “downwelling longwave radiation (DLR)” is also just a phrase? And not real physics?
Your readers want a clear answer.
Downwelling longwave radiation is better terminology to describe what is going on. Back radiation implies reflection of IR radiation which is incorrect. Infrared emission of infrared radiation is nearly isotropic, so some portion of the emission from atmospheric gases goes in the direction of the Earth’s surface, which is “down” if you are sitting on the Earth’s surface.
IR radiation is best visualized as an intrinsic emission of a gas at a given temperature with a given composition, plus anything transmitted through it from a background. These concepts come up in astronomical spectroscopy too.
Dr. Curry, try this one. We are all driving in our own cars, leaving town for a long weekend. As more people enter the highway, the traffic slows, as the traffic slows to a crawl, some of the motorists pull a u-turn and return to the city, and will try to leave again the next morning.
Very simple I know.
Leo, your idea is correct but applied at the wrong level of the atmosphere according to the IPCC and RealClimate. It is upper trop through strat where this alledgedly occurs and is due to the average radiation altitude increasing, lowering the average radiation height. This is what the models say, NOT a bottleneck at the ground!!! At the ground the temperature has no constraint and the GHG’s can keep emitting more to keep up with the increased emission of the surface!!!
Prof. Curry: They don’t understand it because they don’t understand that the warming in question is warming relative to a situation with a lower CO2 level, not warming relative to a situation with the same CO2 level. (I know, warming might continue for a while even if the CO2 increase was halted, until equilibrium was reached, but you can’t deal with that until you’ve dealt with the basic misconception.)
This doesn’t address the technically advanced arguments, such as Claes Johnson’s, even though, for all I know, they might depend on the same error, but I am convinced that some great majority of the people who believe that the greenhouse effect violates the 2nd Law of Thermodynamics are laboring under the misconception that I’ve indicated. Despite the difficulty of describing the difference between the two “kinds” of warming, I fail to see why it is not obvious that these people are missing it.
Why they are missing it is another question. I think part of the answer is that their critics are missing it, too. A scientifically informed critic will object to my idea by saying that warming is warming; there are no two kinds. OK, fine, but this misses the difference between warming relative to a situation with less CO2, etc., which is the same thing the “2nd Law” people are missing, so it can’t help them.
If you think I’m wrong, please comment.
“This doesn’t address the technically advanced arguments, such as Claes Johnson’s, even though, for all I know, they might depend on the same error, but I am convinced that some great majority of the people who believe that the greenhouse effect violates the 2nd Law of Thermodynamics are laboring under the misconception that I’ve indicated. Despite the difficulty of describing the difference between the two “kinds” of warming, I fail to see why it is not obvious that these people are missing it. ”
If you surrounded the sun with mirrors reflecting back the sunlight, can you heat up the sun?
Or are stars which surrounded by dust [star formation] hotter because of the dust?
Or why is the Sun interior so much hotter than it’s surface?
I suppose you look at that question in two ways, how about, why isn’t there runaway greenhouse affect with the sun?
gbaikie said: If you surrounded the sun with mirrors reflecting back the sunlight, can you heat up the sun? Or are stars which surrounded by dust [star formation] hotter because of the dust? Or why is the Sun interior so much hotter than it’s surface? I suppose you look at that question in two ways, how about, why isn’t there runaway greenhouse affect with the sun?
Your message is indented too far to have a “reply” thingie, so I’ll reply as if to myself. I’m not sure what surrounding the sun with mirrors would do. There’s probably a gotcha in the question (not that I think you know this), having to do with the fact that the mirrors would mainly be reflecting visible light and UV, and with what the sun is made of. I’ll guess that it would make the surface of the sun hotter, but that is a guess. With the dust, I’ll guess the same, with slightly more confidence, not much. Your last two question are just too too difficult for me.
Do you mean to be defending the idea that the greenhouse effect violates the 2nd Law? You don’t say. If it does violate it, it certainly doesn’t violate it in any easy-to-understand way. If you introduce “insulation” to the earth’s atmosphere, it changes the vertical distribution of temperatures. What’s hard to accept about that? Suppose you have a sphere surrounded by some material that’s transparent to UV. You shine UV on the whole affair, and the sphere radiates IR. Now you introduce a layer of material near the sphere that’s largely opaque to IR, or more opaque than the original material. The surface of the sphere will now be warmer, and the region of material outside that layer will be cooler.
“I’m not sure what surrounding the sun with mirrors would do. There’s probably a gotcha in the question (not that I think you know this), having to do with the fact that the mirrors would mainly be reflecting visible light and UV, and with what the sun is made of.”
[The sun mostly [about 90% of it’s total energy] emits infrared and visible light and these wavelengths would reflected by a mirror {99.9% of it}.
Sun is mostly hydrogen and helium.]
I’ll guess that it would make the surface of the sun hotter, but that is a guess. With the dust, I’ll guess the same, with slightly more confidence, not much. Your last two question are just too too difficult for me.
Do you mean to be defending the idea that the greenhouse effect violates the 2nd Law?”
No I just saying these similar issues. And in case with dust around a star- something which may be observable- and therefore have means of falsifying. But I believe the 2nd law would say that mirrors or dust would not increase the sun/star’s heat. Or at least the convention is to ignore this aspect.
In my opinion I would say when something is say 90 degrees there is less uniformity than what some might think there is, and to simplify one thinks of it as uniform. And therefore some heating is possible.
But I think the more important issue is the amount energy emitted from a “cold sky” is insignificant- on the order of the amount energy from Moonlight.
“Suppose you have a sphere surrounded by some material that’s transparent to UV. You shine UV on the whole affair, and the sphere radiates IR. Now you introduce a layer of material near the sphere that’s largely opaque to IR, or more opaque than the original material. The surface of the sphere will now be warmer, and the region of material outside that layer will be cooler.”
As said above UV isn’t a significant portion of energy from the Sun- and about 1/2 of Sun energy is infrared, but anyhow, a material opaque to infrared [or long wavelength infrared- and/or infrared spectrum of all objects on earth heated by the sun] will heat up and re-radiate energy. Perhaps you seen TV shows where people behind walls can seen- they are seen using a scope that can see infrared- the shows aren’t accurate but there some grain of truth regarding this aspect. Firefighter also use these scopes to see thru smoke.
And therefore “region of material outside that layer will be cooler” is incorrect. instead it would the opposite, it would be warmer [generally].
But I believe the main point is of article is that the colder sky doesn’t heat the warmer ground. And I agree with the obvious, the sky doesn’t radiate a significant amount heat [nfrared] to the ground.
gbaike:
[The sun mostly [about 90% of it’s total energy] emits infrared and visible light and these wavelengths would reflected by a mirror {99.9% of it}. …]
You’re right that I overestimated the ultraviolet. Eyeballing this graph, I get 10 percent UV andt 45 percent UV+visible). A lot would depend on the type of mirror, I think, but possibly that doesn’t matter to the question of whether mirrors surrounding the sun would heat it up. As I said, I think the answer is yes.
In my opinion I would say when something is say 90 degrees there is less uniformity than what some might think there is, and to simplify one thinks of it as uniform. And therefore some heating is possible.
I don’t understand. 90 degrees of what? Temperature? Elevation (above the horizon)? I don’t understand regardless of which of those I pick.
And therefore “region of material outside that layer will be cooler” is incorrect. instead it would the opposite, it would be warmer [generally].
Sorry, no.
But I believe the main point is of article is that the colder sky doesn’t heat the warmer ground. And I agree with the obvious, the sky doesn’t radiate a significant amount heat [infrared] to the ground.
How do you explain the fact that even strongly AGW-skeptical scientists, such as Richard Lindzen, Roy Spencer, and Lubos Motl, affirm that, ceteris paribus, an increase of the CO2 level does increase the surface temperature of the earth? If your argument is correct, this is astonishing, not “obvious.”
Do you think that Lindzen et al. are dupes or traitors? If they were, this would just about cancel your chances of figuring anything out. I’ve seen attitudes like yours in other areas, esp. economics. I’m referring to people who casually reject even what their own side’s experts claim. Often this is because they don’t know what their own side’s experts claim, but it’s not easy to see how this would be a factor in the question of global warming.
Back radiation is perhaps a good term at least for those that understand it. But it is a rotten metaphor, and for as long as people base argument on metaphor it will be problematic.
I am not sure that it is even a reasonable analogy for it may imply that it originates as a return flux whereas its origins are isotropic. It may also imply that it is directly the result of the outward ground flux, when it is only indirectly related being mediated by temperatures. Fluxes that originate in the atmosphere due to its temperature are sometimes referred to as the path thermal emissions. Part of the results of the integration of these emissions is called the back radiation. It may be that because people rarely refer to the path emission into space as the forward path radiation it seems that the back radiation is in some way unphysical e.g. one might query how it knows to go backwards. Also it may give the mental impression of a vertical beam whereas commonly much of it is oblique and weakest from the zenith.
We might do well to consider at what level terminology will be grappled with by those that are not well versed in the argot. By all means keep back radiation as a technical term but be prepared to forever fight off its metaphoric resonance.
Alex
This is part of vaughan pratt’s argument, that the terminology, and how it is (mis)interpreted, is a big part of the communication problem.
Why not call it atmospheric radiation? That’s what it is, after all.
Judith,
Yes indeed, it is also an unintended battle field. People are not so dumb as not to know how to exploit a wobbly scientific metaphor of which the GHE probably tops the all time listings but back radiation is climbing the charts.
It concerns me that I find little in the form of video recorded graduate/under graduate level lectures dealing with radiative transfer as I for one should like to watch them. Such lectures must occur annually and some universities are better at archiving such material than others, MIT and UC probably stand out as exceptions.
There comes a level where people must have some common basis of understanding and when a subject like the radiative properties of the atmosphere are underpinned by well understood physics perhaps the physics must be made available and freely so. If this is the important issue I believe it to be, those that put no trust in the illusory realm of the scientific metaphor should be exposed to the real science behind it and if the can’t hack that then be informed that there are intellectual hurdles to understanding however unintended and with the best will in the world those that can’t or won’t learn are at a major disadvantage.
Alex
Alex,
I have been thinking on writing up (just for fun or), how radiative heat transfer proceeds in gas. The theory is closely similar to that of thermal conductivity in gas, when the mean free path is not too long. Of course doing this effort would be wasted, if someone could provide a link to such a presentation, which is written sufficiently well, but I haven’t been able to find one.
Different wavelengths can be handled separately and the total effect is just the integral over wavelengths (or sum over bands).
Pekka,
while I remember I found this PPT:
file:///C:/Documents%20and%20Settings/Administrator/Local%20Settings/Temporary%20Internet%20Files/Content.IE5/9LSB5RCX/Barnet2%5B1%5D.ppt#679,15,“Curve of Growth” of a Molecule Band Model
That indicates an explanation of the linear, square root, and logarithmic regimes which I was so openly ignorant about and for wich you tried to correct me.
I think anything anyone with a muture understanding of the issues and perhaps teaching the subject can do would be useful. As to where and how to attract viewers you would just have to pug away at it. However if you have said all that needs to be in most cases a simple “here is my presentation go and read it might say a lot of effort in the long run, or it might not.
Alex
Pierrehumbert’s book contains related considerations, but not exactly, what I had in mind, which should explain some important things in simpler terms, but which has also restrictions in applicability that don’t affect Pierrehumbert’s formulation as much. Thus Pierrehumbert’s formulation is likely to be more useful for complete calculations of the the heat transfer through atmosphere taking into account the changing density and other important issues.
“I have been thinking on writing up (just for fun or), how radiative heat transfer proceeds in gas.”
Pekka,
I would find such a write up very informative. Please inform us if you do so.
Pekka, I would be keen to learn more. I can understand that CO2 and H2O do the absorbing but what does the emitting? Is it the GH gases or does the bulk of emission come from thermally excited N2 and O2? Does the emission happen instantaneously or is there some sort of heat capacity of the atmospheric gases?
If and when I get that ready, I’ll make a pdf file out of it, because it will contain formulas and some figures. I’ll put that in the file area of my site and give the link both here and on my own site. I may also ask, whether Judith is willing to have a shorter version with less formulas as a posting here, but that’ll depend on the form the text will have, when it’s (hopefully) done.
It’ll certainly not be a text book. Thus it can’t answer all related questions. The central idea is the close similarity between radiative heat transfer and conduction, when certain conditions are met, but I’ll certainly discuss to some extent also the problems of meeting those conditions. This issue is actually a subproblem, where I’m not sure, what I’ll finally conclude, i.e. I haven’t thought in full detail how far the approach similar to conduction remains practical. I’ll learn myself more about that, when I write it up, because that involves also some work with the mathematical formulation of the conditions.
The easy part is, what happens safely inside the troposphere for radiation of high absorptivity/emissivity. That’s already interesting enough in my opinion, but, what happens to the mathematics when the mean free path is so long that atmospheric density or the temperature gradient changes significantly over that distance, that I haven’t checked in detail.
The overall role of the radiative energy transfer in understanding the atmosphere is an issue that I must discuss to some extent, but that’s an area that I certainly cannot handle in full detail, but will be limited to some semiquantitative statements at best.
Another open question is, how much I’ll include such issues as those dlb asked. The main part of the text will certainly take answers to those questions given, and I don’t know now, how much effort I’m willing to put in justifying the starting points rather than just stating them.
If the text will be discussed here or elsewhere, that’ll offer opportunities for further questions and answers.
curryja, 8/13/11, 11:50 am, Vaughan Pratt
How far should we go when we lose the back radiation terminology ? We will have to throw out Kiehl & Trenberth, Earth’s Annual Global Mean Energy Budget, 2/1/1997. AR4, FAQ 1.1, Figure 1, p. 96. And since The term “radiative forcing” has been employed in the IPCC Assessments to denote an externally imposed perturbation in the radiative energy budget of the Earth’s climate system. (TAR, ¶6.1 Radiative Forcing, ¶6.1.1, p. 353), we will have to throw out radiative forcing, too.
You imply we should rely on radiative transfer instead. 8/13/11, 10:10 am. Yet, the uncertainty in RF is almost entirely due to radiative transfer assumptions. AR4, ¶2.3.1, p. 140.
Your recommendation looks like throwing out the baby and keeping the bathwater.
Yet you wrote, Climate models calculate radiative transfer and fluxes in grid cells all over the globe in response to the temperature and humidity profile, cloud characteristics, and gaseous and aerosol composition at the grid cell at that particular point in time (multiple calculations are made in each grid cell for each day in the model integration.) And then recommend the thread, Confidence in radiative transfer models. 8/13/11, 11:14 am.
We did indeed have a nice dialog on radiative transfer there. The result, however, instilled no confidence in this highly precise but impossibly inaccurate theory. Indeed, what distilling that thread might show is the reason why RT is the biggest source of error in RF. The accuracy of RT is limited by the accuracy with which one can characterize the atmosphere, including its lapse rates and CO2 distribution. It is further limited by the fact that it is non-linear, so that the average flux in a cell cannot be determined from the flux for an average atmosphere. Perfecting the atmospheric model is a waste of time.
As you point out on both scores, GCMs may not start with a global average temperature but they do require a temperature and humidity profile. If you mean a daily average temperature and humidity, the diurnal effects alone should make the problem of determining an average radiative flux prohibitive. Then throw in the confusion over the CO2 distribution in the atmosphere! The on-line MODTRAN routine makes CO2 proportional to atmospheric pressure, based presumably on the well-mixed assumption. The AIRS results show that it is far from well-mixed, but regardless, RT needs the CO2 lapse rate to be known accurately just to get the radiation instantaneously right.
The ugliest part of all this is that the RF model can’t get the shortwave radiation right, back radiation or not. And that as IPCC admits, that error is as great as the whole climate sensitivity estimate based on the simplest theoretical grounds. 4AR, ¶1.5.2 Model Clouds and Climate Sensitivity, p. 114.
The core problem with the back radiation concept is that one-way radiation doesn’t supply heat. Thermodynamics defines radiant heat as the net radiation between objects. Heat is what changes thermal energy, not as some claim, back radiation. E.g., Fred Moolten, 8/13/11, 12:03 pm. K&T, on the other hand, got that part right in their hybrid budget: for thermodynamic modeling, radiation must always appear in pairs, up and back. The net in their budget is 66 W/m^2, about a fifth of what it receives from the Sun, and the net was sufficient for the budget.
That the atmosphere might heat the surface on some global scale is silliness, no matter who said it or whether it was published. Neither the atmosphere nor CO2 is a source or a sink. One could model either as a source or sink, but the model would have to take into account the appropriate heat capacity to have any predictive power. As it turns out, those heat capacities are negligible. The atmosphere is a blanket. AR4, FAQ 1.1, p. 95. It’s a wet blanket to AGW, including CO2. As a blanket, it is a resistance to heat, not radiation. The atmosphere acts as a resistance to the cooling of the surface through radiation to deep space.
When Vaughan Pratt pointed his IR thermometer at space and the surface, he was sensing a net radiation for each. He was sensing the energy in the form of heat as it impinged on the detectors in his thermometer, whose microprocessor then calculated the impinging radiation from an algorithm using an estimate of the detector temperature. His device converted that impinging radiation to temperature using Stefan-Boltzmann’s perfectly nice and useful equation as if the detector were at 0K and using some sort of standard or selectable emissivity. We don’t measure the theoretical concepts of up and back radiation. We don’t sense them. We estimate them always from intercepted energy. And that is how they work with Earth.
I endorse your notion to throw out back radiation, but don’t stop there. We should return to the lost art of estimating climate with a thermodynamic model. In that domain, heat is a flow variable, the greenhouse gases are a variable, passive resistance, and feedback can be modeled rationally and productively.
Jeff, that is extraordinary common sense. Thank you.
Jeff – I’ve read through your long discourse, and except for a variety of undocumented assertions, I find nothing in it to contradict the observationally confirmed magnitude of downwelling longwave radiation (colloquially “back radiation”). In addition, you are incorrect in asserting that this IR can’t change the thermal energy of the Earth’s surface. Of course it does. The fact that “radiation appears in pairs”,and the net effect is paramount, doesn’t contradict this principle – the back radiation changes the net as long as there is an energy imbalance, and this results in a rising temperature (more thermal energy in the oceans, for example), until balance is restored at a higher temperature.
Fred Moolten, 8/13/11, 3:27 pm, Vaughan Pratt
Since you couldn’t be specific about my undocumented assertions, you leave me to guess where you need help. Note that previously I did provide documentation, just not enough for you, meanwhile you chronically provide none. These references, though, might fill the bill.
The gain or loss of internal energy, equal to the difference between the energy of the thermal radiation which is absorbed and that which is radiated, is called heat. Bold added, Zemansky, M. W., Heat and Thermodynamics: An Intermediate Textbook for Students of Physics, Chemistry, and Engineering McGraw-Hill, Fourth Ed., 1957, p. 105.
We have for the heat transferred by radiation between a body at the temperature θ and walls at θ_W, is Q_dot = A*α•σ*(θ^4 – θ_W^4), where α refers to the temperature θ. Id., p. 106. Note: the radiation from the walls of the assumed enclosure is the back radiation.
You wrote, the observationally confirmed magnitude of downwelling longwave radiation (colloquially “back radiation”). In addition, you are incorrect in asserting that this IR can’t change the thermal energy of the Earth’s surface. This is wrong on a couple of counts. As I explained at 3:10 pm, what we observe is not back radiation, but instead a heat flux. Secondly, your assertion that back radiation changes thermal energy violates the thermodynamic definitions cited above.
Your wrote, the back radiation changes the net as long as there is an energy imbalance, and this results in a rising temperature (more thermal energy in the oceans, for example), until balance is restored at a higher temperature. Balance is not restored. Earth has no preferred thermal state as long as long as TSI and gravitational forces exist. This is a big error repeated in the AGW model. It was an error expressly avoided by G.S. Callendar when in 1938 he published what became known as the Callendar Effect. Earth’s climate is stabilized and regulated by albedo, cloud albedo in the warm state (Callendar), and surface albedo in the cold state (Glassman).
Equilibrium does not exist because it is convenient for the analysis. It must be explicitly invoked by the existence of a principle of physics. Minimum kinetic energy leads to equilibrium for lossy mechanical systems. Minimum torque leads to equilibrium for a balance scale. And for climate, the Second Law of thermodynamics leads equilibrium, but you have to include the Sun and deep space along with Earth’s climate and wait forever.
When last I tried to explain this error of yours with equilibrium (6/7/11, 12:35 pm, Toward sane policies thread), and more, all you could muster up was this crack: Jeff–I can see the medication isn’t working. My own sane policy informs me not to expect a more intelligent response this time. Nonetheless, my Rx for you is a dose of Zemansky. When you just repeat IPCC dogma, you inherit all its many errors.
Jeff – You repeat the erroneous assertion that back radiation can’t change the thermal energy in the surface (including the ocean). Since it can and does, and since understanding that is critical to understanding the greenhouse effect, I believe your other conclusions become largely irrelevant. There is no violation of thermodynamics. When more back radiated energy enters the ocean from an increase in CO2, the ocean’s thermal energy increases. Its temperature also increases and so the ocean radiates more energy outward, but if the back radiation has increased, restoring a radiative balance requires the upward radiation to increase, which can only happen with a temperature rise. Indeed, it would violate thermodynamics for an increase in incoming absorbed energy to be matched by an increase in outgoing energy without an increase in temperature. That would permit two bodies with the same composition, temperature and emissivity to radiate different amounts of energy.
I think this is well enough understood to require us not to waste too much more time on it.
‘It is true that much of the atmosphere is colder than the surface but the point about greenhouse gases is that they reduce surface cooling by reducing the outgoing long wave radiation to space which is close to absolute zero. They do this by absorbing the outgoing radiation and then emitting isotropically.’ From Tom above
An atmosphere warmed as a result of less emission to space – emits in all directions including down and reduces the net IR up from the surface. Surface cooling is reduced – including in the oceans.
Fred Moolten, 8/13/11, 5:09 pm, Vaughan Pratt
FM: You repeat the erroneous assertion that back radiation can’t change the thermal energy in the surface (including the ocean).
Assertion: 1. a positive statement, usually made without an attempt at furnishing evidence
2. the act of asserting World English Dictionary
I made no such assertion. I gave you book, chapter, and verse from first year thermo on what heat and radiant heat are, and where thermal energy and back radiation do and do not fit. 4:47 pm.
FM: The Earth receives thermal energy from the sun and from IR back radiated from the atmosphere at altitudes varying from less than a millimeter up to many kilometers. 12:03 pm.
See? No evidence; not even an attempt to supply evidence. THAT is an assertion.
You are back-radiating; i.e., providing no energy to the dialog.
Fred,
“Since it can and does, and since understanding that is critical to understanding the greenhouse effect, I believe your other conclusions become largely irrelevant.”
You assert that understanding the misnomer Backradiation is critical to understanding the Greenhouse effect. I declare it is NOT critical to understanding the Greenhouse effect as put forward by the IPCC and RealClimate.
This is what THEY claim:
http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/
Notice all the action has happened before there is a significant rise in surface temperature??
This is why SOME of us DENIERS claim there IS NO GREENHOUSE EFFECT!!! The physics described here is all about average radiation altitude and average radiation temperature, NOT the surface conditions that aren’t affected until Greenhouse is well advanced!!!!!
Why are we still arguing over the downwelling part of GHG’s IR radiation mislabeled Backradiation?!?!?!?! Is this the new communication methods, keeping the argument about something not integral to the THEORY?!?!?!?!
OR did someone decide to change the theory and the models without telling anyone??
First of all because downwelling IR radiation really does exist. And, second of all, because it is useful to understand the energy balance in simple models of the greenhouse effect before graduating to more complicated models.
However, I for one have continually pointed out that what the greenhouse effect really relies on is the notion that the net heat exchange by radiation of two object depends on both of their temperatures and not the interpretation (well-supported by experiment) that this represents two “streams” of radiative energy. [And, despite Claes’s false claims, changing your interpretation does not change the quantitative effect that you calculate because the effect is not calculated as some percentage perturbation but rather as an actual magnitude.]
Mr. Fred Moolten, It sounds to me that the current science is only able to tell us the difference between a ‘balance spring’ & the ‘escapement’, but still can’t tell us what time it is, for sure.
Jeff Glassman says:
(I put in quotes because I don’t know how to do italics like he did.) I think this illustrates how Jeff Glassman uses selective quotation to support his point of view. Clearly, he wants us to believe that there is some huge uncertainty regarding the RF due to these radiative transfer assumptions. However the fuller text around that selective quote actually reads:
and from the table caption footnote:
So, it turns out that the radiative transfer assumptions contribute to errorbars of +/-10% at the 90% confidence level. (And, the point of the note that the uncertainty in the radiative transfer is the biggest contributor to the uncertainty in radiative forcing is just made to make the point that changes in radiative forcing due to changes in concentrations are known more accurately than one might infer if one thought the concentrations values were the main source of the uncertainty.)
So, I think this little exercise illustrates how a true skeptic would be extremely unskeptical to believe anything that our friend Jeff Glassman writes on face value.
Joel Shore, 8/13/11, 10:10 pm, Vaughan Pratt
I do indeed use selective quotes to support [my] point of view. Only a fool would do less. If only all the champions of the lost cause who post here would do the same. I quoted accurately, and unlike your post, I put no spin on the quotation.
You accurately quoted IPCC’s restricted context for that quote, but what you quoted was hyperbole and brochuremanship. IPCC did claim that the 90% confidence limit on a list of radiative forcing calculations was about 10%. By using this language from the art of statistics, IPCC appears to convey the impression that the radiative forcing calculations are accurate to within 10% at the 90% confidence level. However, IPCC provided no data for assessing RF accuracy.
The most that the data can mean is that the models are mutually consistent within 10% for the LLGHGs after a concerted undertaking of model and radiative transfer intercomparison projects (AR4, ¶1.5.3 Coupled Models: Evolution, Use, Assessment, p. 118; ¶10.2.1.4, p. 758): e.g., AeroCom, AMIP, C^4MIP, CMIP, EMDI, MIP, OCMIP, PCMDI, PILPS, PMIP, RTMIP, SIMIP, TransCom 3. While IPCC noted efforts to maintain independence of model outputs during intercomparison (AR4 ¶1.5.3, p. 118), that the models have not subsequent to the intercomparisons converged to better than 10% just on LLGHGs is surprising.
The passage you cited casts radiative transfer in the best light possible by citing results for radiative forcing calculations on LLGHGs. That is a small part of the application of RT. The dominant GH gas is water vapor (AR4 FAQ 2.1, p. 135), which is neither long lived (it’s not on the long-lived lists) nor a radiative forcing in IPCC models (AR4 ¶TS.2, p. 23.). IPCC treats water vapor as a feedback so the GCMs can release water vapor to amplify the CO2 effect. AR4 FAQ 1.3, p. 116. Even configuring CO2 as an LLGHG, not enough accumulates in the atmosphere to cause the desired warming.
In addition to its amplifying effect, water vapor by itself is more than twice as important as a GHG than is CO2, contributing 60% versus 26%. Kiehl & Trenberth, 1997, Table 3, p. 203, cited at AR4 ¶3.4.2, p. 271. Note also that K&T call water vapor absorption of longwave radiation a forcing (id.), and that their estimates are based on radiative transfer (id., p. 200).
The discrepancy in models caused by radiative transfer is not just the 10% effect ascribed to LLGHGs. And as far as that goes, CO2 is the only anthropogenic, radiative forcing LLGHG that counts, contributing 1.66 Wm^-2 out of a net of 1.6 Wm^-2. AR4, Figure TS.5, p. 32. In one intercomparison of total predicted longwave forcing, IPCC identified only RT as the culprit in model discrepancies about five times as large as what it gives for present day CO2 alone.
The radiative forcings by long-lived greenhouse gases computed with the radiative transfer codes in twenty of the AOGCMs used in the Fourth Assessment Report have been compared against results from benchmark line-by-line (LBL) models. The mean AOGCM forcing over the period 1860 to 2000 agrees with the mean LBL value to within 0.1 W m–2 at the tropopause. However, there is a range of 25% in longwave forcing due to doubling atmospheric CO2 from its concentration in 1860 across the ensemble of AOGCM codes. There is a 47% relative range in longwave forcing in 2100 contributed by all greenhouse gases in the A1B scenario across the ensemble of AOGCM simulations. These results imply that the ranges in climate sensitivity and climate response from models discussed in this chapter may be due in part to differences in the formulation and treatment of radiative processes among the AOGCMs. Bold added, AR4, Ch. 10 Executive Summary, p. 751.
IPCC doesn’t provide the model data for these various discrepancy reports. In a rare instance that is instructive and relevant, IPCC did report model variability. It reported the radiative forcing for a doubled CO2 concentration, F_2x, from 19 models. AR4, ¶8.SM, Table S8.1, p. 8-73. It reported the climate sensitivity, T_2x, from the same set. AR4, ¶8.6.2.3 What Explains the Current Spread in Models’ Climate Sensitivity Estimates, Table 8.2, p. 631. The radiative forcing, F_2x, varies between 3.09 and 4.06 Wm^-2, a range of ±13.6%, and is approximately uniformly distributed (P = F – 3.12). Likewise the climate sensitivity, T_2x, varies between 2.1 and 4.4ºC, a range of ± 35.4%, and is approximately uniformly distributed (P = 0.40 * (T – 1.88)).
Uniform distribution is the condition of maximum entropy. Because the outputs of these models are approximately uniformly distributed, the underlying AGW algorithm is little more than a random number generator. That is what explains the current spread.
The story with water vapor doesn’t end there. IPCC reports that cloud feedback is the largest uncertainty in the GCMs, and that it can produce another 100% variation under the simplest theoretical grounds. AR4, ¶1.5.4 Model Clouds and Climate Sensitivity, p. 114. IPCC wants you to believe that its models agree within 10% at 90% confidence.
Satellites are now providing the first check on model accuracy, as opposed to variability. As reported and discussed here on the Lindzen and Choi threads, empirical climate sensitivity is running about 0.7 ºC, not 3 ºC, and well below IPCC’s likely range of 2 to 4.5 ºC. AR4, SPM, p. 12. The GCMs which operate under the radiative forcing paradigm, augmented by radiative transfer, are being invalidated by remote sensing. Radiative transfer remains the largest source of error, but after IPCC’s failure to account for cloud feedback.
These conclusions are not as you say [my] point of view. This is not a theological matter of believers vs. skeptics (nonbelievers) as you imply. The conclusions are a deduction from evidence, analysis and model building. It’s a matter of one scientist against the self-proclaimed consensus. It is a skeptic against a conspiracy.
Mercy buckets; well said.
I am reminded of the citation of Schack by G&T:
[bold emphasis added].
Definitively unmeasurable means irrelevant, IMO.
I agree the phrase matters and it is not a very useful phrase. What mystifies me is that most people understand the role of water vapor but totally lose it with CO2. Part of the confusion I believe is the frame of reference used. On the surface CO2 is lost in all the other action. From space you only see the net. At the tropopause CO2 is significant upward not so much downward. You need to travel through the layers of the atmosphere to “see” the changing significance of various gases and the changing transmission window clarity that limits outwards LWR.
Claes:
Not sure how you calculate things. “CO2 alarmism” does not inflate “one way net energy transfer”. Energy transfer is a well studied field. Many things that work are designed based on the science. The values that the climate alarmists developed are very VERY close to those used in other fields, particularly combustion engineering. If you are going to question things like this and posit such massive errors, you must then explain why they are NOT so out of whack in a blast furnace. Because if the climate alarmists are so wrong, then so are the combustion engineers. And something else decreases the amount of coal you need to create a ton of steel. Something that varies with a one to one direct and continuous relation to atmospheric CO2 concentration. You must also be able to explain why temperatures in a hot pipe in air change the way they do, because right now, we can successfully predict this using values for CO2 absorbance almost identical to the values that climate alarmists use.
Radiant energy absorption from an energy source by intervening gases causes the intervening gases to warm up. These warmer things (which were already radiating energy) radiate energy at a higher rate. If you want to call that ‘back radiation’, so be it, but please don’t embarrass yourself and claim that climate alarmists exaggerate this by a factor of 10. They don’t exaggerate it at all.
If you go to my blog, you will see a paper that uses combustion engineering methods to estimate climate radiant transfer impacts. You will see that they are nearly identical to what the climate alarmists use.
I am strongly on the skeptic side. Your assertions make Al Gore look reasonable and that isn’t good for the cause.
See my citation above of the G&T citation of a themodynamic engineer’s observation: “the radiative component of heat transfer of CO2, though relevant at the temperatures in combustion chambers, can be neglected at atmospheric temperatures.” So your admission that you use values identical to those climate alarmists use is to say the latter are violating boundary conditions.
Professor Claes Johnson: “It is like writing 1 = 11 – 10, and claiming that a 1% change will be 0.1 instead of 0.01.”
Indeed, the GHE is a concocted superfluity that is sustained merely by statistical shenanigans by charlatans who have no real world evidence evidence to back their claims. As Alan Siddons has repeatedly stated:
” Predicted earth emission without a greenhouse effect: 239 W/m²
Actual earth emission WITH a (supposed) greenhouse effect: 239 W/m² “
Look, if you guys are competing for who can make the stupidest statement, could we please just call it a tie? Do you guys understand absolutely NOTHING about the science you are critiquing? I can’t believe you (or at least those of you who have a science background) are really that ignorant and must therefore conclude you are purposely deceptive. Shame on you!
Joel, John O’Sullivan and his fellow Slayers are not trying to understand science. They are trying to create public misunderstanding and mistrust in science through the deliberate spread of falsehoods.
Just look at the outrageous falsehoods in John O’Sullivan’s “science report” last month — which was a shameless fabrication:
John O’Sullivan: Shock News: Disgraced Climategate Scientist Made Top UN Weatherman”
Friday, July 1st 2011, 10:22 AM EDT
http://climaterealists.com/index.php?id=7970
“Jim Salinger, one of the scientists suspected of criminal misconduct in the Climategate scandal has been elected to the prestigious role of President of the Commission for Agricultural Meteorology of the World Meteorological Organization (WMO). Climate skeptics are aghast at the news.”
As Gareth Renowden pointed, South Korean Byong Lee — not Jim Salinger — was elected president of the WMO’s Commission for Agricultural Meteorology for a four-year term in 2010.
http://hot-topic.co.nz/so-many-lies-and-the-liar-who-tells-them/
Jim Salinger had been elected president of the Commission for Agricultural Meteorology in 2006 — years before the so-called “Climategate scandal.”
And O’Sullivan piled on the lies: “In an ironic twist it’s the Kiwi government department now trumpeting his new WMO appointment on the NIWA website.”
And he got fellow Sky Dragon Slayer Joe Olson to chime in: “Joe Olson of the Slayers group of skeptics was quick to comment, ‘This is how the greens recycle their ‘waste’.”
And then topped it off with an even more outrageous whopper:
“Salinger remains a suspected accomplice in the tight knit international clique of climatologists involved in the data corruption scandal at the University of East Anglia (UEA), England. Commenting on that ongoing criminal probe, Senior Investigating Officer (SIO), Detective Superintendent Julian Gregory said: ‘This has been a complex investigation, undertaken in a global context and requiring detailed and time consuming lines of enquiry. Due to the sensitivity of the investigation it has not been possible to share details of enquiries with the media and the public and it would be inappropriate for us to comment any further at this time.’”
NO. Salinger is NOT a “suspect” in any criminal probe. Detective Superintendent Gregory’s comment, which O’Sullivan misquotes, was referring to his office’s investigation of the the illegal theft of emails from the University that were used to perpetrate the so-called Climategate Scandal.
http://www.telegraph.co.uk/earth/environment/climatechange/7594656/Police-question-climategate-information-seekers.html
Clearly, O’Sullivan and his partners are not misunderstanding climate science — they are misrepresenting it in to deceive the public to spread doubt and mistrust.
I always thought that if fire/firebricks had been used as an analogy, it would have been much better than the glass/greenhouse one.
For the thermometer I am looking at right now, the only thing it essentially shows is the temperature of the (nearly) 1,000,000PPM of N, O and Ar. I ask myself…how did this gas get to this temperature? Heat was conducted into it and it was convected to my surroundings. Sure, there is a thermal path to from CO2 to the rest of the atmosphere, but this path is bidirectional and it is more accurate to say that nearly 1,000,000PPM controls the the temperature of the 390PPM…rather than the reverse.
I know radiation is a mysterious thing…how does this spooky, instantaneous, action-at-a-distance really work? Still, the idea that you could “do” something significant (measurable) with weak, diffuse radiation–like increase the surface temperature of the earth by nearly 10%–is just plain silly.
“Greenhouse” gases can delay outgoing radiation a little. How long? Microseconds? Milliseconds? How do you conflate the effects of this small time delay into higher and higher record temperatures?
First go look up the zeroth law of thermodynamics. Let Eli Google that for you. Also allow Eli to point you to devices that measure temperature by radiation
Second, arguments from personal incredulity are not very impressive from the credulous.
Third, for all practical purposes, the delay in emissions within the wavelengths at which greenhouse gases absorb is forever. There is zero probability that a photon emitted from the surface at a wavelength that CO2 or H2O absorbs will make it into space. The photons in that region that are emitted to space come from vibrationally excited molecules high up in the atmosphere.
I urge you to look again at Vaughan Pratt’s statements. He cites ONE meteorologist as his authority. Yet the term ‘atmospheric greenhouse effect’ does not occur in any fundamental work involving thermodynamics, physical kinetics, or radiation theory.
Moreover, it’s hard to take anything that Arthur Smith (Eli Rabbett) writes as serious after the debacle of his efforts in Halpern et al. (2010). No journal would publish these GHE devotees because their work contains a fatal flaw after the authors introduced effective quantities by averaging over the entire globe (see their Eqs. (7) to (9)) with violations of basic rules of calculus. Their equations (3), (6) to (8), and (11) are flawed by dimensional inaccuracies. All rebutted via peer-review here:
– Reply to “Comment on ‘Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics’ by Joshua B. Halpern, Christopher M. Colose, Chris H0-Stuart, Joel D. Shore, Arthur P. Smith, Jorg Zimmermann”
(International Journal of Modern Physics B, Volume 24, Issue 10, pp. 1333-1359, April 2010)- Gerhard Gerlich, Ralf D. Tscheuschner
Bottom line: back radiation does not supply ANY additional heating to our planet and GHE adherents are refuted for their bogus arguments that our atmosphere operates as a ‘closed’ system when in fact it is an ‘open’ system.
Thus energy in = energy out or boom! As Alan Siddons has repeatedly stated:
” Predicted earth emission without a greenhouse effect: 239 W/m²
Actual earth emission WITH a (supposed) greenhouse effect: 239 W/m²
– Reply to “Comment on ‘Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics’ by Joshua B. Halpern, Christopher M. Colose, Chris H0-Stuart, Joel D. Shore, Arthur P. Smith, Jorg Zimmermann”
(International Journal of Modern Physics B, Volume 24, Issue 10, pp. 1333-1359, April 2010)- Gerhard Gerlich, Ralf D. Tscheuschner
Back radiation does not supply ANY additional heating to our planet and GHE adherents are refuted for their bogus arguments that our atmosphere operates as a ‘closed’ system when in fact it is an ‘open’ system.
The term ‘atmospheric greenhouse effect’ does not occur in any fundamental work involving thermodynamics, physical kinetics, or radiation theory. Rabbett et al’s paper relies on guesstimates about the scientific properties involved to ‘calculate’ the chaotic interplay of such a myriad and unquantifiable array of factors that is beyond even the abilities of the most powerful of modern supercomputers.
Great, John, so you have read their reply. Could you kindly explain for the benefit of all of us how they explain their claim that the atmospheric greenhouse effect violates the 2nd Law. Please in particular focus on the part where we show via simple models of radiative transfer that the reasons that they seemed to claim that the Second Law is violated are nonsense…Good luck finding it though!
No, John O’Sullivan, No science journal anywhere will publish ANYTHING you and your fellow denier’s write about global warming. Now why is that? Oh, right, it’s that evil conspiracy like this guy says:
http://www.ucsusa.org/assets/images/si/science-idol-2011/web-UCS2012calendar_jbilicki.jpg
While we’re on the subject of scientific credibility, let me point out that we’re still waiting for YOU to provide evidence for ANY of the professional and academic credentials you claim in your resumes.
You say your representing fellow Slayer Tim Ball in the Supreme Court of British Columbia against libel charges brought by climatologists Andrew Weaver and Michael Mann. How is that possible since you’re not licensed to practice law in British Columbia?
Ahh, Brer Rabbett also showed up. Why are you also not arguing the RC and IPCC theory that is about the upper atmosphere?? The so called backradiation is a side show. Is that the real scam??
Ken:
In radiant heat transfer calculations (better described as energy transfer), we use a value called “Path Length”. This is the product of partial pressure of the gas and distance. Thus a very concentrated gas over a short distance will have the same path length as a very dilute gas over a very long distance. For CO2 in the atmosphere, you come up with a path length somewhere between 200 to 300 bar cm (my estimate is 270 bar cm at 400 ppm). This is actually very high. 500 bar cm is about the concentration at which saturation occurs and there is no further impact from increased CO2. As such, from a radiant heat transfer point of view, there is a lot of CO2 in the atmosphere. What is really interesting is the fact that if there were a lot less CO2, small changes would then have a much larger effect. It is only because there is so much CO2 that the effect of CO2 change we are talking about is relatively small.
I tutor university undergrads in physics. The first lesson I teach is: Common sense is your enemy.
Cheers
JE
Hi John. I don’t dispute radiant energy is diffused by CO2 and that every CO2 molecule will radiate based on its temperature. However, how did the molecule get its temperature? Sure, some of its temperature comes from being tickled by IR, but here on the earth’s surface where I care about things, the overwhelming control is via collision with nearly 1,000,000PPM of N, O, Ar, H2O, etc. Frankly, I don’t care about the atmosphere where it is very cold and highly rarefied. The earth’s surface is hotter because the thin air temp at cruising altitude is -45 instead of -55C? Right-o.
The idea of a TOA human-controlled outgoing radiation modulator is very silly. Radiation is fun to study and fun to think about, but using diffuse, low-power IR radiation for something useful like increasing the earth’s surface temperature by almost 10%? My gosh, cut back on the herb you’re stuffing in your magic pipe, okay?
For every climate science explanation, step-by-step, of how human-caused warming works, there is always and inevitably a hand-waving stage. I’m tired of hand-waving by bright, fully-indoctrinated people who want to explain to me, a tired and grumpy old electrical engineer, how heat transfer works. I get paid very well because I know how heat transfer works, thank you very much.
Ken:
The “forcing” quoted in the IPCC reports can be calculated by engineering methods used to design things like blast furnaces. The values are pretty close.
I have NO hand waving stages in my math. Please visit my blog and read the paper at the top. It describes a method of calculating “forcing” that is independent of that used by the climate scientists. You will see that the methods used to design things that work, such as a blast furnace, provide results that are very similar to those used in the Global Circulation Models. It also explains what 300 ppm CO2 is a LOT of CO2, from a heat absorption point of view.
I too get paid very well. I get paid to perform heat transfer calculations. I’m a grumpy old metallurgical engineer. That’s an argument from authority though and is not relevant to the topic.
We are not talking about the method that causes the surface temperature to be 10% warmer than a black body radiator would be. We are talking about whether there is a greenhouse effect due to CO2.
If you want my opinion on why we are 10% warmer than a black body radiator, I believe it is primarily the oceans that absorb and retain sufficient energy to account for the increase and the atmosphere has little impact on it. But that isn’t the topic at hand.
Cheers
JE
Claes: I thus agree with Vaughan.
Great. This ought to qualify me as a mediator for whatever might be the biggest point of disagreement between you and Judy. Not right now though, maybe in a few days.
“You’ll get nowhere attacking what skeptics say, you have to address what they’re thinking…”
Oh yes, why argue with facts when you can attack the person presenting them…
The pretension of “knowing” what or how one thinks is quite arrogant.
And just to prove my point – I think your assumption that CO2 natural release is constant is wrong (“Preindustrially this flux was in balance and CO2 was not under any great pressure to change rapidly in a single century” – where did you get this idea from?), and also wrong is your notion that nature cannot cope with extra few PPM a year properly (extra plant growth does it quite well actually).
It is obvious that Earth has seen much higher rates of CO2 with no catastrophic effects. What brings a reasonable person to think THIS time is different? I wonder.
Eyal Porat:
So, you think that sea levels tens of meters higher and completely different climates around the world are no big deal?!? On that scale, I suppose that terrorists flying planes into buildings wouldn’t even register. So clearly, all the money we are wasting on fighting terrorism is silly…After all, the Earth has seen terrorists fly planes into buildings with no catastrophic effects.
Tens of centimeters not meters. Ten of meters was debunked on another thread a few weeks ago.
Kermit – Differences of 125 meters (not centimeters) have been associated with different climates in the past.
Kermit:
Many tens of meters. The present barrier coral reefs are direct evidence of this. They are located far from shore in deep water even though coral needs shallow, warm water to thrive. They started growing where they are when the glaciers were at a maximum. Were all the glaciers to complete their melting that started many thousands of years ago, the net remaining increase in sea level would indeed be more than 100 meters. Only time will tell if this global warming trend, started many thousands of years ago, will continue and cause the remaining glaciers to fully melt, or if a new ice age will start. Both alarming prospects if you ask me.
Let’s be accurate (if not precise).
Cheers
JE
The average rate is about 3.1 mm per year based on 1993 to 2003 and its not increasing since that time. Even if that did increase to 4 mm per year, which would quite an unrealistic increase, that would take 250 years to increase 1 meter. Daily high tide to low tide variation is way more than that. These sorts century and decade changes are nothing new to civilization.
Go to the older threads like http://judithcurry.com/2011/07/12/historic-variations-in-sea-levels-part-1-from-the-holocene-to-romans/
Kermit:
I think you will find that the current rate of rise is dropping to 0. This is not the point. The point is that there is sufficient water in the glaciers that the current phase of global warming have not melted, to raise the sea level more than 100 meters. Given that these glaciers did not melt the previous 5 periods of global warming, I am skeptical that they will melt this time either.
Cheers
JE
Joel,
Thank you for demonstrating the alarmist clap trap AGW faith depends on.
SLR is not going to be in meters, much less tens of meters range.
Think of your shoe. Stand it heel down, toe up. Maybe put one shoe heel on top of the toe of the one pointing up. Somewhere between the floor and the toe of the second shoe is our risk.
Unless you are Sideshow Bob, of course.
I was responding to the statement “It is obvious that Earth has seen much higher rates of CO2 with no catastrophic effects,” i.e., what has happened in the Earth’s history. It is really ridiculous to see people who apparent think it would be just fine and dandy to relive some of the events that have happened over the earth’s geological history!
How high the sea level changes are likely to get under the current scenarios is another topic…although it is one where you have to recognize that the rise by 2100 is likely to be just the tip-of-the-iceberg.
Joel,
If you ‘recognize’ that the slr in 2100 is the tip of the iceberg, get your eyes checked.
But now you are recanting the statement you made that we would see tens of meters by 2100?
hunter: Most of the sea level rise is indeed expected to occur over a fairly large period of time, although there are currently arguments going on in the cryosphere community over how fast the land ice might break up.
Since I didn’t make that statement that you claimed that I made, there is no need to recant it. I already clarified what statement I was making, although I also think it was fairly obvious from the context of the comment that I was responding to.
Joel “I suppose that terrorists flying planes into buildings wouldn’t even register. So clearly, all the money we are wasting on fighting terrorism is silly…After all, the Earth has seen terrorists fly planes into buildings with no catastrophic effects”. You’re quite right Joel, “all the money we are wasting on fighting terrorism is silly”, it’s just that the “oxygen of publicity” frightens a credulous public.
Joel, I believe you are mixing actual threat (terrorism) with a non problem issue (global warming).
It is the Precautionary Principle gone mad.
In fighting terrorism we try to keep our way of life and belief , with all these Carbon Taxes we actually destroy it.
Mr. Joel Shore,
Terrorists ‘hate our freedom’… George W. Bush
(what freedom?) TSA, HSA, NSA, ICE, ATF, PATRIOTACT, Predator drones, tasers…
We need to ‘save the world from the ‘unwashed’, with more death & taxes placed upon families around the world… futerra.uk
(In ss-O many words)
How are these two lies any different?
The Bible or An Inconvenient Truth. You must Choose between them.
You will have from now, until 2035, when glacier water will cover the face of the Earth and mankind will all be dead. This may be true, science says…
What is to be, our take-away? We will all need to know these things, just to make informed decisions about our planets safety.
Oh yeah Joel, how much time did it take for Bldg. 7, to hit the ground on 9/11? You can watch the event and time it yourself. Any problems or questions about this terrorist act? I still can’t explain it. No one even flew a plane into this building and it still collapsed into its own footprint. What other examples can you direct me to so that I can see another steel structured building do the same thing after a small fire. We need to work together, be Gung-Ho! Time is essential in coming to a firm understanding of all these events. Another dragon to slay, it seems.
Joel,…
Have you, ever wondered why the elephants paint their toenails red?
It is so they can hide in the cherry trees.
Have you ever seen an elephant, in a cherry tree?
See how good; it has worked?
Okatsune
Tom,
why do you guys have so many myths??? Building 7 had major structural damage from steel and chunks of one of the towers ripping off part of the face. Fires were burning even before the twin towers collapsed from jet fuel and debris raining on it. The Truthers use the testimony of one of the workers who showed up late to try and make their conspiracy case. His statement, parphrased includes, I looked out the window to the right and saw smoke and flames, I looked to the left (where the bulk of the building should have been) and there was no building there. So much for another Truther conspiracy!!!
Porat (quoting me)” “You’ll get nowhere attacking what skeptics say, you have to address what they’re thinking…”
Oh yes, why argue with facts when you can attack the person presenting them…
It’s fascinating how people will take what you say and claim you said the exact opposite. I said you’ll get nowhere by attacking the person presenting the facts, and Eyal responds, if I understand him, with the implication that I said the opposite.
If he was referring to the second half of what I said, I would say that anyone who thinks “address” means “attack” is not cut out to be a diplomat.
Eyal, you’ll get nowhere attacking people with inflammatory rants accusing them of arrogance. By all means claim that CO2 is harmless, this after all is what this blog is about, but lacing it with vitriol does not strengthen your claim.
“Curiously, the surface of the Earth receives nearly twice as much energy from the atmosphere as it does from the Sun.”
Its the chicken and the egg all over again. If the Earth wasn’t warmer the sky would not be warmer. That is my issue with down welling radiation as a tool to explain the greenhouse effect. A warmer atmosphere retains more heat at the surface. The surface temperature is somewhat in balance because of the composition of the atmosphere and CO2 contributes about 5% to the overall effect. So “receives nearly twice…” is not as convincing as loses nearly half.
1.Using an IR thermometer this way can give very misleading results. They are not normally calibrated for low temperatures. The altitude that they are reading will depend on what wavelengths they read at and the atmospheric transparency at that wavelength.
2.”back radiation” is as poor and ill defined as “greenhouse effect” when applied to the atmosphere. Miskolczi wrote a paper using HARTCODE and radiosonde data defining the temperature profile and radiative transfer in the atmosphere. The important concept is optical depth at various wavelengths. At CO2 wavelengths the atmosphere is opaque until you get to high altitudes. The change in CO2 ends up making no significant difference in the heat loss to space.
Al, I am pretty sure I know what you mean by “CO2 wavelengths”… CO2 absorbs some wavelengths very strongly, and others not very much at all; so I presume you mean those wavelengths which CO2 absorbs. (Correct me if I misunderstand you.)
However, note that there is a continuous variation. One of the major reasons CO2 makes a significant difference as you keep increasing it anywhere along the range from 10 ppm to 100,000 ppm is that the atmosphere as a whole becomes opaque to more and more wavelengths. For example, let us say the atmosphere is “mostly transparent” at those wavelengths where 50% or more of that wavelength gets through, and “mostly opaque” at wavelengths where 50% or more is absorbed. As concentrations of CO2 increase, more and more wavelengths move from being mostly transparent to mostly opaque; this is called absorption in the “wings” or “shoulder” of the main absorption band.
Hence the concept of optical depth is indeed crucial, as you say. However, your concluding inference is back to front. It is the continuous relationship between optical depth and wavelengths which means that you do get a significant and continuous change in the loss of heat from the surface into space (very close to a logarithmic relationship) as CO2 concentrations range over values anything from 10 to 100000 ppm. What we could plausibly see on Earth is all well inside that range.
BTW. The atmosphere heats the surface in the same sense exactly that a blanket heats a sleeper. (Though the physical mechanism is a bit different.) As Vaughan points out, the net heat flows are from the surface to the atmosphere; the surface heats the atmosphere, and the atmosphere cools the Earth. So too, look at the heat flows and you see that a blanket doesn’t heat you; YOU heat the blanket.
You are warmer with the blanket than without, and so in normal speech we do say that a blanket is warmer than a sheet, or than nothing at all. Objections to this usage may be pedantically correct; but I’m still going to speak of “sunrise” for the Earth turning towards the Sun, of being warmed by a wool blanket, and of being warmed by the atmosphere.
“in the same sense exactly that a blanket heats a sleeper”. Did you mean to say exactly? It’s the metabolism of the human body heats a sleeper. Blankets don’t heat corpses.
Sorry. Reading on you admit this. However, pedantically correct objections are essential for clear thinking.
“I’m still going to speak of … being warmed by the atmosphere”. But that’s just the sort of loose expression that confuses. The atmosphere doesn’t warm us; it prevents us from cooling more than we otherwise would have done. The term “back radiation” is just an accounting device; something that doesn’t exist at the macroscopic level at all.
Simon,
You are not incorrect when you say “it prevents us from cooling more than we otherwise would have done” but I have found that such statements tend to be misinterpreted by some. I.e., they say, “So greenhouse gases can just slow cooling a little bit; they can’t cause warming.” The reason that this is incorrect is that the temperature of the earth’s surface is determined by the balance between what it receives from the sun and what it emits back into space. So, indeed, slowing cooling can warm the Earth in the sense of increasing the average temperature. I think that you understand this but some of your compatriots do not.
The blanket analogy works, and it is important to realize that it keeps you warm without the blanket having to be as warm as the human body.
Nonsense. The human body keeps the human body warm, not the blanket.
You don’t think a blanket is warmer than no blanket?
Likewise the sun keeps the surface warm, not the atmosphere, but the atmosphere (like the blanket) helps.
“You don’t think a blanket is warmer than no blanket?” No, not for a corpse (or anything else without an internal heat source). Just as cold come sunrise.
Your second sentence is OK. Just don’t confuse the issue by introducing analogies involving us warm-blooded creatures.
The analogy was with the solar-warmed earth. I think it holds.
Simon, I agree with you on the points you made in response to my comment on warming with blankets, and am glad to confirm that.
When I am speaking for myself, I prefer to be as accurate as possible without being confusing or technical. Hence, I would much rather say that the atmosphere keeps the Earth warm; not that the atmosphere warms the Earth. It’s a subtle difference which would be lost on very non-technical folks, and I don’t think it is important to explain the difference UNLESS and UNTIL it has become germane.
In the meantime, I am not going to fuss with other people who speak of the blanket warming them, or the atmosphere warming them, even though this is technically inaccurate as a comment on where heat is flowing. I made this point as a response to this paragraph by Vaughan:
>>> Experienced meteorology professor Alistair Fraser says the atmosphere warms the surface. I, an amateur hack in this area with no meteorological credentials at all, say the surface warms the atmosphere, and moreover at an average power density of 66 W/m2 and sometimes hitting upwards of 200 W/m2. Who’s to be believed? <<<
The answer, I suspect, is that it is not about who to "believe", but about comprehending what someone means. Fraser might be more accurate to say that the "atmosphere keeps the surface warm", but it's not a big deal in most cases. Certainly adding an atmosphere to a planet will make it much warmer, a bit like adding a blanket makes you warmer in bed. I suspect he's just using simple language to convey a simple point.
I'm not insisting this is good usage; but rather suggesting this is probably a case for understanding what someone means rather than deciding not to believe them.
Chris, thanks for your reply. Please help me to understand, if GHGs radiate isotropically, so that any “back radiation” is balanced by an equal and opposite “upward (out to space) radiation”, how it can be legitimate to refer to “back radiation” in calculations as if it had a separate, independent existence.
Back radiation refers to the radiation coming to the surface from the atmosphere. It’s a real measurable flux, and the first direct measurements (confirming theoretical expectations) were in 1954. See Stern, S.C., and F. Schwartzmann, 1954: An Infrared Detector For Measurement Of The Back Radiation From The Sky. J. Atmos. Sci., 11, 121–129..
Since the atmosphere has thickness, you don’t actually have equal upwards and downwards radiation for the whole atmosphere. The top of the atmosphere is cooler than the bottom, and so the radiation at the top is much less than at the bottom.
At any given fixed level, you can speak of a fixed emission, which is equally up and equally down. But that emission level is less as you go up into cooler levels.
It’s easy enough to give the full calculation, but the simple intuition is this. At a fixed altitude you have isotropic radiation. But at different altitudes the radiation is different. So the radiation up out the top is less than the radiation down out the bottom. Of course, the whole thing is driven mostly by radiation coming up from the surface, plus the 100 W/m^2 or so from non-radiant heat flows. The net flow of heat continues to be up from the surface through the atmosphere and out into space, as required by thermodynamics.
Thanks Chris; I’ll think about that. But when you say “Back radiation refers to the radiation coming to the surface from the atmosphere. It’s a real measurable flux” I feel there should be an equal and opposite (and potentially measurable) flux from atmosphere to space which traced back is really a loss of radiation from the surface where it originated. (I need to think about this some more to see it correctly).
Try this thought experiment. (Much simpler than the real atmosphere, but at least it can help show why you don’t have the flux at the top equal and opposite to the flux at the bottom.)
Take a surface receiving 240 W/m^2 of radiant energy (in visible wavelengths, from the Sun). Place above that surface a stack of “n” layers, each of which is transparent to visible light but absorbs a fraction “p” of infrared passing through. Each layer also radiates all the energy it receives, equally up and down. For simplicity, there’s no other way heat flows in this example, other than radiation.
By conservation of energy you have 240 W/m^2 escaping out the top layer. There’s radiation A coming up from the layer below. A.p of that is absorbed into the top layer, and re-radiated, half up and half down. A,(1-p) is simply transmitted through the top layer.
Hence 240 = A.(1-p) + A.p/2 = A(1 – p/2).
If p is 0.1, then 240 = A.0.95 and A = 240/0.95 = 252.63
That is, there is 12.63 W/m^2 going back down from the top layer to the second top layer, and 252.63 W/m^2 going up from the second top layer to the top layer, and 240 W/m^2 going up from the top layer out into space.
You can extend down through the lower and lower layers, and if you presume EACH INDIVIDUAL LAYER radiates the energy it absorbs equally up and down, you end up with the top layer radiating much less than the bottom layer.
If you double n and half p you are in effect breaking each layer into two. Proceed to the limit, and you have a continuous atmosphere, cooler at the top and warmer at the bottom, with the backradiation out the very bottom layer being more than the atmospheric radiation out the top.
A real atmospheric model has to deal with a lot of additional issues, such as non radiant heat flows. (Easier to manage than you might think, as long as you know the atmospheric lapse rate.) But the bottom line is, you do get differing amount of emission at different altitudes, and the backradiation out the bottom therefore does not have to balance with the outward radiation from the top. The balance, or isotropic emission is assumed at each level, or for each molecule. This does not lead to isotropic emission when comparing different altitudes.
For people who really want to follow this, nothing beats trying to work through a standard textbook. It may take months to learn the details this way (based on my own experience of using this method) but the end result is very helpful.
Thanks al for ref to Miskolczi
See Miskolczi’s publications
Especially the most recent presentations:
Poster presentation at the European Geosciences Union General Assembly, Vienna, 7 April 2011 by Miklos Zagoni.
e.g. See Slides 8 and 10 of 20. The downward long wave emission from the atmosphere is shown as Ed compared to the short wave transmitted radiance St.
See definitions in his Summary
See Slides 8 and 10 of 20.
The downward long wave emission from the atmosphere is shown as Ed compared to the short wave transmitted radiance St and the Surface Upwelling radiation Su. Ed can be measured as a function of wavelength.
See also Presentation at the Hungarian Academy of Sciences, Budapest, 17 January 2011
See Science of Doom for why this is (in SOD’s words) just equation soufflé.
Eli Rabett
Other than an ad hominem attack, are there any specific errors in Miskolczi’s models or calculations that your can identify?
i.e. I referred to Ed and Su. Miskolczi also calculated the total IR optical depth.
1) Line By Line Code:
Miskolczi has posted his original HARTCODE code. See:
F.M. Miskolczi et al.: High-resolution atmospheric radiance-transmittance code (HARTCODE). In: Meteorology and Environmental Sciences Proc. of the Course on Physical Climatology and Meteorology for Environmental Application. World Scientific Publishing Co. Inc., Singapore, 1990.
(He has improved the accuracy since then)
Have you found any errors in his code?
2) Optical Thickness definition:
Can you show any theoretical error in Miskolczi’s definition of “TRUE INFRARED FLUX OPTICAL THICKNESS” See slide 6 of 20 which he calls “Tau”?
3) Quantitative evaluation
Then Miskolczi quantitatively models the atmosphere with 250 layers, each location with 9 “streams” (3D directions), using 11 molecular species, each of which is calculated over 3490 spectral intervals.
Have you shown any substantial quantitative error over his choice of quantitative intervals?
4) Historic Data
Miskolczi used NOAA’s TIGR2 which has the longest 61 year data.
See (A. Chedin and N. Scott 1983).
I understand the primary challenges are over the variation in water content over time between the different data sets.
In Slide 17/20, Miskloczi calculates the total IR optical thickness for six sub intervals as well as the total 61 year period. That makes little difference.
When someone calculates Miskolczi’s True IR Flux Optical Thickness for each of the data sets then we can see what the quantitative impact of those variations are.
The other objections appear to be over Miskolczi’s subsequent simplifications and theoretical models.
So can you rise to any quantitative substantive comment to Ed, Su or Tau?
David, I am hoping for a clearer explanation from Miskolczi et al. regarding their argument, Christopher Game tells me such an explanation is in the works. Until then, I suspect that we aren’t going to get very far in discussing their argument.
Judy – When I last looked, Miskolczi’s conclusions required atmospheric water vapor to decline as a compensatory mechanism opposing CO2 increases. At one time, there was some slight evidence for this in the NCEP/NCAR reanalysis data, but this has now been shown to be wrong. Humidity is rising at all tropospheric altitudes, and the principal remaining question is whether it rises fast enough with temperature to maintain high tropospheric relative humidity at a near constant level or whether RH declines even as specific humidity is rising.
Unless there is some new twist to this, I don’t see Miskolczi as worth discussing.
Fred Moolten
I linked to Miskolczi’s presentation because he quantitatively calculates as a function of frequency the Downward Longwave Radiation (DLR) (his “Ed”) that was being discussed. He further calculates the global optical depth. Even if you don’t agree with his resulting stationary model, his evidence of empirical relations between the various upward and downward paramaters is insightful. See his “Empirical Facts” in slide 10 of 20. That data for calculated parameters is based on the observed NOAA data for the respective period. That should be understandable, regardless the long term trends.
On humidity vs time, do you have any good quatitative reviews of the evidence and the uncertainties involved?
WIth temperature trends leveling off since 2000, has humidity continued to rise or not this last decade?
David – Here are a few links on rising atmospheric water vapor as a function of temperature. Some of the old reanalysis data utilized only radiosondes, while more recent studies have included satellite observations. Of the reanalysis studies, only one of five (NCEP/NCAR) showed declining trends, while the others showed rising humidity – see Dessler and Davis 2010. Although not discussed in that reference, the NCEP/NCAR data are characterized not by a smoothly declining curve but rather by downward jumps following instrumentation changes. The latter entailed substituting instruments with slow on/off times with faster-responding instruments. This reduced contamination of water measurements at one altitude by water at different altitudes, and this is thought to explain the jumps.
The recent data entail satellite observations. The two most salient studies were those of Minschwaner and Dessler 2004 and Soden et al 2005. Both reported rising specific humidity (water vapor concentration as a fraction of total molecular concentration), but the former found the humidity response to be shallower than the temperature change, implying that relative humidity (RH) did not keep pace with specific humidity. The Soden et al paper estimated a constant RH as a function of temperature. Both studies are subject to quantitative uncertainties, but it appears that the direction of water vapor change is to increase with rising temperatures, inconsistent with the requirements for the Miskolczi conclusions to be validated. It is also in line with all expectations of what happens to water vapor when the climate warms, but the fact that these expectations are confirmed by observations is important.
Here is the correct Minschwaner and Dessler link.
Thanks Fred for the humidity references.
May I recommend:
Prediction of the Standard Atmosphere Profiles of Temperature, Pressure, and Density with Height for the Lower Atmosphere by Solution of the (S-S) Integral Equations of Transfer and Evaluation of the Potential for Profile Perturbation by Combustion Emissions Robert H. Essenhigh* Energy & Fuels 2006, 20, 1057-1067
http://pubs.acs.org/doi/abs/10.1021/ef050276y
That is the most thorough thermodynamic model of the lapse rate I have seen, including water and CO2 absorption.
Fred
There appear to be other major errors in the ERA reanalysis. See:
Indictment Of The ERA-40 Reanalysis In A New Paper “Erroneous Arctic Temperature Trends in the ERA-40 Reanalysis: A Closer Look” By Screen and Simmonds 2011 which extracts key sections of:
Screen, James A., Ian Simmonds, 2011: Erroneous Arctic Temperature Trends in the ERA-40 Reanalysis: A Closer Look. J. Climate, 24, 2620–2627. doi: 10.1175/2010JCLI4054.1.
As temperature rise is overestimated, I expect that the humidity rise is also overestimated.
So a lot of climate models will likely have to be “retuned”.
It will be interesting to see how corrected models and miskolczi fare on the same data.
David – I’m familiar with reanalysis issues. I think Miskolczi is a lost cause, because we now have compelling evidence from multiple sources, including satellites, that atmospheric water increases at all tropospheric altitudes as the climate warms. Other errors in his analysis have been identified by other participants here, but given the humidity data, his conclusions become largely unsupportable from that information alone.
My interpretation of Miskolczi is as follows. It all comes down to his definition of optical depth which is actually very special. It comes from the amount of IR leaving the top of the atmosphere that originated directly from the surface. That is, it is dominated by the window photons, perhaps with a small contribution from side-bands. So he takes this top radiation and divides by the total leaving the surface, and from these two numbers derives his optical depth. Not surprisingly, since he only looks at window photons, CO2 and H2O emission have little effect on his defined optical depth. So his statement that his optical depth may not have changed may be correct, but says nothing about emitted radiation from the atmosphere, which is where the signal should be.
Jim D
Re “is dominated by the window photons, perhaps with a small contribution from side-bands . . .his optical depth may not have changed may be correct, but says nothing about emitted radiation.”
Please go back, reread and try to understand both Miskolczi’s definition and method of calculation, and his results.
He calculates the emission across ALL 3490 spectral frequencies with the latest evidence for ALL GHG, not just CO2 and H2O (not just for the “window” photons). This is across 250 levels using an average atmospheric lapse rate calculated from the TIGR2 data weighted across the globe for each of the 61 years. (I think this average TIGR2 lapse includes the effect of clouds on atmospheric temperature.)
This global optical depth is directly linked to the “emitted radiation” including “the signal”.
You have to look at how he defines S_T. It is very specifically the part of the IR out of the top that can be traced to the surface. This is all he used in his optical depth.
David,
I think that Miskolczi’s and Claes Johnson’s work are similar in the respect that the math looks correct to me. Tomas may disagree with that statement based on his own perusing of Dr. Johnson’s work, but it looks right to me.
What is also similar is that when faced with criticism about the theoretical underpinnings of their work (the real physics the math implies) they point to the math or computer code from which their numerical analysis comes from. They say ‘show me where the math is wrong’. To which I would ‘it’s not wrong’.
But the physics they are implying with correct math is wrong.
Specifically, for Miskolczi’s work the atmosphere has to ‘know’ where water molecules are and how many water molecules there are in order to condense the right number of them to maintain a specific value of the optical depth in the IR. But because he has come to this problem from observations, he has no physical mechanism in analytical mathematical form from which we could decipher such a mechanism.
More than that, to a molecular spectroscopist like myself, it’s hard to believe because why wouldn’t the samples in my lab do the same thing? Why would it only happen in the IR region? Would the same phenomena happen if earthlight were spectrally centered in the UV such that we were discussing electronic transitions versus vibrational transitions?
The conclusions he’s made based on his analysis of observational data are much too strong in my opinion. Without a serious accounting for the physical process that ‘entangles’ disconnected GHG molecules and the light passing through the atmosphere, it doesn’t matter if his math or code are correct. The physics itself simply doesn’t add up to form a coherent picture with what we already know to be true.
I think Roy Spencer did a good job of discussing Miskolczi’s work and, I think, even admitted that he wanted it to be right. But it doesn’t add up.
Maxwell, the role of math in science is something I study. If the math is correct but the physical results are incorrect then at least one of the initial (that is, not derived) physically interpreted mathematical expressions must be physically false. You need to find that one.
David,
You’re looking at the situation in reverse. Miskolczi isn’t deriving mathematical equations to determine how atmosphere works physically. He is fitting a theoretical framework to a specific set of observational data that, he thinks, show that water content of specific columns of air are constant over time. From there he argues this means the atmosphere ‘wants’ to maintain a specific magnitude for the greenhouse effect (IR depth) and so adding CO2 to the atmosphere just condenses water.
So there are no ‘initial physically interpreted mathematical expressions’. It’s really just data fitting.
But even if there were equations, as in the case of Dr. Johnson’s work, I know that if I take a container of water vapor and CO2, water is not going to condense upon my adding more CO2. Dalton’s law of partial pressures tells us that the vapor pressure of water will only change by adding more water. Not more CO2.
There is no evidence in the spectroscopy literature that anything even closely resembling what Miskolczi concludes to true plays a role in the absorption of light in any frequency region. So I’m not going to waste my time, and I would advise others not to waste their time, looking for ‘initial physically interpreted mathematical expressions’. They’re somewhere and it doesn’t really matter where.
Maxwell
Re “to a specific set of observational data that, he thinks, show that water content of specific columns of air are constant over time.”
I think you misunderstand Miskolczi’s method. He takes the actual observed varying TIGR2 humidity and CO2 etc over time and calculates the consequent optical depth from that. The objections are whether the observed decline in humidity in the TIGR2 with rising CO2 is real or not. Miskolczi’s method just calculates the global optical depth from whatever the available GHG’s including humidity and CO2. From the data he used, that appears to be stable.
Regarding the rest of his model, he applies an entropy production optimization which results in the stable global optical depth.
Even with other data sets, I would not be surprised if the Planck weighted global optical depth does not vary strongly. E.g., during the last decade when the global temperature has not warmed as projected by IPCC.
There are numerous methods besides condensation for the atmosphere remaining stable. See Willis Eschenbach It’s Not About Feedback
Whatever the GHG concentrations, we still need an accurate Planck weighted calculation of the optical depth. Miskolczi if the first to provide a quantitative Line By Line calculation with available long term data that I am aware of.
David H,
I think you’re right. He’s looking at constant IR optical depth, not humidity.
Thanks for making that point clearer.
In either case, however, Miskolczi is not deriving first principles physical law and then looking to substantiate it. It finds ‘curious’ data and then tries to fit that data to a particular physical model. So there are still no ‘initial physically interpreted mathematical expressions’.
Cheers.
maxwell
Re: “You’re looking at the situation in reverse.”
I think you are from your comments.
Please go back and see the progression.
Miskolczi has identified 7 major empirical relations between IR parameters in the atmosphere based on that TIGR evidence. He also calculates the optical depth from that original evidence.
From thse empirical observations and correlations, he develops his consequent relationships from which he infers a stable atmosphere and stable optical depth. He then measured the optical depth from the reanalysis data over 61 years. That shows a stable total optical depth.
The optical depth method can equally be applied to any atmospheric data.
David – Even the math is wrong. Work your way through Appendix B of Miskolczi (2007) and find the error(s). They count; they nullify his claim to have found a revision of the classical Milne gray atmosphere result.
Pat – Please provide a link or publication to where those errors have been identified and preferably corrected. Do those corrections better address the surface step jump in ground vs air temperature?
See my post above Do any of those changes affect his calculation of the global optical depth? Or of his method of averaging the TIGR2 data?
If not, any differences over that other portion of his model should NOT make any impact on these calculations of either the global optical depth or the Downwelling Longwave Radiation (DLR) (or Ed) that we were addressing here.
It may have been suggested before, but, a possible mechanism would be that increased CO2 actually displaces water moisture in the parcel. That is the air can only hold so much and the CO2 interferes with the ability to hold the water vapor. No I do not have any idea if this is physical. Should be possible to disprove experimentally if it hasn’t been already.
kuhnkat.
“It may have been suggested before, but, a possible mechanism would be that increased CO2 actually displaces water moisture in the parcel.”
With all due respect, water ‘condensate’ absorbs CO2 at an alarming rate (CO2 is the first Earthly gas to diffuse into pure water) and if there isn’t a disparity of low CO2 in the strat compared to higher levels in the lower tropo I’ll be surprised (theoretical assumption based on standard physics and ‘diffusion pumps’). :)
I’d need a ‘precedent’ scenario to swallow this because I can’t envisage how CO2 can ‘precipitate’ water from Earth’s atmosphere. However, I’m open to the suggestion that CO2 ‘ionises’ “water moisture” in Earth’s atmosphere and alters its PH. Perhaps this could be a ‘clue’?
If not, Archimedes may come to the rescue when all players are in a ‘gaseous state’ within the ‘parcel’. CO2 is heavy and WV is light. It’s possible that CO2 weights the overall parcel to lower altitudes where WV can be absorbed into existing “water moisture” (water droplets).
It’s a ‘minefield’! :)
Best regards, Ray Dart.
Thanks Ray,
you probably heard my arms flapping!!
I found it an interesting idea. It would displace water vapor if anything and based on the actual amount of CO2 added couldn’t be a large effect. It was interesting based on it being counterintuitive that water vapor is NOT increasing noticeably in a warming world. Of course, there is the issue that we may NOT be warming or not much, and only poor measurements and adjustments say we are.
My vague idea was also electrostatic. The weight based I was considering more on the idea that under a certain set of temperature/pressure conditions there would be an upper limit on the mass that could exist in a parcel. Basically our CO2 emissions filling up really small holes!! See what fun it is to be ignorant? 8>)
I hadn’t considered your ionization scenario. That also sounds interesting.
Follow the link. SoD looks at the equations that Miskolczi presents as well as the data for optical depth and the calculations. This had previously been done in detail by Nick Stokes who came to the same conclusions. As Fred points out, the data that Miskolczi used were cherry picked.
Eli
“the data that Miskolczi used were cherry picked.”
Miskolczi used NOAA’s TIGR2 which has the longest available record of the major atmospheric GHGs – H2O and CO2. THat is not “cherry picking” but using the longest available record.
There are now questions on the accuracy of that humidity data, as well as of recent ERA temperatures.
We both need an accurate way to calculate Ed and the optical depth. Miskolczi is the first to provide that Planck weighted global IR optical depth that I am aware of. That can then be applied to other data sets.
I expect the impact will be that the optical depth does not vary much and that the major variations will be in albedo from cloud variations and transport mechanisms – wind and latent heat.
e.g. see Willis Eschenbach
Keep on “kicking the tires” to see what is true.
Reply to David L. Hagen at | August 14, 2011 at 9:15 am |
David – Haven’t we discussed this before?
Sorry, I don’t have a link handy, but you can easily work the math out for yourself. Briefly, Miskolczi’s ‘solution’ (eqn B-11) violates the assumptions under which it was derived, fails to satisfy the upper boundary condition (zero downward LWR at tau = 0), and implies that the function Bo has no maximum in tau. This last point nullifies his claim that there is a particular optical depth that maximizes the energy transport (yes, that optical depth which he claims matches the observational results to three(!) significant figures). So there is no valid revision of the Milne solution under Miskolczi’s hypothesis, and no theoretical basis for the idea that the atmosphere is self-regulated by optical depth adjustments.
Regarding the calculation of Ed and a gray atmosphere optical depth, it is clear that these quantities depend on atmospheric structure, which varies with GHG content, etc., and so have no ‘universal’ values, despite Miskolczi’s attempt to justify such.
All this and more was hashed out a couple of years ago at David Stockwell’s website and elsewhere. It’s not worth revisiting; there is virtually nothing valid in Miskolczi (2007) beyond eqns (1) and (2).
TIGR 2 has a well known dry bias in the troposphere. TIGR 3 is much more representative and larger and TIGR 2000 is even better. He picked the cherries
David Hagen: Eli Rabett: Other than an ad hominem attack, are there any specific errors in Miskolczi’s models or calculations that your can identify?
The one that really caught my attention is that after laborious calculations that entailed splitting the atmosphere into 2000 layers, Miskolczi computed the total kinetic energy of Earth’s atmosphere at 1/5 of its correct value. From this he obtained that the potential energy of the atmosphere (which he did compute correctly) was twice its kinetic energy when it’s easy to see from the constant-pressure specific heat of air that it is 2/5 of it. And it wasn’t an isolated mistake, he’d thought this for several years, including half a year after Viktor Toth had pointed it out to him. Details at
http://judithcurry.com/2010/12/05/confidence-in-radiative-transfer-models/#comment-20196
Vaughan Pratt
Re:
Sadly it appears that you misread/misunderstood Miskolczi, and presumed that he calculated the “TOTAL kinetic energy” – rather than read what he actually calculated:
(Only ONE degree of freedom, NOT the total kinetic energy of a diatomic gas with 5 degrees of freedom) See Slide 21/24 of Presentation at the Hungarian Academy of Sciences, Budapest, 17 January 2011 http://miskolczi.webs.com/academy.pdf
He then shows that the “Gravitational potential energy” Omega is two times the SINGLE degree of “kinetic energy” (or internal energy).
I encourage you to review and compare Toth (2010) Pacheco (2003) and Miskolczi (2011) slides 21, 22. I understand that they agree with each other with a bit of algebra between the two methods of presentation.
On the 1/5th factor, by the equipartition theorem for a diatomic gas, there are three translational degrees of freedom for a gas molecule (XYZ), and two rotational modes for a diatomic gas (~ air as mostly N2+O2) for a total of 5 degrees of freedom (DOF). However, only the vertical translational Degree of Freedom Kz of the internal thermal energy is involved in the virial theorem. Thus Miskolczi calculates ONLY the ONE Vertical degree of freedom when calculating the vertical component Kz of the thermal energy – thus Miskolczi’s calculation of the vertical degree of freedom as 1/5th of Toth’s total “kinetic energy” (or Pacheco’s internal energy U). Then Miskolczi shows that the total gravitational potential energy Omega is twice the single vertical component of the kinetic or internal (thermal) energy T (equal to one fifth the total kinetic energy ). This gives Toth’s equation (25) of 2/5 = U (or Pacheco’s U/P = ev/R = 5/2).
Re: “he’d thought this for several years, including half a year after Viktor Toth had pointed it out to him”, I think you slander him without evidence. Toth and Miskolczi were discussing this issue with colleagues in April 2010 after Toth paper mid March 2010. They agreed that they arrived at algebraically equivalent statements on the virial calculation, and the degrees of freedom.
Sadly it appears that you misread/misunderstood Miskolczi, and presumed that he calculated the “TOTAL kinetic energy” – rather than read what he actually calculated:
This raises a number of interesting questions, David.
1. How come you’re just pointing this out now when neither you nor Miskolczi had this response to my December post? You had several responses none of which mentioned this possibility.
2. Energy is not a vector but a scalar. What does “vertical component of energy” mean?
3. Miskolczi’s journal paper assumes energy is conserved. How can this be true if he’s only working with 1/5 of the kinetic energy of the atmosphere? Conservation only holds for the TOTAL kinetic energy plus potential energy.
4. Why is there no discussion in his journal paper of this idea that energy is a vector with components that you can take one of? Introducing nonstandard concepts like that is a sure-fire way of sneaking fallacies into a paper.
5. What’s with this “sadly” stuff? You’re always the one sanctimoniously holding us to a professional standard of discourse. Your “sadly” drags you down to my street-fighter level, for which I make no apologies. (I apologize for any apologies I may have made inadvertently—I know for sure I haven’t apologized exactly once.)
And thanks to you for your comments below. They track well with my thinking. I am on a dial-up connect (slow) and have way too many other things to do to even get this blog read.
This may be of interest.
http://ruby.fgcu.edu/courses/twimberley/EnviroPhilo/Ferenc.pdf
It gives a more detailed explanation of Miskolczi. I was also hoping Dr. Curry would find the time to read. As per comments on a previous thread, Miskolczi is a bit short on detail. This is one of the better explanations I have found.
Note: comment above in reply to David L. Hagen
“While I seriously doubt whether climate skeptics will thank me for pointing it out, I don’t believe their arguments impress the swing voters in the climate debate as convincingly as they might”.
The swing voter pays little or no attention to either side. We just like to think we’re very influential …
http://thepointman.wordpress.com/2011/08/04/i%e2%80%99m-not-a-scientist-but-%e2%80%a6/
Pointman
Dr. Curry,
Most skeptics I am aware of do not agree with the Greenhouse Dragon.
Using the Dragon as a proxy for ‘what skeptics believe’ is a bit of a straw man.
Spencer, Lindzen, Pielke, Sr. and Salby all have critiques of AGW catastrophism that has nothing to do with the Dragon.
While it is as much fun to attack a fringe like the Dragon, as it is to jump on Gore or Romm or Hansen for their ‘fever’ talk, or spittle flecked spews or tipping points, I do not believe that many in the AGW community actually support such extremist non-science from that side either.
Perhaps it would be more constructive to not kick a dead dragon?
Hunter, the skydragon group is quite difficult to slay, see the previous threads where the dialogue continues unabated. This is one that I would really like to slay, so I keep trying some different things. so this particular dragon isn’t dead yet, but this group is becoming increasingly marginalized IMO.
on the previous thread the recent Postma paper was discussed.
He is loosely associated with the skydragon group.
His Paper ran for 44 pages with detailed calculations.
He even suggested an experiment to test the Greenhouse Theory.
We all believe in experiments, don’t we?
The arguments to counter the paper were very weak or non existent.
The fact that world temperatures have not risen for 15 years while CO2 levels have surely must have some greenhouse advocates scratching their head.
I’ve seen plenty of empirical confirmation of the CO2 theory but I am replying due to your last paragraph. Surely that the fact that the world’s temperatures haven’t risen as fast as the previous years are interesting, but in no way they are sufficient evidence for the basic CO2 mechanism to be doubted.
There just wasn’t enough time for that. However, there were and there are people scratching their heads because their own predictions were quite more catastrophic than the reality.
Actually, the only legitimate debating topic regarding Postma’s paper was whether he was actively deceiving others or severely deluding himself. Personally, I am on the side of actively deceiving, but I admit that this is a legitimate subject of discussion.
That Bryan thinks “the arguments to counter the paper were very weak or non existent” is frankly laughable.
Oh what the hell, let’s have a look at some of the nonsense that Postma has written. Here is one section, regarding the lapse rate:
Here are just a few problems:
(1) He hasn’t justified why the atmosphere is “essentially fixed in depth” or, more importantly, why the part of the atmosphere that we call the troposphere, where the lapse rate is equal to the adiabatic lapse rate, must be fixed in depth. I see no reason why the latter must be true…and in fact it is not expected (or measured) to be true under increasing greenhouse gases.
(2) He pretends that the lapse rate is some condition that is at the adiabatic value in the absence of greenhouse gases but that greenhouse gases would be expected to modify modify from what he has computed. However, that is not how it works. The adiabatic lapse rate is a stability limit. So, whatever heating from below, be it the solar input or the heating from greenhouse gases or what-have-you tries to raise the lapse rate,instability is produced, convection sets in, and the lapse rate is pushed back down to its adiabatic value.
(3) He argues that water vapor lowers, rather than raises the lapse rate (as he has wrongly argued greenhouse gases should do). Apparently, one is supposed to entertain the idea that water vapor has no other properties besides being a greenhouse gas. Water in fact is a condensable gas and so when it condenses it releases a lot of energy…its heat of vaporization…which for water happens to be particularly large. This is why the moist adiabatic lapse rate is lower than the dry one. The evaporation-condensation mechanism is, of course, an important way by which heat is transferred in the atmosphere. Surely, Postma is aware of this fact and yet he omits it.
So, in less than one paragraph of his 44 pages of nonsense, we have identified 3 major errors that render pretty much his entitle argument about the adiabatic lapse rate and its relation to greenhouse gases as nonsense. Exactly how many paragraphs do we have to do this for before people accept that the only use for Postma’s work is for studying how people go about peddling pseudoscientific nonsense?
Joel thinks I have been over dismissive of his claims to have found flaws in Postmas paper.
Are these points significant or “fatal” if correct
Lets see.
“(1) He hasn’t justified why the atmosphere is “essentially fixed in depth” or, more importantly, why the part of the atmosphere that we call the troposphere, where the lapse rate is equal to the adiabatic lapse rate, must be fixed in depth.”
If you read Postmas papers he clearly says the environmental lapse rate (ELR) differs from the DALR mainly because of latent Heat of water effects.
So the average emission level moves up and down accordingly.
All other things being equal what would a 1degree C rise in average surface temperature entail.
(after all there has only been a rise of 0.7C over the last 150years)
Well lets use the ELR
It looks at first that this might increase the mission height by 100/5000 or 2%
However though the linear increase because of temperture suggests 2% the emitting space is related to the volume or a cubic effect.
Its resonable to think that this would reduce the increase to an even smaller figure by back feedback to increase ELR.
I will leave it as an exercise for you to do the same analysis for the DALR
Postma is correct but even if he was not this point is not central to the paper.
“(2) He (pretends!!!!!!!) that the lapse rate is some condition that is at the adiabatic value in the absence of greenhouse gases but that greenhouse gases would be expected to modify modify from what he has computed. However, that is not how it works.”
Note the pretends here!!!
All part of the usual Joel smear tactic.
There seems to be general agreement among a wide range of opinion that radiative transfer has nothing to do with the DALR.
So I don’t know what kind of point Joel is making here.
Incidently Joels personal model predicts an 80K troposphere effect.
What happens to radiative transfer in the troposphere during a day when DALR is followed?
This is one of the inconvenient facts that Joel chooses to ignore.
Further if you look at other threads in this series you will find Joel deeply confused about the DALR.
He reluctantly had to agree that I was correct in an earlier exchange.
Postma is correct but even if he was not this point is not central to the paper.
(3) Joel’s silly point about Postma not knowing about the Latent Heat of Vapourisation of Water I have already dealt with.
So there you have it Joel’s points that he was so excited about proved to be hot air as usual
I think I’ll just leave this as a challenge to other readers here: If you can make any sort of coherent arguments out of the blather from Bryan above, could you kindly do so and let us in on what those arguments are?
Oh what the heck, let’s have a look at some of the nonsense that Postma has written. Here is one section, regarding the lapse rate:
Here are just a few problems:
(1) He hasn’t justified why the atmosphere is “essentially fixed in depth” or, more importantly, why the part of the atmosphere that we call the troposphere, where the lapse rate is equal to the adiabatic lapse rate, must be fixed in depth. I see no reason why the latter must be true…and in fact it is not expected (or measured) to be true under increasing greenhouse gases.
(2) He pretends that the lapse rate is some condition that is at the adiabatic value in the absence of greenhouse gases but that greenhouse gases would be expected to modify modify from what he has computed. However, that is not how it works. The adiabatic lapse rate is a stability limit. So, whatever heating from below, be it the solar input or the heating from greenhouse gases or what-have-you tries to raise the lapse rate,instability is produced, convection sets in, and the lapse rate is pushed back down to its adiabatic value.
(3) He argues that water vapor lowers, rather than raises the lapse rate (as he has wrongly argued greenhouse gases should do). Apparently, one is supposed to entertain the idea that water vapor has no other properties besides being a greenhouse gas. Water in fact is a condensable gas and so when it condenses it releases a lot of energy…its heat of vaporization…which for water happens to be particularly large. This is why the moist adiabatic lapse rate is lower than the dry one. The evaporation-condensation mechanism is, of course, an important way by which heat is transferred in the atmosphere. Surely, Postma is aware of this fact and yet he omits it.
So, in less than one paragraph of his 44 pages of nonsense, we have identified 3 major errors that render pretty much his entitle argument about the adiabatic lapse rate and its relation to greenhouse gases as nonsense. Exactly how many paragraphs do we have to do this for before people accept that the only use for Postma’s work is for studying how people go about peddling pseudoscientific nonsense?
My favorite part is where he finds that 5 km is the altitude for -18 C, which is the radiative equilibrium temperature (255 K), then seems to think it must always be 5 km even without greenhouse gases. Priceless,
I agree Jim. That is probably the single most fundamental error that pervades both of his papers.
Jim D
He does not think that the the ensemble radiation level “must always be 5 km”
Where did you get that silly idea?
I’m surprised at you.
Does he concede that -18 C can occur at the surface when you don’t have GHGs? I don’t see it. He insists on his gravity argument.
Joel says
Surely, Postma is aware of this fact says Joel at the bottem
The answer is yes what makes you think otherwise?
Hence this paragraph could be written by a headless chicken.
(3) He argues that water vapor lowers, rather than raises the lapse rate (as he has wrongly argued greenhouse gases should do). Apparently, one is supposed to entertain the idea that water vapor has no other properties besides being a greenhouse gas. Water in fact is a condensable gas and so when it condenses it releases a lot of energy…its heat of vaporization…which for water happens to be particularly large. This is why the moist adiabatic lapse rate is lower than the dry one. The evaporation-condensation mechanism is, of course, an important way by which heat is transferred in the atmosphere. Surely, Postma is aware of this fact .
Bryan: If he is aware of this and yet he uses the fact that the lapse rate is what it is to support an argument that it doesn’t support, then he is intentionally deceiving people.
Joel
You realy are scraping the bottom of the barrel here.
After deep thought and weighty deliberation youhave identified a fatal error in Postmas paper.
Perhaps he does not know about the Latent Heat of Vapourisation and its effect on the lapse rate.
Certain things are taken for granted at this level.
Every high school physics pupil knows about Latent Heat.
He has not mentioned Newtons second law perhaps this is the next fatal flaw you will find.
Of much more interest to readers would be an explanation of how radiation alters the lapse rate.
That was a point made by Jim D and yourself but neither of you gave an example where it was fully accounted for
Bryan,
(1) The point is not that he hasn’t mentioned the explanation of a certain phenomenon but that he has used the phenomenon to imply that it tells us something about the greenhouse effect when it does not.
(2) Your sentence “Of much more interest to readers would be an explanation of how radiation alters the lapse rate” shows that you have either failed to read what I have written or you are engaged in active deception. Which is it? [Hint: We are not saying it alters the lapse rate over the troposphere, where it is limited by convection, but it can and will alter where the tropopause is and it will alter where the effective radiating level is.]
I think that everyone should look at your response here to understand how peddlers of pseudoscience like yourself operate and why you can write nonsense about how we haven’t found any major errors in G&T and Postma. We identify them and you ignore them. For any thoughtful person, your responses here are doing your cause more harm than good by illustrating in black-and-white how you operate.
Joel
I thought we should revisit your recent model of the atmosphere
http://scienceblogs.com/stoat/upload/2010/05/halpern_etal_2010.pdf
In it you show a 3 layer model of the atmosphere producing a 80K effect all on its own by radiative transfer.(pg 1318,1319)
Now such a model must be considered to be at the pinnacle of research from the Golden Age of the Greenhouse Theory.
Yet the action of the gravitation field on the air as represented by the adiabatic lapse rate(See Postma pg 16) will in itself produce a similar range of temperature given that the Sun directly heats the ground.
This doubling of the expected temperature range to 160K for the troposphere shows that your model has some fatal flaws.
You might argue that even more slabs or layers are required.
You said that more layers would produce an even better result.
If we have a very large number of slabs then the ” f ” factor will tend to 2 .
See Postma 12 and 13.
This results in the ground temperature being independent of the Sun.
I find it hard to comprehend that such a fantasy model was ever seriously considered.
The model you are describing today is nothing like your model from 2010.
Perhaps you should tell us why you discarded the previous one
Bryan,
So, after a lame attempt at a counterargument to one of the 3 major errors I found in **less than 1 paragraph** of Postma’s paper, it seems you have decided to change the subject from Postma’s nonsense paper. I assume that means you will no longer make the false claim that nobody has shown major errors in Postma’s work?
Your critique of our paper continues the same sort of nonsense your other posts contain.
(1) We say right in the paper that the model is not good for quantitative calculations. The reason that we use it is that we want the simplest possible model that allows us to demonstrate G&T’s misconceptions. Hence the 80 K value should be taken with a grain of salt.
(2) Your claim of this doubling of the temperature difference due to the adiabatic lapse rate is simply nonsense. As we have pointed out to you many times now, the adiabatic lapse rate is only a stability limit on the actual lapse rate. That means that in regions of the atmosphere where the radiative physics wants to impose a larger lapse rate than this (i.e., the part of the atmosphere heated strongly from below), convection occurs and limits the lapse rate to the adiabatic value. But the cause of the large lapse rate is the heating of the atmosphere from below (by both solar radiation and greenhouse gases), not the adiabatic lapse rate (which is why the lapse rate is nowhere near the adiabatic lapse rate in the stratosphere). Your argument is analogous to the following: I drive my car down the Thruway at 65mph, so I cover 65 miles in one hour. However, there are also these signs (called “speed limit signs”) along the side of the road that say 65mph, so that contributes another 65 miles in an hour. Therefore, I must travel a total of 130 miles in an hour.
(1) Postma’s f tending toward 2 is not related to our statement about a large number of slabs. In Postma’s model, it makes no physical sense to set f greater than 1 since it represents an absorptivity, which must be a value between 0 and 1.
(2) We say that “a more realistic model would split the atmosphere into a much larger number of layers for integration and take into account the detailed spectral dependence of absorption and emission, as is done with line-by-line radiation codes.” Note the parts you left out. Also, when you split the atmosphere into more and more layers in this manner, each layer will have a small absorptivity. It is like successive approximations of an integral by dividing the area up into more and morerectangles that have each have a smaller and smaller base.
(3) Even though I have explained how you misread what we said, it is perhaps instructive to look at what would happen if we instead just added more and more BLACKBODY layers to our model (which means we are changing the physics of the situation with each additional layer, rather than converging to a better approximation of the same physics). The answer is indeed that the surface temperature gets larger and larger without bound. Is this realistic? Of course not, and the reason is that the assumption that we have made is that the layers are transparent to solar radiation but perfect absorbers of terrestrial radiation. This approximation is not too unreasonable when the surface temperature is such that the emission spectrum barely overlaps that of the solar spectrum, but it will become a very bad approximation as the surface temperature approaches that of the sun! Kirchhoff’s Law intervenes and prevents us from ever being able to make the surface temperature of the earth hotter than the sun no matter how much greenhouse gases are in the atmosphere.
…whoops … Sorry about the formatting: I screwed up the final tag in that previous post!
Joel Shore says
He has found fatal flaws in the Postma paper.
He thinks Postma has not heard of the Latent Heat of Vapourisation.
……and…. apparently nothing else?
Very impressive.
I said about the paper co-written by Joel
In it you show a 3 layer model of the atmosphere producing a 80K effect all on its own by radiative transfer.(pg 1318,1319)
Yet the action of the gravitation field on the air as represented by the adiabatic lapse rate(See Postma pg 16) will in itself produce a similar range of temperature given that the Sun directly heats the ground.
This doubling of the expected temperature range to 160K for the troposphere shows that your model has some fatal flaws.
Joel says
“(1) We say right in the paper that the model is not good for quantitative calculations. The reason that we use it is that we want the simplest possible model that allows us to demonstrate G&T’s misconceptions. Hence the 80 K value should be taken with a grain of salt.”
I dont take any of it seriously but you have still to say how it fits into the already structured troposphere
Joel says
“(2) Your claim of this doubling of the temperature difference due to the adiabatic lapse rate is simply nonsense. As we have pointed out to you many times now, the adiabatic lapse rate is only a stability limit on the actual lapse rate.”
I say
You have this exactly back to front
The dry adiabatic lapse rate is set by the gravitational field acting on the atmosphere.
Its fundamental and gives the structure around which the environmental lapse rate is formed.
What you have said here is like saying if you jump out of an aeroplane and parachute down you have changed the Gravitational Field Strength.
Very silly.
You said
(1) Postma’s f tending toward 2 is not related to our statement about a large number of slabs. In Postma’s model, it makes no physical sense to set f greater than 1 since it represents an absorptivity, which must be a value between 0 and 1.
Postmas calculation was for Venus (see graph)
You said
(3) Even though I have explained how you misread what we said, it is perhaps instructive to look at what would happen if we instead just added more and more BLACKBODY layers to our model .
I say
Filtered line spectra are not black bodies or even gray bodies
I said
The model you are describing today is nothing like your model from 2010.
You said
I’m not even sure what you mean by “the model you are describing today” as I have not been describing one particular model.
I say
Well when making some incorrect statement about the average emission level I asked what difference would including greenhouse gases make.
You said none it is all at the top of the atmosphere.
But apparently you have backed of this model.
Perhaps you realised it was too close to the model that Postma proposes
Joel you have slip slided any awkward questions but for me the big disappointment was your confusion over the dry adiabatic lapse rate.
Generally physicists have a feel for the underlying structure and forces.
This seems to be absent as far as your concerned.
Its a pity.
Bryan says:
Your mischaracterization of my criticisms of Postma is an outright lie and everyone who looks at my criticisms can see what a liar you actually are.
The rest of your post are more mischaracterizations and evidence that your understanding of the adiabatic lapse rate is essentially non-existent. There is no need for me to continue to respond to such nonsense. You have done a better job showing how dishonest and ignorant you are than I can do by prolonging this nonsense any longer.
Just so people don’t have to wade through all of Bryan’s sophistry to see what I said about the three major errors in just part of one single paragraph of Postma’s “paper”, here is the main part: http://judithcurry.com/2011/08/13/slaying-the-greenhouse-dragon-part-iv/#comment-98524 You can look below that for additional discussion (especially JimD’s post directly below).
Joel Shore reverts to form once he has lost the argument.
For instance he thought he had found fatal flaws in the Postma paper.
He thinks Postma has not heard of the Latent Heat of Vapourisation.
……and…. apparently nothing else of substance?
Very impressive. Judge for yourself !!!!
He also thinks Postma is a liar and of low moral character.
Gross unsubstantiated abuse is pretty much par for the course with Joel.
I have had several exchanges with Joel and they usually end up with him admitting I was right.
Joel thinks Michael Mann is an honest and careful scientist.
He thinks climategate shows only harmless e-mail communication
He is part of an extreme fundamentalist global warming fanatic faction which includes Joshua B. Halpern, Chistopher M. Colose, Chris Ho-Stuart, Arthur P. Smith
They wrote a comment paper together which even Joel now admits contains basic errors in thermodynamics
To say that they are big fans of Judith Currie would indeed not be true.
Joel often gets things wrong but if you correct him, expect gross abuse.
Plenty of abusive attacks mounted by Joel on different posters can be found in these threads.
Bryan,
You are either incapable of understanding Postma’s paper and learning from those who know better, or are actually trying to deceive people who know better. Which is it? It is a continued source of entertainment though.
Thanks, Bryan, for the continuing your tirade of nonsense. I particularly love this part:
So, which is it: Do I admit you are right? Or do I grossly abuse you when I get things wrong and you so graciously correct me?
These are the actual facts: I don’t get things wrong very often. This is not because I am more brilliant than anybody else but simply because I don’t tend to mouth off about things that I don’t understand…and I try to check things before I say them if I am not fairly confident that they are correct. But sometimes, I still make mistakes and when I do, I admit them. For example, here I admitted to kuhnkat that he was right and I was wrong about clouds on Venus reflecting (as opposed to absorbing and emitting) a lot of IR radiation: http://judithcurry.com/2011/01/31/slaying-a-greenhouse-dragon/#comment-97325
I have also admitted that we ended up being somewhat careless in terminology in our use of the word “heat” in our comment on Gerlich and Tscheschner (G&T)…However, I doubt that it would cause any serious confusion with most readers, although it may annoy a few. It makes absolutely positively no difference to our conclusions, since our conceptualization was absolutely correct even if our use of terminology was imperfect. At any rate, I have learned from this mistake and am always careful now to use the term “correctly”. This seems not to be good enough for Bryan, however, who can’t stop harping about it and deceptively tries to make people believe that it in any way impacts our conclusions on the fatal conceptual errors that we pointed out in G&T’s work.
As for abuse: One thing that I am quite intolerant of is people who engage in pseudoscientific tactics like distorting the facts, misrepresenting what others say, and so forth … That is really why Bryan and I don’t get along as he is both a master of these tactics and a defender of others (Postma, G&T, the Slayers) who employ these tactics. If there was a prize for peddling pseudoscience on the internet, I would certainly nominate Bryan with gusto.
[I am also a little intolerant of people who consistently say things with the utmost confidence that are simply incorrect. It is fine to be ignorant about certain things, as all of us are, but to combine that ignorance with a large degree of arrogance…and an unwillingness to learn…is a really toxic combination.]
Joel Shore | August 14, 2011 at 9:09 pm | says
“These are the actual facts: I don’t get things wrong very often.”
just the thermodynamic definition of heat flow, that’s all
So Joel, how come you guys haven’t published a rebuttal to G&T’s published reply to your “comment” or even a letter to the editor of the journal? When a rebuttal is published, but no rebuttal to the rebuttal, one would have to assume you have no valid reply. Comments on blogs don’t count.
G&T’s published full reply here:
http://arxiv.org/PS_cache/arxiv/pdf/1012/1012.0421v1.pdf
One good method of extermination is starvation…….
Only rarely will any of the vested interests on any side change their minds, but that is not the battlefield. Who influences the minds of the general public which gradually absorbs information to influence behavior and voting preferences? I feel very safe and comfortable saying the Dragon Slayers are on the winning side of history.
At what point will I accept an apology from honest academics in the climate community and deal with them reasonably? Sometime after Hansen and Mann and Jones and Trenberth and Schmidt and Gore and all the others are removed from public funding and take their proper (shameful) place in our mad and chaotic human history.
No pressure.
Ken, you mistake the influence of the skydragons on the broader issue of AGW skepticism. It is very small. The skeptical arguments that have influence are associated with climate sensitivity and feedbacks, and understanding natural climate variability.
Individual academic scientists have nothing at all to apologize for, they publish their scientific research, almost always with caveats, and scientific understanding increases as hypothesis are confirmed or rejected, models improve, the observational data base improves, and our theoretical understanding increases. Some individual scientists are overconfident in their results, this is not surprising
The issue of concern is at the science-policy interface, which is badly broken in the case of climate science. This issue has been the subject of many posts here. If AGW policies have broken down, it is associated with problems at the policy – science interface (incuding the IPCC), and has nothing to do with faux scientific arguments that there is no greenhouse effect.
As someone who studies the diffusion and demographics of climate beliefs I am not sure that the influence of the dragons is small, or even what that means exactly. Most people who follow the debate know that this position exists, so I suspect that most skeptics give it some credence.
But of course this is a scientific question and a hard one at that. We basically do not understand how we come to understand what we understand. The flow of information and belief is too diffuse to be visible. The diffusion of scientific knowledge and belief is only now beginning to be studied. Note too that the policy-science interface does not have different people on different sides of it. Everyone is on both sides.
I think the best analogy is that the “Dragon Slayers” and their fellow travellers represent the “Young Earth creationists” of the movement…i.e., they are the people who believe things that don’t just require a selective reading of the evidence but things that are scientifically nonsense and demonstrably wrong.
Joel: The arguments do not seem like nonsense. Where is your demonstration?
David,
the fact that the 4 K cosmic background radiation from the Big Bang itself is absorbed by 300 K radar dish is all the demonstration one needs to know the Dragon Slayers are wrong.
Maxwell,
that would be nice except it needs to be isotropic. It appears that the most recent surveys are showing anisotropies to an excessive degree which could mean it is from more local sources compared to the theory.
See this post for a summary of why Claes work is nonsense: http://judithcurry.com/2011/01/31/slaying-a-greenhouse-dragon/#comment-95247 You can find more discussion by reading in that thread.
It is hard to tell whether this article is making a point worth contemplating or not. It seems to me the gist is that the net longwave flux is upward. That is, the upweard is bigger than the downward. This nasa presentation:
http://science.larc.nasa.gov/ceres/STM/2003-05/pdf/smith.pdf
does a nice job of showing the values. But whether that makes any difference at all in the arguments comes down to whether the climate models include BOTH the downward and upward flux, which is net upwards, or if they only take the downward into account in which case they would be totally wrong.
Since I don;t know whether the models include both, with the net being upward, then I don;t know whether the point of this article favors skeptical arguments or the AGW modelers.
Climate models include infrared radiative transfer that has fluxes in both the up and down direction. As I interpret it, the point of this article is completely consistent with the understanding of the radiative transfer models used in climate models, but deals with some semantic issues and tries to explain things from the perspective of skeptical arguments.
Vaughan Pratt
What evidence do you have for your statement:
The ice core CO2 evidence suggests massive CO2 swings as well as massive temperature changes – with the temperature often LEADING the CO2.
The 4% anthropogenic contribution must be compared with varying natural CO2 fluxes caused by variations in temperature and moisture etc. See Murry Salby’s presentation
JoNova provides some figs. Blockbuster: Planetary temperature controls CO2 levels — not humans
See William Happer The Truth about Greenhouse Gases
David,
Interesting article you link to – but can you tell me why the graphs cut off before the present time? Currently, CO2 levels are around 390 ppm. Where is the temperature rise that Salby claims raised the CO2 level from 280 ppm to today’s 390 ppm? Just eyeballing the graphs you linked to indicates it would have taken around a 10 C temperature rise to produce a 110 ppm CO2 rise. Yet the recorded temperature rise is nowhere near that large.
An alternative hypothesis, of course, is that the 110 ppm CO2 rise since the start of the Industrial Revolution is the result of human activity. Nah, we’d have to be burning giagtons of fossil fuels to cause a CO2 increase that large..
PhillipS
Here is an article with ice core graphs to 2000.
Amazing Arctic Reconstructions
Here are some more graphs on ice core data.
You can see the original data at NOAA Paleoclimatology
Ice core evidence ends when they were taken year/decades ago.
Murry Selby refers to other natural sinks and sources as well.
PhillipS
The latest detailed ice core is the West Antarctic Ice Sheet Divide Ice Core which has reached 3,330 m (10,925 ft). You can see the individual years. It will be interesting to see those results.
David Lappi reports on The big picture: 65 million years of temperature swings
This shows long term cooling over the last 65 million years, 5 millions and over the last 10,000 years.
Now why were are some so concerned with avoiding warming?
This is perhaps the next meme (or dragon) for JC to attack: that temperature led CO2 in the past (as no one denies), so CO2 can’t lead temperature in the future. We see this over and over.
Jim, I don’t know anyone who says that the Vostock ice core data (where CO2 is shown to lag temp changes) proves the opposite is impossible. What is said is: you can’t use the ice core record to support the case for CO2-caused warming.
Ken, can you help me understand why you say that the data proves we can’t use the ice core record to support the case for CO2 caused warming? Clearly something caused the roughly 8 C warming at the end of the last glacial period. The insolation change due to orbital forcing was only about 1 watt/m2, way too low to trigger an 8 C temperature rise unless you assume a very, very high climate sensitivity. It wasn’t a massive increase in water vapor because water vapor precipicates out at those low temperatures, and any large increase in precipitation would have shown up in the ice core and geologic record. It wasn’t the sun, and it wasn’t water vapor, so what was it?
If you are going to assert that all of the evidence pointing towards CO2 induced warming is wrong then you need to offer at least a hypothesis for a physical process that better explaiins ALL of the data.
I have some ideas, but it’s not an area I’ve studied in detail. I can say this: you can’t use data that shows temperature leading CO2 changes by 800 years to justify a case for CO2-caused warming, that’s all. I think the link between solar radiation and our climate is very complex…we don’t know all the variables yet. It’s far too early to claim certainty in anything. I’m much more inclined to believe small changes in solar output have effects much greater than small changes in the composition of rarefied gases in our atmosphere.
Anyone who looks at the ice core data should come away very humble. Mother nature is not always our friend–she has a very ugly and nasty temperament.
“Ken, can you help me understand why you say that the data proves we can’t use the ice core record to support the case for CO2 caused warming? Clearly something caused the roughly 8 C warming at the end of the last glacial period.”
We should know that CO2 can’t get below 150 ppm. And it’s claimed 270 ppm is “normal” or pre-industial. So you have a range of 120 ppm.
No one thinks adding 120 ppm of CO2 will increase temperature by 8 C.
“The insolation change due to orbital forcing was only about 1 watt/m2, way too low to trigger an 8 C temperature rise unless you assume a very, very high climate sensitivity. It wasn’t a massive increase in water vapor because water vapor precipicates out at those low temperatures, and any large increase in precipitation would have shown up in the ice core and geologic record. It wasn’t the sun, and it wasn’t water vapor, so what was it?”
Well the real question is what caused the cooling. And the cooling started about 50 million years ago, and the Antarctic due to continental drift move to where it is, starting about 50 million years ago.
So before 50 million years ago, all the ice in the Antarctic wasn’t there.
And btw, there is no ice on earth more than 2 million year old.
Antarctic has been gaining ice and losing ice over the last 50 million years- having periods of no permanent ice in the Antarctic during the warmer periods. And as ice mass or no ice mass the Antarctic has profound affect upon global climate.
We also have records that show a relationship between no sunspots and cold climate. So perhaps one reason for cooling, was first, the presence of the antarctic continent at the south pole and plus perhaps long periods of low or no sunspot activity. And addition you have the Milankovitch cycles.
Milankovitch cycles is mostly significant because of the earth’s unequal distribution of land masses and the relation to ocean areas. And I would guess due to Milankovitch cycles one could get dramatically different climatic patterns. One such change in climatic patterns might cause massive snow fall during the winter in Europe and/or North America. Having temperate region having prolonged period of snow cover could further alter climate.
So contrary to the common claim, it isn’t warm climate that causes variability but rather cooler conditions of the last few tens of millions of years has brought wide swings in global temperature in terms of tens of thousands of years. And there is no doubt that within a few thousand years, we will once again begin to return to ice age conditions.
Ken, no one, who knows what they are talking about, has used the ice core record to suggest CO2 leads temperature. They may have used the correlation between CO2 and temperature (like Gore has), but that is entirely different because there is no mistaking that they are tightly coupled in the climate system.
“…there is no mistaking that they are tightly coupled in the climate system.”
I agree Jim, CO2 and temperature are tightly coupled in the climate system.
That’s interesting coming from a skeptic. So you didn’t object to how Gore used his lift in his movie?
I didn’t see the movie.
If you think they are coupled, how can you think that anthropogenic emissions can affect atmospheric CO2. Do you think that natural sinks are limited (in Gt/year) and that they can’t handle the anthropogenic input? That they need more time (100s of years) to remove it from the atmosphere?
For those who didn’t see it, Al Gore showed, on a long large graph resembling a cinema screen, the CO2 record since the ice ages with minima near 180-190 ppm, increasing to pre-industrial values of 280, and current values over 380, and then used a lift as he gradually revealed large projected values in a relatively short time span with the line almost vertical, stating that the difference between the ice ages and pre-industrial (190 to 280) is several miles of Ice over New York (I think), then using the lift for dramatic effect to show the future values being a much bigger difference.
On your question, yes, natural sinks are limited, particularly in a warming climate. They can’t cope with more input being already saturated with respect to CO2.
“On your question, yes, natural sinks are limited, particularly in a warming climate. They can’t cope with more input being already saturated with respect to CO2.”
Why the ocean acidification scare then?
The ocean acidifies to stay in equilibrium with the increasing CO2 in the atmosphere. It is a tricky concept, but it is the ratio of CO2 in the ocean to atmosphere that depends on temperature, not the actual CO2 amount in the ocean. More in the atmosphere means more in the ocean. Warmer temperatures reduce the ocean fraction, but not enough to counter the increasing atmospheric CO2 effect.
Jim D,
You say:
“…it is the ratio of CO2 in the ocean to atmosphere that depends on temperature, not the actual CO2 amount in the ocean.”
Of course. So any anthropogenic (or natural) CO2 emissions into the atmosphere will go into oceans in order to restore the ratio that depends on temperature (NOT on anthropogenic input). It seems that you agree with me (and Salby).
Warming will decrease the ratio of CO2 in the oceans to atmosphere and consequently increase the concentration in atmosphere. If there’s anthropogenic input on top of the input caused by warming, the ratio ocean-to-atmosphere will still depend on temperature. Anthropogenic CO2 will not affect the ratio.
So, I’m back to my question:
Do you think that natural sink rate is limited and can’t restore the ratio, which depends on temperature, as you agree? That it takes 100s of years to remove anthropogenic CO2 from atmosphere?
Edim, so once the ocean restores the ratio, by using maybe half of what man added, what happens to the rest of it? It stays in the atmosphere. In the same way, the ocean can never completely remove what man adds because that would change the ratio.
This is the surface part of the ocean which overturns slowly due to the ocean circulation, and gradually is replaced by water that hasn’t been exposed to so much CO2 that can absorb more, but that just adds another time-scale over which CO2 can be removed. Once the ocean is acidified deeply enough it becomes much harder to get CO2 out of the system.
Jim D, thanks for the time to answer.
“…so once the ocean restores the ratio, by using maybe half of what man added, what happens to the rest of it? It stays in the atmosphere.”
Once the oceans (and other non-atmospheric reservoirs) restore the ratio, determined by climatic factors (mostly temperature of the reservoirs), any anthropogenic inputs (and other temperature-independent disturbances in CO2 fluxes) will be distributed between the atmosphere and the reservoirs exactly according to the restored CO2 atmosphere-to-ocean ratio. By constant climatic factors the ratio will be constant and the net flux will be zero. Adding anthropogenic influx will force the natural net flux to become efflux of exactly the same magnitude as the anthropogenic influx.
At variable climatic factors the ratio will be variable too and the overall (anthropogenic and natural) net flux will match exactly the amount needed to restore the ratio. The question is only how long it will take to remove the disturbance and restore the ratio.
If I understand the consensus position correctly, either the capacity of the reservoirs (oceans) is limited and it takes time (100s of years?) to restore the capacity or the maximum efflux rate into reservoirs is limited and it takes time to remove the anthropogenic input. I think neither is true and the ratio can be restored in less than ~3 years. Most of the anthropogenic input will be removed “locally” and almost immediately.
“In the same way, the ocean can never completely remove what man adds because that would change the ratio.”
Yes, but since the capacity of the ocean (and other reservoirs) is much larger than the atmospheric CO2 capacity, the ratio will not be affected significantly/measurably. In other words, sensitivity of the atmospheric CO2 concentration is much higher than the sensitivity of the oceanic CO2 concentration. So, the ocean will practically remove what man adds completely, once the ratio is restored.
Basically, it’s like anthropogenic H2O emission – it does not affect atmospheric H2O, because it’s determined by temperature.
I predict again that if the cooling continues, the percentage of the anthropogenic emissions removed by the ocean will increase and at some point all will be removed. Atmospheric CO2 will plateau. After that, even more than anthropogenic input will be removed (to restore the ratio) and atmospheric CO2 will start decreasing.
Yes this is probably worth discussing. One problem re dealing with this in the short term is that as of Mon, my schedule is insane until mid Oct. I will be needing guest posters for anything substantive starting next week.
Good luck with the start of school.
JimD,
You are really making a strawman and then congratulating yourself on knocking it over.
OK, perhaps that is just those people at WUWT, not here, who suggest that because the ice core shows temperature leads CO2, it can’t be the other way around. If we can unanimously knock this meme down on Climate, Etc., that would be fine by me. Next.
Well sure it can be the other way around. The major problem was that this graph was used extensively as evidence for Co2 driven climate, even after the 800 year lag was shown. I do remember realclimate people still banging on this point, as if there was a sudden blackout of logic.
Of course, their “logic” dictated that because their models couldn’t represent reality without that CO2 added on effect, therefore it was evidence for the CO2 ´drives temperature thesis.
As I mention elsewhere on this thread, the graph was used to show a correlation (at least by Gore), which is an OK use if you don’t go too far with cause and effect that can only be determined by lags. I doubt anyone who knows anything about Milankovitch cycles would say CO2 drove the ice ages, and if RC had people saying that, they would not be the experts.
JimD,
And perhaps it is only the AGW true believers who cling to the idea the ice core proves that CO2 is causing a climate crisis.
The ice core CO2 evidence suggests massive CO2 swings as well as massive temperature changes – with the temperature often LEADING the CO2.
David, you may have overlooked the word “century” in my “CO2 was not under any great pressure to change rapidly in a single century”. You’ll have to point out to me the century in the ice core data showing anything remotely near the 80 ppmv rise we witnessed between 1900 and 2000.
And bear in mind that the temporal resolution of the ice core data is only 70 years, making it hard to even tell what sort of change could happen in a century. You need a window of several hundred years to even begin to see patterns in the ice core data.
As far as T leading CO2 in the ice cores, of course, that’s what Milankovitch theory predicts. AGW theory predicts that anthropogenic CO2 leads T, without however ruling out the possibility that natural variations in T, e.g. due to ohmic heating by geomagnetic secular variation, could lead corresponding natural CO2 variations. But in any event not by 800 years; the IPCC suggests using 20 years for the anthropogenic impact though to me the data suggests more like 25-30 years while the GSV variations we’re aware of today involve at most 80 year periods and less.
With regard to the lag between heating adn CO2 rise, I’ve never had a problem with the theoretical argument that the temperature change could begin for one reason (Milankovic / albedo change or ocean circulation variations) and then be extended because of CO2 -related heating. However, there is also the other lag, that temperatures begin to decrease while the CO2 levels continue to rise (at least on the assumption that ice core derivations of temperature and CO2 are reasonably reliable). Surely this is an indicator that the climate sensitivity to CO2 increase has to be relatively low, and certainly points against the ‘tipping points’ and positive feedbacks that are often publicised.
Has anyone actually attempted to derive a sensitivity based on this turn round (i.e. what happens around the temperature peaks) – if we have a reasonable idea of the rate of change of temperature, rate of change of CO2 and maximum amount that can be attributed to natural variability, surely it should be possible to put an upper bound (at least) on the CO2 insulating effect*?
* In my opinion, a better phrase than the ‘greenhouse effect’, which is probably the poorest bit of terminology in the whole AGW discussion. Even worse than ‘back radiation’.
Vaughan Pratt, 8/14/11, 1:05 am, Vaughan Pratt
Vaughan, you are fostering one of IPCC’s fatal errors. RSJ, IPCC’s Fatal Errors, http://rocketscientistsjournal.com/2009/03/_internal_modeling_mistakes_by.html . Heavily smoothed data are not directly comparable to lightly smoothed data. The slow closing of the firn is a mechanical low pass filter on the ice core records with a time constant of 30 to 1500 years, depending on the accumulated snow fall. Modern instrument records, at least since Keeling’s time, have a time constant of one minute in the manual mode, and much less in the automatic mode. Furthermore, the ice core record is sampled with a long interval — 1450 years at Vostok. The modern record is relatively speaking continuous, and averaged for most purposes over one month. As a result the modern record is a single transient sample with a probability of 7% of an equivalent even being sampled at Vostok. That the modern record didn’t exist in the paleo record is valid, but with a confidence level of 7%.
The mechanical low pass filter in the ice core records can’t be reversed. If you want a comparison of any validity between the ice cores and, say, the MLO record, you would want to first pass the MLO data through a low pass filter with a time constant of 30 to 1500 years. This is but a thought experiment, but sufficient at that.
However, different places where ice cores have been drilled have different rates of snowfall accumulation and hence different time constants for the low pass filters. Does it seem very plausible to anyone that the actual CO2 levels have conspired in such a way that these different data are in good agreement with each other and there is never a period long enough when the CO2 levels remain above 300 ppm so that it shows up in the various low-pass-filtered data?
And, does it seem plausible that ever since we started emitting CO2 into the atmosphere, nature has conspired to absorb all of it but then also conspired to independently decide to emit into the air consistently about half of what we emit each year into the atmospher?. (Yes, there is some annual variability but it is remarkably consistent once you average over several years.)
That’s one heck of a natural conspiracy theory!
Vaughan
Regarding speed of change, I found the following:
from Ice cores, CO2 concentration, and climate B. Geerts and E. Linacre
That appears to be more than thirty times faster than in the 20th century.
In his 2011 ACS presentation, The geological context of climate change as a basis for policy Bob Carter shows geological records of CO2 being about 16 times higher than present about 430 to 550 million years ago.
That’s a rapid change in CLIMATE, not CO2 levels, and furthermore it is a rapid change in LOCAL climate. I think the evidence is that those rapid climate changes were likely a shifting of heat around in the climate system (e.g., due to changes in ocean currents), with the global temperature change being a fair bit less.
“I don’t believe their arguments impress the swing voters in the climate debate as convincingly as they might.”
More speculation in climate science that is really just politics. Just what we need. Yawn.
Andrew
Everyone’s entitled to an opinion.
Last time I tried this posting, it did not get much attention. Maybe that is what it deserves. But let me try again anyway.
The earth resides in space, and the only way it can receive and get rid of heat is by radiation. Let us suppose that the earth receives an amount of heat, E, where E is a rate of heating. If the earth is in equilibrium, then it must emit exactly E, or it’s temperature will change. Some of this heat is radiated directly from the earth’s surface, through a series of windows in the atmosphere where greenhouse gases do not absorb radiation. This part of the energy would not be affected by adding CO2 to the atmosphere. But the majority of the energy is emitted from the somewhere else in the atmosphere, and this must be transmitted through the atmosphere from the surface to wherever it is radiated from, and this process will be affected when more CO2 is added. Let us denote the energy that is emitted from the TOA as Et.
The earth will be in equilibrium when the earth has a temperature such that exactly Et leaves the earth’s surface, is transported to wherever it is radiated from, where the temperature of there is such that exactly Et is radiated into space. Now suppose that the amount of CO2 in the atmosphere is suddenly doubled. According to this theory of greenhouse gases, the transport of heat from the earth’s surface to wherever it is radiated from will be inhibited, and less heat will reach there. Let us call this reduction delta Et. Two things will happen. Almost immediately, the temperature of the place doing the radiating will decrease so that exactly (Et – delta Et) is radiated into space. At the same time the earth will accumulate heat at the rate of delta Et. Over time, the earth’s surface will heat up, until exactly Et is once again transmitted to the whevever the radiation escapes from, the temperature there is restored to it’s original value, and exactly Et is radiated out into space. A classic example of how the greenhouse gas effect works.
What is wrong with this idea that greenhouse gases work, not by heating the earth’s surface by back radiation, but by inhibiting the heat from getting to where it is radiated out into space?
The problem for the CO2 model is that the atmosphere is already almost totally opaque at the frequencies at which CO2 absorbs. There is very little energy available for any increased CO2 to absorb.
Ok, that is interesting, where is your evidence for this?
You are now where the science was about 60 years ago, which I guess is progress. That was before it was understood that the wings of the absorption lines matter too and there is always a part of the wings where it is not yet saturated. However, more importantly, the issue is not whether the radiation gets absorbed once or not at all. Multiple absorptions and emissions must be considered. What matters is in fact the level in the atmosphere where the radiation is able to successfully escape to space without being absorbed again. That level rises as one adds more CO2, which means that the emission is occurring from colder regions and hence is less (by the T^4 dependence of radiative power on temperature).
Jim Cripwell, your interpretation is fine and more general in including the importance of what goes out to space. The backradiation idea is a surface-centric view that is really only part of the more full picture that you lay out. It is often said that the atmosphere insulates the surface more effectively when CO2 is added, which is along the lines that you have suggested.
Jim – The Earth receives thermal energy from the sun and from IR back radiated from the atmosphere at altitudes varying from less than a millimeter up to many kilometers. For it to “accumulate heat at the rate of delta Et”, one or both of those must increase. If it’s not the sun, then it must be the atmosphere – otherwise the Earth would have no way of knowing that it is supposed to warm up. This extra heating arises because there are more CO2 molecules emitting energy isotropically (some of it directed downwards), and to a greater extent because the average emission from the CO2 molecules is greater as a result of their increased temperature – the latter due to the fact that CO2 molecules above them are intercepting IR that would otherwise escape to space, and sending some of it back down to lower levels of the atmosphere.
The above is a qualitative description of what can be computed quantitatively on the basis of the radiative transfer equations, atmospheric CO2 concentrations, the absorption coefficients at different wavelengths (including pressure and temperature broadening effects), and atmospheric temperature profiles, as well as a few other modifying factors.
“This extra heating arises because there are more CO2 molecules emitting energy isotropically (some of it directed downwards)”
That GHGs emit energy isotropically is repeatedly stated during this sort of discussion. There are two kinds of radiative emission: spontaneous emission (which would be expected to be isotropic), and stimulated emission (which would not be expected to be isotropic). Has anyone actually investigated the behavior of CO2 in the atmosphere under the influence of the upward-directed IR flux to see if that flux gives rise to stimulated emission of radiation from CO2? Because if the overall radiative emission from CO2 is not isotropic, but is biased upward, the result would be a lower amount of “back radiation” and a reduced heating of the surface in consequence. Stimulated emission of radiation can occur without actual lasing, and CO2 lasers exist.
Curious – The vast majority of IR photon emissions from GHGs arise as a result of excitation from collisions with energetic neighboring molecules such as N2 or O2 – i.e., they are a function of the temperature of the atmospheric layer where they reside. Only at very high altitudes is the fraction of emissions that result directly from photon absorption rather than temperature greater than minimal. I’m unaware of any reason why GHG emissions should be appreciably biased upward (or in any other direction). Do you have any reason to think otherwise?
Fred – When a CO2 molecule in the atmosphere is in an excited state such that it can emit an IR photon of a given frequency, and it is close to the surface, it is also immersed in an upwelling bath of IR photons of similar frequency from the surface. If such a CO2 molecule should interact with such an upwelling IR photon there would be at least a theoretical possibility of a stimulated emission of an IR photon from that CO2 molecule. Such stimulated emissions are predominately at the same frequency and with the same momentum, ie: in the same direction, as the stimulating photon. What I am, admittedly, conjecturing is that when the surface is warm and emitting IR photons upward, those photons will set off a cascade of stimulated emissions, also upward, which will result in an overall asymmetry between the intensity of upward IR emissions in the atmosphere, and downward emissions.
Curious,
but we’ve measured basically equal flux in both directions, away from the surface and towards the surface from above. So stimulated emission should be working in both directions almost equally. There should be no such asymmetry.
Stimulated emission is not the same issue than that of the origin of the excitation. Stimulated emission is significant only, when the electromagnetic fields are very strong as they are in lasers. We are many orders of magnitude further from the significance of simulated emission than we are from the significance of emission based on absorption in incoming photon. No ordinary light source or heat source can produce light or IR radiation at the level, where stimulated emission is significant, for that we need lasers with its high quality mirrors at both ends and pumping at a high power density.
CO2 lasers are based on same principles as other lasers, they are only technically different from the solid-state lasers and other types of non-gas lasers.
Some terrible language again. My English is not quite that bad, but I forget to read, what I have written, before I post.
What about the earth’s crust and core? It is measured to be hotter the further down you go. This is supposed to be due to pressure. Why is that not part of the discussion?
because the effect on the climate energy budget by the Earth’s interior is completely trivial.
Only when the interior creates a significant volcanic eruption will the interior have any impact on the climate.
Because the amount of heat reaching the earth’s surface from its core is minute when compared to the amount coming from the Sun. I’m no geologist but my understanding is that one of the reasons the earth’s core remains so hot is nuclear fission.
Fission is the Sun’s thing. The Earth is pressure.
Kermit,
Fusion drives the sun, not fission.
The exact mix of processes that keep the interior of the Earth hot are not completely known,but radioactive decay including fission play an important part.
Fusion is the Sun’s thing.
okay, my apologies.
The coldest place on the moon is 62 Kelvin according to a Discover article and is the coldest place in the solar system (apart from 2.7 Kelvin in space I presume). This is in the south pole where there is some permanent darkness in large crater shadows. It would seem that if the earth were without atmosphere like the moon that would possibly be the minimum temperature from the moon itself – whatever the process. This would indeed be a third fireplace and a fourth being the background cosmic X-ray radiation that starts us off at 2.7 Kelvin.
Given the size of the Earth compared to the moon, one should be able to further refine that 62Kelvin to something higher. Unless Earthshine is the cause. I’ll assume this is a common calculation and most here know that the answer, but I don’t know. Please, let me know what this base temperature of the Earth without atmosphere is (excluding the chemical and biological activity on the Earth too).
Now that we have got the fission thing out of the way I should say something about pressure. Compression raises the temperature of a substance but continued pressure does not create heat (to do so would violate the first law of thermodynamics). This is easy to demonstrate. Let the air out of a bicycle tyre and then inflate it quickly with a hand pump. The pump and the tyre will be hot or at least warm. Now leave the inflated tyre in the shade for a few hours. The tyre will be at ambient temperature again but the air inside it will still be under pressure.
The high temperature inside the earth may in part be caused by residual heat from the original compression when the planet was formed combined with the insulation properties of the crust and mantle. However the high pressure does not provide an ongoing source of heat.
Fusion is the Sun’s ‘thing’.
A lot of the heat in the mantle is from radioactive decay – certainly different from fission.
As I understand it radioactive decay that results in the emission of an alpha particle ( a helium nucleus) is fission. Admittedly emission of gamma rays and beta particles is not.
OK that was wrong too. The definition of fission requires that the daughter particles be of approximately equal mass. This is not the case in alpha decay because the alpha particle is much lighter than the remaining nucleus.
Fission does occur naturally but it is very rare.
So summarising:
Pressure does not provide a ongoing source of heat in the mantle or the core.
Radioactive decay does provide some of the ongoing heat.
Chief,
Thank you for clarifying and correcting my statement implying nuclear fission was a significant factor in the Earth’s interior heat budget.
There is strong evidence natural fission has occurred in the distant past,
http://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor
but we have no evidence that it is more than very rare at best.
I made the mistake of placing radioactive decay in the family of fission reaction. That was incorrect.
From recollection of some first year geology lectures, the contribution to the Earth’s surface from geothermal heat is something like 0.3W/m2, so can be ignored as trivial in this discussion. The main reason for the inner planet being hot is decay of long-lived radioactive elements, with residual heat from accretion (and hence pressure) being long gone. Lord Kelvin’s famous miscalculation of the age of the Earth was based on an estimate of heat loss from the assumption that the heat was caused by the pressure build-up of planetary formation – he was unaware of the presence of radioactive elements that continued contributing to the heat source within the planet.
Fission is not known in the inner planet, although there is at least one location where a natural fission reactor developed in the Earth’s crust (an initially uranium-rich sandstone in Gabon iirc – the Oklo natural reactor). Irrelevant as a heat source, but an interesting aside.
Alistair Fraser was a professor of mine in college. He and Craig Bohren were/are some pretty big names in the field that were teaching at the same time when I was at Penn State. Prof. Fraser was one of the early adopters of the internet and self-designed websites for use in class. His ability to communicate online was ahead of his time, and extended well beyond his retirement.
Ben Franklin was noted as saying, “You want to become famous? Write something worth reading, or do something worth writing about” … Of course, you can always stick it on the internet too.
Let’s get our definitions straight, OK? The term ‘back radiation’ refers to the mystical properties that must exist if fears of runaway Global warming are not to be confused with the superstitious fears of whitcbdoctors. That is, ‘back radiation’ is shorthand for reason down the swirling vortex and worshipping a golden calf on the altar of ignorance.
Not even wrong.
Yes, as Wm Starck observed climatelogy is a cargo cult science.
So, Wm is not even wrong. Surprise Eli
Wag
“Let’s get our definitions straight, OK? The term ‘back radiation’ refers to the mystical properties that must exist if fears of runaway Global warming are not to be confused with the superstitious fears of whitcbdoctors. That is, ‘back radiation’ is shorthand for reason down the swirling vortex and worshipping a golden calf on the altar of ignorance.”
Let me see if I can help you. I wont even talk about global warming. Lets start with this
“http://en.wikipedia.org/wiki/Backscatter”
And I will give you a practical military application, one that I’m familar with.
Let’s take a plane flying at 10K feet. The plane is hot. It radiates at different wavelengths: ( hot metal, hot gases, aero heating)
http://en.wikipedia.org/wiki/Infrared_signature
Software like this, used to be secret or TS/SAR
http://sourceforge.net/projects/osmosis-project/
Anyway, the radiation leaves that plane and then it has to travel through the atmosphere. The same way a cell phone signal has to go through the atmosphere, the same way a radar beam has to, same way sunlight has to. What happens to radiation when it transfers or propagates through the atmosphere? do we know? yes. we build things every day and use things every day that rely on a sound proven understanding of the propagation of radiation through the atmosphere. In some cases we use the fact that the atmosphere interfers with long range transmission to build short range “covert” transmission systems.
http://portal.acm.org/citation.cfm?id=1720092
Simply, we know how radiation propagates. Our soldiers lives depend upon this science.
When you shine a flashlight on a mirror, do you see light come back? Yup. that is specular reflection. You ever drive late at night in the fog?
How come the light doesnt go through the fog? That would be like diffuse reflection, or backscatter.
So back to the plane. At 10K feet what happens if I try to see the plane’s IR from the ground with a sensor? Well That IR has to get to the sensor. How does that work? well as the energy comes toward the ground some gets
‘backscattered’, some gets absorbed, and some makes it through. What if a cloud passes overhead? Well the IR gets blocked. Why? well clouds are full of water and h20 does a great job absorbing and deflecting and reflecting IR. In order to keep our pilots safe from nasty russians on the ground, the airforce decided it would be a good thing to understand how different molecules react to different wavelengths. They built a database: Its called Hitran. And, we needed tools to predict what would happen to the IR as it went through different kinds of atmospheres ( standard, tropical, etc) So we had another tool MODTRAN. That engineering tool allowed us to model and then test how IR ( say from a plane) would transmit down from a plane to the ground. It’s known physics. It works. You use it every day.
Now, That same plane radiates UPWARD as well as downward. What happens to the IR that goes from 10K upward. Well, the same thing happens. Some of the IR get scattered back, some gets absorbed and some gets transmitted. Why is this important? This is important because there might be an airplane above me at 50K feet looking down. or a space platform looking down. The person on the ground looking up will see one thing. That is driven by the atmosphere between the ground and the plane at 10K. But the plane at 50K looking down will see a different image. Why? because the IR from the plane goes through an atmosphere that may be different. With different amounts of C02 and water and clouds, the plane at 50K may see the plane at 10K, whereas the guy on the ground behind the cloud sees Nothing! And, if I’m designing at plane I might also look at trying to use C02 to hide the plane. Why? because the physics the airforce relies on tells me that C02 does a good job at backscattering and absorbing IR. I might even spend a bunch of money testing this. here is a very nice paper
http://dspace.library.iitb.ac.in/jspui/bitstream/10054/613/1/5740.pdf
So to protect this wonderful country and our individual liberty, people like me had to believe in backscatter. We had to use the very same physics ( Radaitive Transfer equations) to calculate how IR would pass through the atmosphere. So, backscatter is real. The IR that leaves the surface of the earth heads toward the sky, but along the way it gets absorbed, scattered back, and eventually it get reradiated to space.
By your analogy that heat engine in the sky we call the Sun is like a hot plan dashing through the airspace. And, that is a bad analogy. When it comes to the transfer of heat we really should at least try to honor the Laws of Thermodynamics.
A study of the Earth’s albedo (project “Earthshine”) shows that the amount of reflected sunlight does not vary with increases in greenhouse gases. The “Earthshine” data shows that the Earth’s albedo fell up to 1997 and rose after 2001.
What was learned is that climate change is related to albedo, as a result of the change in the amount of energy from the sun that is absorbed by the Earth. For example, fewer clouds means less reflectivity which results in a warmer Earth. And, this happened through about 1998. Conversely, more clouds means greater reflectivity which results in a cooler Earth. And this happened after 1998.
It is logical to presume that changes in Earth’s albedo are due to increases and decreases in low cloud cover, which in turn is related to the climate change that we have observed during the 20th Century, including the present global cooling. However, we see that climate variability over the same period is not related to changes in atmospheric greenhouse gases.
Obviously, the amount of `climate forcing’ that may be due to changes in atmospheric greenhouse gases is either overstated or countervailing forces are at work that GCMs simply ignore. GCMs fail to account for changes in the Earth’s albedo. Accordingly, GCMs do not account for the effect that the Earth’s albedo has on the amount of solar energy that is absorbed by the Earth.
Actually Mosher’s analogy is right on. Just like in Mosher’s analogy I don’t expect the IR signature of the plane, from the moon or from Betelgeuse to warm the surface of the Earth any more than I expect a -50 degree sky to warm my section of the Earth that is at about 33 C right now. I do know that when the night sky is -20 instead of -50 that clouds have moved in so the temperature here will cool down slower. Why? Because the clouds are intercepting more outgoing radiation than the clear sky. If it stays cloudy all night the temperature of the clouds will drop as the temperature of the surface drops. If the clouds were warming the surface, I would expect the temperature of the surface to increase as the temperature of the clouds decreased. So I have no real problem with back radiation other than when someone says it warms the surface. The sky does have a temperature so it emits IR like any object that has a temperature. The higher the temperature of the sky the lower the net outgoing radiation. It is only when the net is positive incoming that the surface is being warmed.
Call it semantics, but it is simpler to stick to the basic physics.
You canot support a false analogy with another. A blanket of cloud cover may ‘warm’ the night but the surface of the Earth will cool all the same throughout the night.
By your way of thinking, if you put a blanket on a dead body it will warm. And, if you add more blankets you run the risk of the body bursting into flames due to runaway warming.
The problem all will run into in trying to defend delusinal and their unscientific beliefs about global warming alarmism is their failure to grasp the obvious. We know what causes global warmnig and global cooling. Nominally, it’s the Sun, stupid.
Vaughan Pratt
Re: “Well, moving the ice further away reduces its cooling effect on you and your warming effect on it, so presumably that number must be reconciled with the evident fact that you’re warming the ice, not vice versa.”
“Reduces its cooling effect” is due to the subtended solid angle being reduced by the finite block of ice being further away.
When radiating to the sky at 4C, the subtended solid angle of the sky does not change much when you are above the earth, so this is a confusing metaphor. May I encourage you find more helpful illustrations.
(PS For precise calculations of the global atmospheric absorbance or emission, there is some variation with angle due to the varying thickness of the atmosphere through which the radiation is transmitted. See Miskolczi’s calculations on Anisotropy in directional radiance.)
“Reduces its cooling effect” is due to the subtended solid angle being reduced by the finite block of ice being further away.
When radiating to the sky at 4C, the subtended solid angle of the sky does not change much when you are above the earth, so this is a confusing metaphor.
It wasn’t intended as a metaphor, only as additional confirmation that it’s the ice that’s cooling you and not something else, nothing to do with the atmosphere in that case. When experimenting I like adjusting as many variables as I can in case one of them has an unexpected effect that I’d overlooked. In hindsight it would have been less distracting to skip that particular adjustment.
Dr. Curry,
You ask some very interesting questions.
Here are some observations from someone who has been involved in the design and manufacture of industrial insulation for pipes boilers and storage vessels that may help with understanding this. I will go through this in small steps. Please feel free to show where the steps go wrong from your perspective.
First, the primary heat source is doing the work of heating. Everything else is cooling, just at rates based on thermal properties. A steel pipe, uninsulated, will lose heat very quickly. A steel pipe insulated with a good industrial insulation will still lose energy, but at a lower rate.
If you review this technical spec sheet for a quality mineral wool industrial supplier’s pipe insulation product, you will see the HL (Heat Loss) spec at differing temperatures, along with the graph showing behavior over temperature ranges.
http://www.roxul.com/files/RX-NA-EN/pdf/Techton1200.pdf
Note the ambient temperature set for the performance tests. Do you think that very many industrial catastrophes occur if the ambient temp goes from 75.0F to 80.0F, by the way?
The Earth is entirely heated for climate purposes by the sun like any other planet.
Earth’s surface happens to be covered in an ocean of gas and vapor ice and liquid- the atmosphere. The Earth, unlike a typical industrial application, heated from the outside source of the sun, so the insulator, the ocean of air and vapor/liquid/ice and dust that makes it up gets heated as directly as the surface does. Some of that heat in the atmosphere is re-radiated down as well as out. But the net flow is always out, away from the Earth. To say the insulation warms the pipe makes no sense. Yes, as the insulation warms it radiates, but so what? It is still moving energy out on a net basis. The AGW obsession is as if someone was looking at the flow of a great river, and decided that since there are eddies in the flow, the river is not really running to the sea.
To say the insulation keeps the pipe warmer, and holds the temperature longer, makes more sense. To say the insulation is heating up the pipe in any significant way makes little sense. You will never insulate the pipe to the point of a run away boil or steam pressure rupture. Turn off the furnace or boiler, and no matter how good the insulation, the pipe cools off.
But the Earth and its atmosphere is heated by the sun, so the energy passes through the atmosphere and heats it along with he surface. And the atmosphere does pass part of its radiative budget to the Earth.
Frankly that seems trivial in terms of energy budgets. The atmosphere acts to moderate what it is given. It adds nothing. If the atmosphere was not over the Earth, the energy budget hitting Earth would be identical. It would simply, like the uninsulated pipe, lose its heat much more quickly, as does Luna or Mercury,when the sun sets or on the dark side.
Insulation, while generally manufactured to high standards, is still variable from batch to batch. The slag, the binders, the protective wrap over the insulation all influence its R value. But that seldom causes problems in the field, as long as the variation is not extreme.
When I observe the numbers offered as to how much change CO2 has made in the energy budget due to its recent increases, the word that comes to mind is ‘trivial’.
And that is what the climate record of the past 150 years shows: Trivial typical changes in climate manifestations. Nothing dangerous or dramatic or unusual.
When I see your projection of where CO2 ppm will be at the end of the century, the question comes to mind, ‘How can it grow to >800ppm in this period at an increase of ~2.5ppm per year?’
And in light of Salby’s soon to be published review of CO2 budgets, perhaps even the assumptions underlying CO2 will need to re-examined.
Sorry about the long post, but there are really better things to critique AGW with than the dead dragon.
I think the idea of the atmosphere as an insulating layer is better as an engineering analogy than a greenhouse. Adding CO2 increases the insulation. You may think that 4 W/m2 from doubling CO2 is trivial, but remember it is sustained and corresponds to a 1 degree increase in surface temperature, which is not trivial in climate terms and can cause feedbacks that amplify it, mostly because water vapor is a greenhouse gas that is very responsive to temperature,
Jim D,
4watts in a multi hundreds watts system is trivial by definition.
ooops hit submit too soon.
Additionally, the 4 watts is not additional energy to the system, it is reduced loss on the way out.
BTW, I thought the CO2 impact was different from 4W?
I degree in climate is by no means trivial.
I mean one degree, and doubling CO2 changes the radiation by about 3.7 W/m2 at the top of the atmosphere, which translates to a similar order of magnitude change at the surface.
JimD,
1.0C in a system that has daily swings in many cases of 10’s of degrees and seasonal swings in tens is trivial.
Just as with eugenics, the AGW movement has extrapolated a crisis based on trivial data.
OK, we have 1 nearly degree in the last century with probably three more in the next. At what point do you think it won’t be trivial? It is fine to agree with IPCC WG1 about the three degrees, and argue with WG2 about its effect, if that is your position.
You raise the interesting question about how useful global average temperatures are in the first place.
As for the ‘probably three more’, I believe that assumption is not viable.
‘doubling’ is tossed around frequently. Doubling from what level? From 280ppm?
From the current ~390ppm?
So, when does it become non-trivial? The global temperature difference between our current climate and the last-glacial maximum is something like 5- 6 C. I would call the effect on here in Rochester highly non-trivial, given that we were under thousands of feet of glacial ice.
So what you’re saying is that you’re worried that we’re going to be buried under thousands of feet of ice if the temperature increases a few degrees?
If not, then exactly what are you saying?
I am saying that global changes in temperature that might seem small to some people can lead to very large changes
…in the world in which we live.
I would suggest the local temperature at Rochester is now a lot more than 5- 6 C higher than it was during the last glacial maximum.
The global average says little to nothing about local temperatures, and furthermore it’s determined by local temperatures – not the other way around.
Peter,
You are probably correct about Rochester. However, the point is that the same will be true of some places for a given rise due to AGW: It will be larger some places than others. For example, it will be larger over continents than it will be over the oceans.
Joel,
We have seen, if the current understanding is correct, CO2 go from ~280ppm to ~390ppm.
Has Rochester suffered in any way from this?
No. Are the seasons changing in dangerous ways? Is rain, drought, snow, heat or cold changing in ways that are going t make you move away?
Will 5-6 degrees put Rochester under ice?
No.
I and the flora and fauna and the agriculture are adapted to the Rochester climate the way it is, thank you very much. And, I think the people in Bangladesh are adapted to the sea level where it is.
I agree that describing the atmosphere as an insulating layer is better analogy than a greenhouse. However, I disagree that adding CO2 increases the insulation. It affects radiation, but it also affects convective and evaporative heat fluxes and the net result is not known.
Furthermore, it seems that adding CO2 to the atmosphere does not significantly affects atmospheric CO2 – it’s driven by climatic factors.
The difference between having GHG insulation and not is 33 degrees C. So it stands to reason that adding CO2 would add more, unless we have suddenly hit a ceiling.
Jim D
That is what is said if you follow a long line of “iffy” assumptions.
Read Postma paper 1 for a more balanced outlook.
Postma uses a flawed argument to state that the surface temperature is the current-day surface temperature even with no greenhouse gases. He doesn’t seem to realize that the surface temperature is not determined solely by atmospheric mass. Very weird stuff.
Jim D
Postmas point is the 255K radiating temperature is for the Earth/Atmosphere ensemble not the surface temperature.
He does the calculations to show for instance that at the solar zenith, earth temperatures reach 80C for an area the size of the USA facing the Sun.
Given the reality of Oceans and earth atmosphere and surface thermal energy retention the 33K greenhouse effect seems a little exaggerated
He thinks the radiating altitude of 5 km is independent of greenhouse gases.
Jim D says (of Postma)
“He thinks the radiating altitude of 5 km is independent of greenhouse gases.”
Perceptive comment as usual, thank you.
Where would it be if a full contribution from the greenhouse gases was included?
It would be at the surface if there were no greenhouse gases. He didn’t seem to know that obvious fact.
Jim d says
It (-18C) would be at the surface if there were no greenhouse gases. He didn’t seem to know that obvious fact.”
You are ignoring the heat retentive properties of the Earth system.
He covers the topic of the surface at great depth.
For instance at the solar zenith a sun facing part of the earth the size of the USA is at 80C.
Is the Earths water going to instantly freeze down to -18C – get real
Bryan, you seem not to be skeptical of Postma. I am. His time-varying issues raise no new science regarding the energy balance and mean state. He only has to look at the Moon to see what a GHG free state would look like. Atmospheric mass wouldn’t help the Moon to be warmer if you added a GHG-free atmosphere there somehow.
Jim D says
“He only has to look at the Moon to see what a GHG free state would look like. Atmospheric mass wouldn’t help the Moon to be warmer if you added a GHG-free atmosphere there somehow.”
What do you think would happen to the maximum and minimum temperatures on the Moon if its rotation period was 24 hours?
Does anyone have a program model to run this test?
SkepticalScience will have an extended breakdown of Postma’s paper, scheduled to be published there Wednesday.
I don’t think it’s any better. A blanket at night can keep you warm but a greenhouse in the night gets cold.
Maybe a gore-tex blanket is better example but probably not.
We left an iPod Touch in the sun the other day and it was so hot it burned your fingers but the table it was on was not very hot at all. Wrapping it in a blanket has no effect on its temperature.
Kermit says
“a greenhouse in the night gets cold.”
True and sometimes the temperature inside the greenhouse is less than the ambient outside temperature.
Edim,
CO2 will, on balance, increase the insulating potential of the atmosphere.
I am not convinced hunter. Too complex to be certain.
And even if it will, how significant is this increase?
Furthermore I think temperature determines atmospheric CO2. That means CO2 can’t really be increased at constant climatic factors. Any disturbance in fluxes (anthropogenic or not) will be removed.
Edim,
It is not too complex.
It is established by experiment experience and physics that CO2 will act as an insulator in the Earth’s atmosphere.
As you point out, it is the size of impact that is significant.
The impact from the past ~150 years has been trivial.
Temperature certainly regulates CO2, as does biosphere activity, the availability of geologic CO2 sinks, ocean temperatures, etc.
That does not mean we cannot put in more CO2 than the system can sequester or consume in a fixed period of time.
But that said, none of this supports a catastrophe caused by CO2.
I think it’s too complex. We agree on almost everything else. Increased atmospheric CO2 will VERY likely reduce Earth’s radiative heat loss to space, all other things held constant. But all other things can’t be held constant.
I think that we cannot put in significantly more CO2 than the system can sequester in a fixed period of time, at the anthropogenic CO2 emission rate. I agree 100% with Salby on this point, not because I am not sceptical, but because I came to the same conclusion few years ago.
Hunter –
You are correct that insulation will not increase the temperature of a pipe to greater than the temperature of water flowing through it.
Similarly, the insulating properties of the atmosphere will not increase the temperature of Earth to greater than that of the Sun.
To be more accurate, the maximum temperature would only be around 400 C at the Earth’s surface. At that point, all of the oceans would be water vapor and Earth could not get any more insulation from water vapor.
To be still more accurate. My 400C calculation was based on the temperature explicit form of the Antoine equation for boiling water.
Surely you are not suggesting that CO2 is going to cause the seas to boil?
Hunter –
Of course, not. My guess is that with an overall albedo of ~.8 for 100% cloud cover, a complete boil off of the oceans is not possible.
On the other hand, heat from volcanism, radioactivity, plasma flux ropes, a big meteor/asteroid strike, etc. will take awhile to get to top of atmosphere. Has somebody done these calculations? Not me.
BTW, Dr. Pratt said to address what you are thinking, not what you are saying. And I imagine what you were thinking was correct. That is, I believe you correctly understand Heat flow. However, I addressed your pipe/insulation model which was not correct.
Sorry.
If the greenhouse effect from CO2 is real, the evidence must exist in the paleo record. It is simply not possible that there have not been massive releases of CO2 due to natural causes many times in the past. If the greenhouse effect from CO2 is real, then in the long history of the earth there would be clear evidence that CO2 leads temperature.
Why do we not see this in the paleo record? Why do we find that CO2 lags temperature, but not that Co2 leads temperature? Why in the long history of the earth have we not found evidence in the paleo records that CO2 leads temperature if the CO2 greenhouse theory is correct?
Is it just possible, that our knowledge of CO2 and radiation budgets is an incomplete picture of climate? That water, sun, air, earth and life are the drivers of climate on planet earth? That they interact in such a fashion that the earths temperature has remained at 22C or 11C for most of the past 600 million years, and our present 14.5 C average temperature is far from typical or average. It is simply the result of a brief warming in the middle of a series of ice ages.
A warming that is on balance a benefit rather than a danger to life. A warming that is responsible in large part for human prosperity. Is it really a coincidence that our modern prosperity began with the end of the Little Ice Age? In that respect it could be argued that warming is what drove human CO2 emissions.
There is a lot of evidence of CO2 leading temperature in the paleo record. Firstly volcanic periods, like the Permian-Triassic boundary that ended the Permian ice ages, and led to the warm Mesozoic Era, generally because these volcanoes increased the atmospheric CO2 concentration at least tenfold. Secondly, most of the last 100 million years since the Cretaceous has been a cooling trend, generally seen to coincide with a slow reduction in CO2. The CO2 was decreasing through natural sequestration, such as weathering, ocean sedimentation, and soil burial, and the temperature followed. No one has suggested this is the other way around.
The latest crackpot theory is that temperature drives CO2 and the lag is 30 years. Do the ice core records have this sort of definition?
A factor that occurs to me is the overemphasis on radiative transfer and a corresponding underestimation of the various thermal retention properties of the Earth system.
I picture the Earth daily heating cycle by this simple analogy.
An electric circuit with a resistor a diode and a capacitor.
The Sun facing side of the Earth changes gradually every half cycle.
This heating can be represented by the crest part of a sine wave the diode removing the trough half cycle.
The resistor represents the dissipative loss to space of degraded radiative energy.
The capacitor represents the thermal energy storage system.
The circuit is of course called a smoothing circuit.
By correct choice of resistor and capacitor the voltge across the resistor (Earth Temperature analog) is almost constant or smoothed.
I find this narative much more plausable than backradiation saving the Earth night side plunging towards -273C.
I feel that Professor Pratt’s point was missed by most readers. He was trying to explain why the conventional explanations of the “greenhouse effect” (which might be easier to explain if it were named the Arrhenius effect as that would not draw in confusing analogies to real greenhouses) lack persuasive power. More details of Professor Pratt’s position are given at:
http://boole.stanford.edu/pub/lgw.pdf
Suffice to say, he accepts thermodynamics and does not dispute the resonances of the C02 molecule.
Tom said:
I agree with Charles, why on earth have you allowed an article like this to be pulished on your blog, when clearly the author doesn’t understand basic physics ?
That’s not how I read his article. I thought it was making a point about the types of explanations that would communicate best with skeptics. His knowledge and skills in math and computing are probably better than those of most (all?) who call themselves climate scientists. And, I’d be willing to bet that he got better grades in physics than they did.
His was a post from a non-skeptic. The tone of the comments on his post illustrates some of the problems with the discussion of climate issues.
Chuck
In your last paragraph conclusion, does not the caveat “based solely on the temperature and CO2 records to date” include the huge assumption that CO2 drives temperature rather than temperature driving CO2. Based on my experience in high school I should have graduated from Ga Tech with honors. I neglected to consider a few other variables.
In your last paragraph conclusion, does not the caveat “based solely on the temperature and CO2 records to date” include the huge assumption that CO2 drives temperature rather than temperature driving CO2.
It’s not an assumption, it’s a calculation based on a very simple mechanism. In order to stay at the same temperature, Earth must shed as much energy as it receives. When GHGs increase, each photon leaving from each point of the planet, whether from solid, liquid, or gas, now has a lower probability of escaping to space, resulting in a decrease in radiation. The heat that doesn’t escape gradually heats the Earth, thereby increasing radiation until balance is restored. This is a simple and natural mechanism.
Notice that DLR gets no mention in this mechanism. I’ll say more about this below.
For each photon at any given wavelength leaving Earth from any given point of any given kind at any given temperature and altitude in any given direction through any given quantity of GHGs, we can estimate the probability that the photon will escape to space. We can further estimate the reduction in that probability resulting from increasing the GHGs. (GHGs are not independent hence one cannot analyze this independently for each GHG.) From this we can infer the net decrease in radiation resulting from the GHG increases. We can then estimate the increase in temperature needed to bring the radiation back into balance.
This is the mechanism by which increasing CO2 and other GHGs increase the temperature. It is only an assumption in the same sense that the falling of an apple from a tree is assumed to be due to gravity. It’s a very reasonable assumption once the principle has been grasped.
DLR plays no role in these calculations. It’s quite correct to say that DLR exists (that’s what my IR thermometer measured). It’s also quite correct that the extra photons that the extra CO2 prevents from escaping raise the vibrational energy of CO2 molecules. This energy is converted to translational, rotational, and vibrational energy of air molecules (of all kinds) when the CO2 molecules collide with them, by Boltzmann’s principle of equipartition of energy among all available degrees of freedom of each molecule. At STP they collide every 500/70 = 7 nanoseconds on average since air molecules move at 500 m/s and have a mean free path of 70 nm.
In this way the air is warmed.
Where the back radiation argument for global warming breaks down is the assumption that the additional warmth is conveyed to the rest of the planet by radiation. Clearly some of it is, but some of it is equally clearly conveyed around the planet by convection, eventually reaching the surface in the form of warmer air which then heats the ground by conduction via contact with the bottom millimeter or so of the atmosphere.
It is completely irrelevant what proportion of this extra warmth from the atmosphere reaches the ground via DLR as opposed to via convection and conduction. The math is independent of that proportion.
Nevertheless it is of independent interest to know that proportion. The two bottlenecks in getting an increase dT of temperature down to the surface are radiation and conduction. Given that the rate dT/dt of global warming is about a billionth of a degree per second, while the diurnal fluctuations are many orders of magnitude greater, convection cannot possibly be a bottleneck.
Ignoring feedbacks, we can estimate the rate dF/dT of change of heat flux F in W/m2/K as 4F/T (since it’s equal to the derivative of F = σT^4.) With F = DLR = 324 W/m2 and T say 270 K for the sake of argument, dF/dT = 4*324/270 = 4.8 W/K. (By all means replace this with a better estimate if you have one.)
Thermal conductivity of air at typical surface temperatures (the only place where conductivity is relevant) is roughly 0.025 W/m/K. Assuming a skin thickness of s mm at the surface, this becomes dF/dT = 25/s W/m2. In order for this to equal the 4 W/m2 of radiation rate dF/dT we would need a skin thickness of about 6 mm.
Being neither an atmospheric physicist nor a barefoot doctor I don’t know all that much about skin on the ground. However I would imagine that with even a slight breeze the skin is likely to be a couple of orders of magnitude thinner than this.
If so then we may conclude that almost all the warming of the atmosphere is conveyed to the surface by convection and conduction, and that DLR plays no significant role in global warming. In order for it to go the other way the air skin on the ground would have to be centimeters thick.
Put simply, a warmer atmosphere warms the ground by direct contact, with essentially no assistance from DLR.
While I realize this may not be the reason climate skeptics are skeptical about the role of DLR in global warming, they may derive some measure of satisfaction in the thought that for all they know their subconscious had done the math and was bugging them to speak up.
Based on my experience in high school I should have graduated from Ga Tech with honors.
What was your major? I went into physics at Sydney Uni based in part on coming 8th in the NSW external (LCE) physics honours exam (no idea what careers the 7 above me went into). Although I graduated with double honours in pure mathematics and physics (a 5-year program), computer science was just starting up as an academic subject when I graduated and I picked it as a more exciting field to get into than physics at the time.
Vaughan, seeing that you want a scientific rather than analogy explanation, let me give it a try. The surface has to warm before the troposphere can because the tropospheric temperature is tied to the surface by convective-radiative equilibrium that constrains the lapse rate. So your idea that CO2 directly warms the troposphere which then spreads to the surface has it backwards. (The stratosphere is unlinked to the surface, and has its own behavior). This is why DLR is so important. CO2 increases DLR as a first step in increasing surface temperature, which then increases convection and warms the troposphere.
In fact, suddenly adding CO2 has the immediate effect of cooling the atmosphere because it radiates more efficiently to space, but this also spurs on convection to equilibriate the lapse rate.
Jim D
Lets think of a solid hot surface and a solid colder surface both parallel and facing each other with an large air gap between .
Large enough for a measurable change to be detected if the composition of the air was changed.
Lets say the experiment was carried out in space so as to eliminate convection.
We change the composition of the air by adding or subtracting CO2.
We wait till each new steady state arrives.
We then measure the thermal energy flow from the hot to colder surface.
I’m honestly in some doubt as to what would be the outcome .
1. No change
2. Increased flow with trebling CO2 above atmospheric norm
3.Decreased flow with trebling CO2 above atmospheric norm
Any ideas?
If by flow, you mean radiative flow, I think the net won’t change, but upward and downward amounts increase with more CO2 canceling each other out in the net. I am not sure what the equilibrium profile would be, but it is either isothermal at the mid-point temperature or a linear T gradient.
Jim D
No H2O in mixture for simplicity
the main method of heat transfer here would be radiative for most situations.
This would be largely constant
However diffusive heat transfer (effectively collisions) best described by conduction would also be there.
Non IR active gases could only scatter any radiation intercepted.
IR gases could heat up the non IR gases thus assisting the diffusive flow
It seems that with no CO2 the diffusive heat transfer would be very small and slow.
It seems that with CO2 the diffusive heat transfer would be larger and faster.
The two processes diffusion and radiation seem then to work against each other and a balance point is reached
There must be tables made up predicting the overall flow given the gas mixture.
A bit like calling the process thermal conductivity figure but that would be the wrong term
The radiative properties of the solid surfaces and the temperatures of the surfaces would also have to be factored in
If the radiative surfaces had small emissivity its possible that the diffusive flow might be greater than the radiative.In this case adding CO2might cool the increase the overal heat flow
Last sentence should be
.In this case adding CO2 might increase the overall heat flow
The surface has to warm before the troposphere can because the tropospheric temperature is tied to the surface by convective-radiative equilibrium that constrains the lapse rate.
It takes only microseconds for heated CO2 to collide with nearby molecules and warm them. Heating takes place throughout the atmosphere, somewhat more at the bottom. Furthermore global warming is around a nanokelvin per second which will have no appreciable impact on anything to do with lapse rate at this time scale.
If you’re referring to the tendency of increased environmental lapse rate to decrease to the adiabatic lapse, the requisite convection takes on the order of hours to days, not seconds, even for large changes. For changes as small as those of global warming it will take so long as to be lost in the noise of other thermal fluctuations.
I agree that “it takes only microseconds for heated CO2 to collide with nearby molecules and warm them” but that is non-responsive to the fact that “the SURFACE has to warm BEFORE the troposphere can.” That fact invalidates your entire objection to DLR not DIRECTLY warming the surface, which is not part of the GHE model, thus it is a straw man argument on your part to claim that to be a flaw in that model.
It is in fact not any part of that model.
I agree that “it takes only microseconds for heated CO2 to collide with nearby molecules and warm them” but that is non-responsive to the fact that “the SURFACE has to warm BEFORE the troposphere can.”
Sorry, I’m not following this reasoning. The surface is warm to begin with, quite enough to emit photons that the CO2 can then capture. Are you claiming otherwise?
Vaughan,
As Jim D and several others have pointed out, the immediate consequence of an sudden addition of CO2 to the atmosphere is to strengthen the radiation from the atmosphere down to the surface. The surface starts to warm, and the atmosphere first to cool. The warming of the surface will then influence the atmosphere leading to a new balance, where both are warmer. The same order of influence applies also to infinitesimal increases of CO2 to the atmosphere.
The Earth system, which includes both the surface and the atmosphere starts to gain heat immediately as the IR flux to the space decreases. This happens for two reasons
– radiation from the surface and the lowest atmosphere escapes less to the space and is more often absorbed by the atmosphere
– the very highest level of troposphere and the tropopause absorb more of the radiation from slightly below and move the average origin of the radiation up tor the wavelengths of the strongest absorptivity/emissivity.
The immediate change at the top of troposphere is what is called radiative forcing.
Pekka – The word “cool” or “cooling” is sometimes used to mean different things. In the sense that I would like to use these terms in this discussion, when CO2 increases, less radiation escapes to space and more is directed downward. This includes IR upwelling from the surface, some of whose energy is now directed downward. As you state, this increase in energy release into the surface in response to impeded release to space can be thought of as “cooling” but the net effect can be expected to increase atmospheric temperature, because photon absorption, thermalization, and subsequent energy emission is a temperature-raising process. The increase in these events within the atmosphere is thus a warming effect.
The above requires increase in emissions to have been the result of increase in absorptions. While this is probably true in the troposphere, the opposite is the case in the stratosphere. Here, added CO2 responds to ambient temperature by increasing emission rates, but because the temperature is the result mainly of UV absorption by ozone, absorption has not increased significantly, and the result is a reduction in temperature. I’m unaware of any scenario whereby the same thing could happen in the troposphere, although it seems conceivable that to some extent, water vapor could temporarily duplicate the role of ozone. All in all, though, a warming troposphere would seem to be the first response to an OLR reduction from increased CO2. The surface responds much more slowly because of its higher heat capacity, and so the warming of the atmosphere via a warmed surface is probably a lagging rather than leading event in the changing dynamics.
In response earlier to Alex and Jim D, I stated that I remain open-minded to an alternative scenario, but so far, no mechanism that would result in a temperature reduction has been described. Increased DLR is not a mechanism when it is simply a response to reduced OLR. The response of the atmosphere to an initial OLR reduction will be to increase both DLR and OLR until the latter returns to its earlier values sufficient to balance absorbed solar radiation. That increase in DLR and OLR is a manifestation of a higher temperature.
My next comment after the one you responded to was that adding CO2 actually cools the atmosphere at first. This is supported in parallel discussions with Alex Harvey and Chris Colose (though we haven’t quite convinced Fred yet). It is counterintuitive. The explanation is that adding CO2 enables the atmosphere to radiate and absorb more efficiently. These opposing effects cause it to warm more by absorbing surface photons better and emitting less to space, but also to cool more by emitting to the surface. The latter turns out to be more important, although the effects are within 10% of each other.
The other way to understand it, and the way I came to it, is that IR in general is a cooling influence in the atmosphere (as it is at the ground), and enhancing it by adding CO2 enhances this cooling effect.
Jim – Chris can speak for himself, but I interpret him as saying that added CO2 increases atmospheric temperature even though with more CO2, there are more IR emissions from within the atmosphere. I haven’t yet seen any mechanism to contradict this when analyzed at the level of each atmospheric layer, but perhaps an alternative will be forthcoming.
Fred, as I posted elsewhere here replying to Alex, more experiments with Modtran have forced me to modify my view slightly. In a tropical atmosphere, instantly doubling CO2 would lead to a net warming effect, while in the US sounding (more like a global average) it results in net cooling. The sign of the immediate change being variable reinforces to me that the driver for further changes is the increased DLR, with the immediate atmospheric temperature change not being part of the explanation, so the rest of the argument holds up.
My next comment after the one you responded to was that adding CO2 actually cools the atmosphere at first. This is supported in parallel discussions with Alex Harvey and Chris Colose (though we haven’t quite convinced Fred yet). It is counterintuitive. The explanation is that adding CO2 enables the atmosphere to radiate and absorb more efficiently. These opposing effects cause it to warm more by absorbing surface photons better and emitting less to space, but also to cool more by emitting to the surface. The latter turns out to be more important, although the effects are within 10% of each other.
Jim, that’s a lovely observation. I can see that it’s true by the following argument. What’s different about the incoming CO2 from the established CO2 is that the former hasn’t yet got into the routine of absorbing and emitting photons, so it’s “bank account” so to speak of vibrational energy is initially empty. It establishes itself by building up to an ongoing nonzero account, which cools the atmosphere.
Is that your argument or do you have a different one? If the former, how long would you say it take for a freshman CO2 molecule to establish itself? If the latter, does your argument estimate more or less cooling than mine?
A more important question for your point might be, if CO2 molecules come from combustion, wouldn’t they enter the atmosphere with more vibrational energy than the established ones rather than less?
The molecules have more vibrational energy, when the gas is hotter as the flue gases usually are. That’s part of the specific heat of CO2.
“If so then we may conclude that almost all the warming of the atmosphere is conveyed to the surface by convection and conduction, and that DLR plays no significant role in global warming. In order for it to go the other way the air skin on the ground would have to be centimeters thick…Put simply, a warmer atmosphere warms the ground by direct contact, with essentially no assistance from DLR.”
Vaughan – That is probably incorrect. Rather, DLR is the predominant mechanism whereby atmospheric warming is conveyed to the surface. At the surface, in the absence of conduction, a discontinuity exists because the air is radiating both up and down while the surface radiates only upward. Thus, if the surface radiates 2W upward in a steady state, the overlying air would have to absorb and radiate 2 W, but since it does this isotropically, its radiation per meter squared is halved and therefore its temperature must be lower by (1/2)^4 via Stefan-Boltzmann. What conduction does is eliminate the discontinuity so as to raise the air temperature at the surface – i.e., the ground heats the air by conduction. This is a change in a direction opposite that of transfer from air to ground and would counteract any air to ground heat transfer.
The KT energy budget and confirming observations of DLR indicate the very large amount of energy absorbed by the land and ocean from the atmosphere. Conduction appears to play a minor role in the opposite direction – heat loss.
Of course, the air is also absorbing IR from above, and in that sense my explanation oversimplifies, but the discontinuity is a valid principle, as is its resolution by ground to air conduction.
Also, I meant the 4th root of 1/2, not the fourth power.
Fred, I believe you’re analyzing the steady state, where it’s clear that a lot of DLR is reaching the ground. The point is that it’s not raising the temperature of the ground in the steady state, it’s just holding it at its present temperature (averaged over say a year, to the extent that makes sense). Hence your analysis is fine, but says nothing about rate of warming. You need to take the derivative of what your looking at with respect to time.
When CO2 increases, both DLR and temperature increase. All this happens extremely slowly, that is, both dF/dt and dT/dt are tiny. The increasing temperature of the surface, dT/dt for the surface, is driven both by dT/dt for the bottom of the atmosphere and dF/dt for DLR. When these last two are both zero the surface eventually equilibrates and their is no further warming of the surface. When one or both is positive the surface warms accordingly. We want to know what dT/dt for the surface is, and we infer it from dT/dt for the bottom of the atmosphere, which we convert using the thermal conductivity of air to conductive dF/dt, and we have radiative dF/dt with no need of such conversion.
Having reduced the rate-of-increase contributions of thermal conduction and radiation to common units of dF/dt in nanowatts/m2/sec, we can compare them directly. My observation was that radiative dF/dt is around 5 in those units while conductive dF/dt might be 250 for a 0.1 mm skin. DLR would then be responsible for about 2% of the rate of warming because conduction would be basically a short circuit by comparison.
Vaughan – It seems to me that you continue to make the same mistake, because you still haven’t come to terms with the fact that conduction at the air/surface interface is from surface to air rather than the reverse. This is due to the discontinuity that would create a substantial temperature drop from surface to air based only on radiative transfer.
When GHGs increase, the increase in DLR will be the predominant mechanism whereby thermal energy is transmitted to the surface. The energy balance shows that conduction plays a much smaller role, but more importantly, in the opposite direction. Increase in air temperature will of course tend to reduce the conductive flow of energy outward from the surface, but the increased DLR will tend to increase the temperature discontinuity and enhance outward conduction. Because of the small overall role of conduction, these changes in the conductive balance outward will be overwhelmed by the increase in absorbed thermal energy from the increased DLR. Some details are given in “Principles of Planetary Climate” on page 392 quantifying the increase in surface/air temperature differences as a function of back radiation.
For all these reasons, your interpretation of the role of conduction vs DLR appears to be untenable, even though it would make sense if the temperature discontinuity did not exist. Your interpretation would also predict that as atmospheric and surface temperatures rise, the conductive heat loss from the surface would decline in absolute (W/m^2) terms rather than rise. I expect that data on this will show the opposite (more conductive heat loss with rising temperatures), but if you have a data source demonstrating reduced conduction, you should cite it.
It also occurs to me that you may be assuming that the DLR increase is exclusively a function of an increase in temperature at the bottom of the atmosphere. However, the increased DLR will come from changes at all levels of the atmosphere, and thus can increase significantly with only minimal temperature change at the bottom. To quantify this would require modeling involving the radiative transfer equations at relevant wavelengths, and is not something that could be done as a back of the envelope exercise. I don’t know the outcome, but it might turn out that the “mean conductive distance” is measured in meters rather than fractions of a millimeter.
It seems to me that you continue to make the same mistake, because you still haven’t come to terms with the fact that conduction at the air/surface interface is from surface to air rather than the reverse.
Fred, you’re still not making the distinction between F and dF/dt. Yes there is a significant net upward flux from the surface to the air, but in my analysis this is constant and therefore contributes nothing to dF/dt at that interface. We’re talking about global warming and you’re describing a situation that has been the case for billions of years with no human intervention.
I don’t think this makes much sense. Increasing DLR will increase the conductive flux outward for the reasons I’ve outlined. Increasing air temperature may operate in the other direction, but the balance change will be small and probably net outward.
As I mentioned in my above comment, the DLR will come from multiple altitudes, and its increase will exceed – perhaps greatly – the increase due to temperature change of air at the surface. The conduction effect will reflect only the latter, while the DLR effect will represent the entire atmosphere.
One further point before we beat this horse to death. Consider the process of response to a radiative imbalance as though it occurred in steps instead of through concurrent mechanisms. Let’s say CO2 increases to the point of a 2 W/m^2 TOA imbalance. At this point, some IR that would ordinarily escape is redirected downward at all atmospheric levels and is absorbed at the surface as an increase in DLR. In our hypothetical stepwise scenario, this has occurred with no change in atmospheric temperature at all, simply because of the redirected energy. Step two consists of atmospheric warming from the increased IR retention.
In the real world, these events are concurrent, but the point is that DLR changes are not due entirely to changes in atmospheric temperature, and can be significant with relatively small temperature changes during the initial stages of an imbalance.
Writing in prose won’t solve this. Without formulas and associated values there is no precision in your comments. Back up what you say with values for each of F, T, dF/dt, and dT/dt for each of DLR and conduction, specifying where, and we can then compare values for these to see where we disagree.
I have only briefly followed the exchange between Fred, Vaughn, and Arthur, so I apologize if I repeat already mentioned things, but to highlight a few points.
— The enhanced greenhouse effect is not directly dependent on the atmosphere becoming a better emitter of DLR to the surface when you add CO2. Think of a scenario where we thicken high cirrus and cirrostratus clouds to an atmosphere optically thick in the boundary layer, or migrate them to a lower pressure so that they are colder. In this case, the cloud is, if anything, emitting weaker DLR and it is unlikely that the DLR will actually make it to the surface, under the assumption that our lower atmosphere is opaque. But such a cloud will invariably increase the greenhouse effect, reducing the OLR and forcing the atmospheric (and surface) temperature to rise.
— The DLR will increase eventually, primarily because T increases (or because it is now holding more water vapor). The tropics fall close to the scenario played out above, since the lower atmosphere is moisture-heavy and IR opaque, and the corresponding surface forcing from direct increases in DLR by making the atmosphere a better emitter is far less than in the higher latitudes (see e.g., Lu and Cai, 2009,Quantifying contributions to polar warming amplification in an idealized coupled general circulation model, Climate Dynamics, particularly Fig. 2).
— Increasing CO2 will eventually cause all the surface fluxes to change, not just the radiative ones. As explicitly pointed out in Miller, 2011 in press (http://pubs.giss.nasa.gov/abs/mi09610i.html) the result is for the TOA forcing to control the surface temperature change and the exchange of the surface fluxes to regulate the ground-lower atmosphere temperature difference.
“Without formulas and associated values there is no precision in your comments.”
There is a good mathematical treatment starting on page 391 of Pierrehumbert’s “Principles of Planetary Climate”. What is surprising in that analysis is the magnitude of the temperature discontinuity between surface and the air in contact with it based on radiative transfer alone. In an atmosphere with significant IR opacity, such as ours, it can exceed 30 deg C. However, in reality, the difference is much smaller, because the difference generated by increased back radiation is countered by significant increases in outward conduction followed by convective and other turbulent temperature changes to eliminate the discontinuity.
Chris, you’re absolutely right that all the surface fluxes changes. Hence you can hold any or all of them responsible, which is my primary point. Comparisons between them showing one dominates another must be done rigorously, but that’s a secondary issue.
Miller knows his stuff. The only issue I’ve ever had with him is details about resonances in Milankovitch cycles, the logic of which is tricky to get right. Outside of paleoclimate I am 100% aligned with him. (And not just as a way of getting invited to Tea Parties.)
Fred, do you feel your quotes from RPH support or weaken my account? Seems to me they support it. The bit about turbulence at the surface is what I had in mind when I said earlier that I was getting out of my depth in estimating the skin, which turbulence should decrease dramatically compared to a smooth breeze. The idea that turbulence will naturally occur as a result of the strong diurnal fluxes creating large temperature discontinuities at the surface does not surprise me.
Vaughan – I believe the RPH treatment renders your interpretation untenable, but if you get a chance to read it, you can make your own judgments on this. The effect of DLR would be to magnify the disparity between surface and air temperature, and create a conductive gradient that is increasingly in the outward direction.
I have to leave the discussion at this point – reluctantly. It has been interesting, and readers should not mistake disagreement here for disagreement about either the GHE or the magnitude of absorbed DLR. It is only about the exact energy transfer mechanism.
The effect of DLR would be to magnify the disparity between surface and air temperature, and create a conductive gradient that is increasingly in the outward direction.
But it’s not the DLR that matters for that purpose, it’s the net radiative flux, which is 390-324 = 66 W/m2 of cooling. This is offset during the day by 168 W/m2 of directly insolation. If the difference 168 – 66 = 98 were constant the surface and air temperature would drift into equilibrium. It is the switching on and off of the insolation at dawn and dusk that creates the disparity and the resulting turbulence on an ongoing basis.
Oops, ignore what I said about R. Miller, whom I don’t believe I know. I somehow mixed him up with Richard Muller. Sounds like I agree with both of them. :)
Vaughan – Insolation is critical, as you suggest, in determining the radiative gap between surface and overlying air. The important point as I see it, is that as GHG concentrations rise, DLR increases and this increased energy is absorbed by the surface as the predominant contributor to the increased heat content and temperature of the ocean and land. Net conductive flux is strongly upward, and so a conductive change serves to reduce heat loss that would otherwise result from the rising temperature, thereby permitting the temperature to reach a higher level. It is not so much the source of the temperature increase as it is a preserver of that increase. DLR is the main source, and as I suggested earlier, a CO2 increase can mediate significant DLR increase even if atmospheric temperature can be kept constant, although increased temperature also contributes to increased DLR.
It’s probably artificial to consider these phenomena as separate entities, because they work together for a final result. If DLR did not exist, a radiative imbalance would be restored to equilibrium by other means, but in our current climate, it is a predominant mechanism.
Interestingly, elsewhere in this thread, Alex Harvey and Jim D have suggested a concept somewhat antithetical to yours. They suggest that CO2 increases will cause atmospheric temperature to decline rather than rise except for the ability of DLR to warm the land and ocean, which in turn warm the atmosphere. I probably don’t agree with the temperature reduction aspect of their argument, but I do think they are correct in stating that DLR can cause a warming effect partially independent of atmospheric warming. This is simply because more CO2 molecules will result in more upwelling photon energy being redirected downward, even at a fixed temperature.
At this point, you must start to plug in numbers to your equations and compare them to observations.
To me, those words mean that your analysis differs from physical reality, aka is unphysical, and so your argument is forfeit.
No, the laws of physics are the same. One of the quantities is changing, thus, you need to start plugging in numbers and compare them to real observations. Pointing your IR gadget in two directions does not substantiate all these assumptions you’re making.
Yes, and even the constancy argument (which I believe is false) doesn’t work. If an increase in downward conduction were to account for a surface temperature increase, then the net flux must change. That should be true whether it is upward or downward to start with. One can’t have inward conductive W/m^2 increasing at a particular rate and outward W/m^2 increasing at the same rate, and still make this the cause of a changing temperature, particularly in a system which dissipates most of a temperature increase via increased radiation. The change in net conductive flux might be small, but it can’t be zero. In reality, I expect it’s in the wrong direction to support Vaughan’s argument – that’s because an increase in DLR will increase the gap between surface temperature and the lower temperature of the overlying air.
One of the quantities is changing, thus, you need to start plugging in numbers and compare them to real observations
Suppose that quantity is Q. If what matters is that Q is changing then the relevant value is not Q but dQ/dt. You need dQ/dt in order to know whether the fact that Q is changing is relevant: the larger dQ/dt is, the more relevant is the fact of changing.
Pointing your IR gadget in two directions does not substantiate all these assumptions you’re making.
Correct. That’s because it only measures F, not dF/dt. My point is that F is relevant only to global warmth. For global warming you need dF/dt for which I have no (immediate) instrument.
You have just admitted that you are using the wrong tool for the job.
In layman’s terms, for the linchpin of your argument, you got nothing.
You’re overlooking that my thermometer was for the benefit of those who doubt the existence of DLR. Where did I imply it had anything to do with my argument, which deals with dF/dt, not with the F that the thermometer measures?
I’m ignoring no such thing.
Granted, you never did imply that was where you were pulling your unsubstantiated assumptions about dF/dt out of. Nor did I imply that you had any basis for your assumptions about dF/dt. What I noted was what you said first. You have no basis whatsoever for your assumptions about dF/dt.
This is an excellent comment and clearly shows Dr. Pratt has quite a deep understanding of the science (more than most who seem to have responded to this article assumed – miscommunication goes many ways around here). Nevertheless, while qualitatively appealing, the discussion is not entirely correct.
That is – there is no way to quantitatively calculate the effect of a change in atmospheric composition (such as doubling CO2), at least for the problem on Earth, without accounting for the changes in DLR explicitly through a radiative transfer calculation. Thinking of it in terms of slowing down escaping photons is treating the problem in essentially a continuum manner, similar to a diffusion problem. That’s fine if radiation is absorbed quickly, in the center of the absorption bands, the problem is then essentially diffusive, and the radiative transfer problem is somewhat like a standard heat conduction problem. And in the “window” regions, where there’s essentially no absorption, you have simply a constant fraction of emission that escapes directly to space, a short-circuit between the surface and the 2K vacuum so again the result is simple. But in the “wings” of the absorption bands, where a given wavelength of radiation might be absorbed just once on the way out, you have to treat the radiative energy exchange as a discrete process linking surface temperature to temperatures all through the atmosphere. There’s no simple analogy I can think of between this radiative transfer situation in the wings of an absorption line and any normal heat transfer problem – it is fundamentally a matter of direct exchange of quantum particles over a very long distance and across large temperature differences, something you rarely see. The math for this is just different from standard heat transfer.
And then – the process of warming itself is a little different from what you describe. If you instantaneously double CO2 in the atmosphere while keeping all else fixed to start, the radiative transfers change in such a way that the largest flux gain is at the surface, with gradually reduced net energy flux changes as you go up through the atmosphere until the net flux change becomes one of *cooling* once you reach the stratosphere (and stratospheric cooling has been observed). This is because, at the start, the surface has not warmed yet, so there is no upward increase in radiation to compensate for the increased DLR. The detailed warming process after an instantaneous doubling would be quite complex, and doesn’t match the simple picture you draw here. Convection would certainly be involved in redistributing the heat – but I don’t think any atmospheric scientist would deny that!
Thanks very much for your thoughtful and insightful comments, Arthur. Let me respond to what I’m hoping will be the easiest to answer. I’ll assume until you say otherwise that your concern is with the second half of my comment at
http://judithcurry.com/2011/08/13/slaying-the-greenhouse-dragon-part-iv/#comment-98462
and that you’re ok with the reasoning up to and including the proposition that warming the atmosphere then also warms the surface, and that the joint warming of everything then raises total radiation until balance is restored. (Or at least Earth warms fast enough to prevent any imbalance from growing indefinitely; there may be some persistent lag as CO2 and temperature continue to rise.) Let me know if not.
If that much is OK then the question becomes, is DLR the main way of converting atmospheric dT/dt to surface dT/dt?
If you instantaneously double CO2 in the atmosphere while keeping all else fixed to start, the radiative transfers change in such a way that the largest flux gain is at the surface, with gradually reduced net energy flux changes as you go up through the atmosphere until the net flux change becomes one of *cooling* once you reach the stratosphere (and stratospheric cooling has been observed).
Quite right, and what I wrote neglected this. However wouldn’t taking it into account increase the ratio of dT/dt to radiative dF/dt at the surface, by virtue of increasing dT/dt there relative to higher up? Conductive dF/dt through the skin is linear in temperature (Fourier’s law of thermal conduction) whence higher dT/dt at the surface implies higher conductive dF/dt there. If conductive dF/dt through the skin is already much greater than radiative dF/dt at the surface with my overly simplistic model, wouldn’t that be even more so in the more accurate model you’re pointing out?
Putting my argument in its simplest terms (so as to make it easier to debug), if the atmosphere is gradually warming then in the absence of DLR this warmth will still eventually reach the surface via convection and conduction. Conversely if conduction doesn’t occur but DLR does, the DLR will warm the surface.
But if both are in effect, which warms it more? Naively DLR would because it “gets there first.” But if the rate of warming is what matters, and if dF/dt is a steady nanowatts/m2/sec over decades, then the bottom of the atmosphere is warming at some equally steady dT/dt in parallel with DLR increasing at dF/dt. By Fourier’s law of thermal conduction we convert dT/dt to conductive dF/dt and then make a direct comparison of conductive and radiative dF/dt to see which is contributing more to the rate of increase of the surface temperature.
Right now it’s late at night and my logic engine is suggesting I sleep on it. Maybe this line of reasoning won’t seem so sensible in the morning, we’ll see.
I do agree with your point (if I understood it) that DLR must be analyzed to get a reasonable distribution of fluxes within the atmosphere as a function of (at least) altitude. But is a distribution really needed if one just wants to show that more CO2 means fewer photons escaping to space and hence a warmer planet. What is the simplest yet rigorous way of demonstrating this?
That is far and away the most sophisticated, most technically literate climate science denial sophistry that I have ever seen!
But it is still just sophistry, sir.
False. You may conclude from your calculations that DLR does not directly warm the surface. You have convincingly argued that the atmosphere’s thermal contact with the ground by conduction and convection are the dominant factors in warming the surface, but you have already conceded that the atmosphere is warmer due to DLR than it would be without DLR, and that means that it is warmer with more carbon dioxide than it would be with a lower concentration of carbon dioxide. So, by your own admission, the conduction and convection that warms the surface has more warmth to transfer to the surface as a direct result of carbon dioxide, and therefore DLR from carbon dioxide plays a pivotal role in global warming.
So now the surface of the Earth, not the air, is over heating due to CO2?
Are we going to see magma puddling, or merely spontaneous combustion of forests and neighborhoods? What about the oceans? How will they react to this run away CO2 heating?
‘settled science’ is operating at about this level:
So now the surface of the Earth, not the air, is over heating due to CO2?
Hunter, get with the program. Or are you working with the same definition of “now” as Don Easterbrook? In his demonstration that medieval warming was warmer than now, Easterbrook tacitly defined “now” to be about a decade after 1896, the date of Svante Arrhenius’s paper “On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground”. Global warming has been about the surface (land and sea) ever since that date. Given how much of the absorbed heat has been going into the ocean, it has to be for any energy budget of the planet that isn’t a travesty (technical term).
So, by your own admission, the conduction and convection that warms the surface has more warmth to transfer to the surface as a direct result of carbon dioxide, and therefore DLR from carbon dioxide plays a pivotal role in global warming.
Are you ok with formally defining “warmth” as temperature T, and more warmth, or just “warming”, as dT/dt, rate of change of T? Without formal definitions of these informal terms it is hard to reason reliably about the underlying physics.
I don’t agree with your “therefore.” More CO2 captures more photons, thereby gaining vibrational energy and raising the temperature of the atmosphere by transferring that energy to other air molecules principally by collision. The warmer atmosphere then warms the surface by rising conduction resulting from rising air temperature as well as by rising DLR. Even though T and DLR may both be substantial, if dT/dt = dF/dt = 0 in the atmosphere then dT/dt = 0 for the surface as well. There can be no warming of the surface without warming of the atmosphere, using the above formal definitions of these informal concepts.
Global warming is not the same thing as global warmth. This distinction is constantly blurred in this and other blogs, thereby causing endless confusion.
My main claim is that it doesn’t matter how the labor of warming the surface is divided between conduction and radiative dF/dT. My less relevant (but possibly interesting) claim is that al scientifically rigorous estimates of that proportion to date show that much more of that labor is performed by conduction than by rising DLR. Perversely perhaps, I love to be proved wrong, and would therefore be very happy to see a rigorous derivation of the opposite conclusion!
the most sophisticated, most technically literate climate science denial sophistry that I have ever seen!
Thank you, but you’re too kind. I’m not denying global warming is taking place, nor that DLR is real and substantial. I’m merely denying the logical necessity of rising DLR, positive dF/dt, in accounting for rising surface temperature, positive dT/dt. Global warming understood as surface warming can be just as well or better explained in terms of rising air temperature at the surface. This denial of the logical necessity of rising DLR has no impact on either the fact of global warming or its extent, it merely fixes what I feel is flawed logic in the proof of global warming.
Unsound proofs of true propositions are common but unjustifiable. They are commonly justified on account of the truth of the proposition, but that reasoning is circular.
Absolutely.
We’re also agreed on how CO2 and other greenhouse gases trap IR emitted FROM THE SURFACE. I think that bit in all capitals is what you’re neglecting in your entire analysis, as well as how the surface actually gets to be warm in the first place.
No doubt about that.
Citation needed. What directly warms the surface? Says who?
We’re also agreed on how CO2 and other greenhouse gases trap IR emitted FROM THE SURFACE. I think that bit in all capitals is what you’re neglecting in your entire analysis, as well as how the surface actually gets to be warm in the first place.
The surface got warm before there were humans. This discussion concerns global warming, which can start from the premise that the surface is at around 280 K or whatever it was in preindustrial times. The surface has been emitting IR for billions of years.
Citation needed. What directly warms the surface? Says who?
Let me get this straight. You’re asking for a citation proving that blowing air over the cooling fins of a CPU will cool it? Reminds me of the Wikipedia editor who asked for a citation for the claim that the human hand has five fingers.
Or did you think that the heat in the fins was being radiated into the air and then rapidly carried away?
I think the rising threw him off. The warmer atmosphere then warms the Earth through increased conduction due to the increased air temperature as well as increased down welling radiation. That may be clearer.
Yes, much clearer. Thank you for putting it so simply.
You can’t understand the point of the question, unless I emphasize the last two words? Fine.
Says who?
What directly warms the surface? Says who?
What I contest is not whether conduction & convection occur. What I contest is whether anybody ever said otherwise.
You have argued that IR is not directly absorbed at the surface, and you have argued that well enough.
I am asking you, who ever said that IR is directly absorbed at the surface?
http://content.imamu.edu.sa/Scholars/it/net/trenbert.pdf
Fasullo & Trenberth don’t say that it is. Granted, page 4 says “Absorbed by Surface” and back radiation is clearly referenced in the text. But nowhere do they actually claim that at the air/surface boundary where you are obsessing, conduction & convection are not the primary modes of heat transport, do they? Does anybody? If not, you are just making a straw man argument. Is this entire argument of yours intended as rebuttal to the shorthand that fits on a diagram?
Obviously, we are not walking around on greenhouse gases. If I thought it was important to know whether back radiation is directly absorbed by solids and liquids on Earth’s surface or whether that heat transfer must be occurring via conduction and convection, I would go look up the line spectra of the relevant substances, starting with silica & liquid water. But if you want to claim that the warming must occur by conduction & convection, not by back radiation, and therefore to claim that such disproves anybody else, you must first cite who has said that back radiation directly warms the surface.
I posit that it is not specifically mentioned because it is not considered interesting to those balancing the global mean energy budget, because as you admitted from the outset, it is irrelevant to the correctness of the climate science consensus. Whether IR radiation or conduction & convection (of heat trapped by CO2, then transferred by collision to O2 & N2) directly warm the surface is not addressed in the literature to my knowledge. It is omitted, and omission is not error, particularly when, as you’ve already admitted, it is irrelevant which is the case.
So the whole case you’re making is based on your own incorrect inference, that somebody ever asserted that the surface directly absorbs IR. Or, it’s the incorrect inference of the climate science deniers on whose behalf you’re arguing. It becomes difficult, when debating the Devil’s Advocate, to know whether your errors are your own, or on behalf of your client.
But nowhere do they actually claim that at the air/surface boundary where you are obsessing, conduction & convection are not the primary modes of heat transport, do they? Does anybody?
Well, I don’t know whether you consider the IPCC “anybody”, but they say pretty clearly in Chapter 1 of AR4:
“To balance the absorbed incoming [solar] energy, the Earth must, on average, radiate the same amount of energy back to space. Because the Earth is much colder than the Sun, it radiates at much longer wavelengths, primarily in the infrared part of the spectrum (see Figure 1). Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and reradiated back to Earth. This is called the greenhouse effect.”
I think a lot of people have taken that last “This” to include the last step, in which the absorbed thermal radiation is reradiated back to Earth. Absent mention of any other transport mechanism, the IPCC seems to be claiming that the Earth is warmed radiatively, namely by reradiation. Are you somehow reading this differently from me? And I suspect from a lot of other people?
Vaughan Pratt
See my post responding to your comments on Miskilczi’s virial calculation.
No, that’s still just your inference. It’s not a crazy inference from that text, but it is still just an inference and I didn’t ask you for your inference, and I know I made that perfectly clear.
Like all climate science deniers, the best you can do is disprove things nobody ever said. As I said, yours is the most impressive bit of such sophistry I have ever seen, but it is still just sophistry. It just takes a bit more work to identify your straw man.
What you have claimed to be untrue, is also never asserted. It may (or may not) be implied, but it is never said because, as you admit from the start, it is irrelevant. Whether back radiation warms the surface, or whether back radiation warms the air which warms the surface by conduction and convection, in either case back radiation warms the Earth. That is Settled Science.
PS
re: “Thank you, but you’re too kind.”
Any time.
Vaughan Pratt
Two words: Thermal capacity. Look it up.
Two words: Thermal capacity. Look it up
If you’re worried that it takes 5 exajoules to add a degree to the atmosphere, that’s very little in the grand scheme of things, as the global energy budget literature points out from time to time. It’s about equivalent to the top three meters of the ocean. Global warming is currently about 1.6 millidegrees a month adding 8 petajoules to the atmosphere. Please show with working that a mere 8 petajoules is so much that a month of global warming can’t add that to the atmosphere.
Oops, scale all that up by 1000, I was calling 10^18 kJ an exajoule but overlooked the k so that’s 10^21 J hence a zettajoule. 8 petajoules should have been 8 exajoules.
No. You were saying that the atmosphere warms the surface by conduction. The massive difference in thermal capacity alone should tell you that this doesn’t happen. And then there’s the fact that warm air rises, and is displaced by colder air cooled by the ground beneath.
Actually the thermal capacity of the atmosphere is not terribly different from that of the portion of the surface capable of sensing diurnal fluctuation.
Global warming on the other hand is by a vastly smaller amount than the diurnal fluctuation at the surface, as well as on a vastly longer time scale, so there is nothing unreasonable in the idea that the global warming of the atmosphere could be transmitted to a volume of surface with a thermal capacity many times that of the atmosphere.
Luckily it’s irrelevant to the question of the respective values of dF/dt for respectively radiation and conduction at the surface, which both face the same obstacle of getting that heat below the top millimeter of the surface. Hence I don’t need to compute how deep global warming can go. But if you compute it I’d be interested in your answer, especially if it proves me wrong.
I’m afraid I’m not at all sure that I follow what you’re saying – perhaps it’s just me suffering the effects of the weekend.
Do you have something akin to an example?
Let’s start with the most important point first. I claim that thermal capacity of what’s below the surface (if that’s what you’re referring to) is irrelevant to the question of whether the surface is being heated by the atmosphere conductively, radiatively, or both. I would have thought this was clear, but if you doubt it I’ll be happy to take a shot at arguing it.
It it’s not what you’re referring to then you might like to expand on your point about thermal capacity.
Vaughan – wikipedia has US annual energy consumption at 105 exajoules in 2005.
Are you saying (with the correction below) that 1.6 millidegrees Centigrade warming of the atmoshpere would be expected for an 8 exajoule input based on atmospheric heat capacity? And that this is the average monthly global warming we are seeing?
If so, do you have any comment on the fact that the US average monthly energy consumption (2005) was 105/12= 8.75 exajoules?
Apologies if I have misunderstood – I haven’t followed the whole thread.
If so, do you have any comment on the fact that the US average monthly energy consumption (2005) was 105/12= 8.75 exajoules?
CO2 as an agent of global warming is something like the catalytic converter in your car exhaust. The energy obtained from fuel in the process of burning it to produce CO2 has little relationship to the heat that CO2 prevents from leaving the Earth.
One can demonstrate this quantitatively, but a qualitative way of seeing it is that the energy obtained in return for emitting a given mass m of CO2 is in proportion to m, whereas the energy that mass is responsible for preventing from escaping from Earth is in proportion to mt where t is its residence time in the atmosphere. It would be remarkable if the residence time turned out to have any bearing on the energy derived from burning fuel to produce CO2.
The similarity of the two numbers you point out would seem to indicate that the forcing induced by a given amount of CO2 is roughly equal to the energy obtained in the course of burning the fuel that produced this CO2, multiplied by the residence time in months. If so that’s quite a convenient coincidence, thanks for noticing it!
Thanks Vaughan but I’m still curious about the impact on atmospheric temperature of the 8.75exajoules per month liberated from fossil (and nuclear) power generation.
Had I correctly interpreted your numbers on atmoshperic heat capacity? If so, doesn’t this local heat addition equate to a monthly temperature rise of a similar magnitude to that which we are observing?
I’ve done a “ctrl-f” on the thread for “residence” and it only comes up in your comment above. If there are other comments which I should read please point them out. Thanks.
The numbers for the heat released are not hard to convert to W/m^2 and I seem to recall that, on a global basis, they come out to be about 0.02 W/m^2. This is to be compared to about 4 W/m^2 for doubling CO2 (and ~2 W/m^2 for increasing CO2 from the pre-industrial levels to the current levels). So, in other words, it is pretty insignificant. Of course, there is a lot of local variation and it may be true that on a local scale they can sometimes be more significant. (Surely, we do know, for example, that a power plant can have significant effects on the temperature of the stream that it uses for cooling.)
Thanks Joel below – that number rings a bell from my sums on a global basis, but I’d still like to know what happens to the 8exajoules/month of heat US energy consumption adds at approx surface height level. If I’ve understood Vaughan correctly (no guarantee!) he seems to be saying this would be enough to generate an increase in air temp. equivalent to observation?
Residence time didn’t come up before. You can read about it on the web, e.g. at
http://www.princeton.edu/~lam/TauL1b.pdf
which gives a range of 70-400 years as a plausible range of residence times.
Meanwhile I just realized that your monthly figure of 8.75 exajoules of energy consumption was for the US. Using a figure of 480 exajoules for annual global energy consumption, 8 exajoules is consumed worldwide every 6 days. Rounding that up to a week for simplicity, the ratio I referred to should have been expressed in weeks of residence time, not months.
However the discussion with Peter371 that you jumped into was for heat content of the atmosphere alone associated with a rise of 2 degrees/century. This is useless as a measure of total heat of the planet attributable to global warming since only a very small fraction of that heat ends up in the atmosphere.
In the 2009 paper Earth’s Global Energy Budget, Trenberth, Fasullo, and Kiehl estimate the top-of-atmosphere (TOA) energy imbalance at some 500 terawatts. What exactly happens to the difference is not clear, but less than a percent of it ends up warming the atmosphere, say around 2-3 terawatts. At that rate the above ratio should be in neither months nor weeks but hours of residence time!
By comparison the above figure of 480 exajoules per year represents 15 terawatts of world-wide power consumption. So if we take TOA imbalance as a measure of global warming, this shows that global energy consumption is a mere 3% of global warming, in case that addresses what you were asking. Hopefully that turns out to be a more reliable number than anything we might base on CO2 residence time.
But don’t trust my numbers, which for one thing haven’t been vetted by anyone and for another are almost sure to have calculation errors, unwarranted assumptions, misunderstandings of the literature, etc. etc. Google Trenberth on energy, he has a number of papers, some with Kiehl and/or Fasullo, that have a lot of numbers of the kind you’re like to be interested in and that are likely to be a lot more reliable than much of what you’ll read on this blog.
Thanks again Vaughan, I’ll continue looking into it. Apologies for jumping in – your specific heat comment caught my eye.
Vaughan Pratt, 8/14/11, 7:18 pm, Vaughan Pratt
The residence time of CO2 in the atmosphere is taught in 11th year public school physics as the leaky bucket problem. IPCC’s formula in its TAR and AR4 glossaries are correct, but, alas, used nowhere in those IPCC Reports. It’s 1.5 years if you include IPCC’s leaf water, but if you ignore leaf water as IPCC does, it’s 3.5 years.
Jeff – Wow, that time keeps getting shorter and shorter! You do know that there is a difference between the residence time of a single molecule of CO2 in the atmosphere and the decay of a perturbation in the atmosphere? Willis Eschenbach does. You’re really hard-core on denying the science, aren’t you?
Joel Shore, 8/15/11, 4:01 pm, Vaughan Pratt IV
Residence time is not getting shorter. It’s staying the same.
We’ve had this argument on WUWT, where you ganged up with Eschenbach to write, as you like to call it, nonsense. (If I created a spam filter to block Joel Shore’s posts with the word “nonsense”, my email flux might be halved.) Why you didn’t bother to quote your own, joint blather is explained after the blather:
Jeff: Willis’s criticism is exactly right and what you are saying is confused and incorrect. The mean lifetime of a CO2 molecule in the atmosphere is short because of the large exchanges that occur between the atmosphere, the biosphere + soils, and the mixed layer of the ocean. However, the decay time for a pulse of CO2 such as by the burning of fossil fuels is governed by the much slower rate at which CO2 can be removed from these reservoirs into the deep ocean. So, what happens when you add in some new CO2 from burning of fossil fuels is that it rapidly partitions itself between the atmosphere, biosphere + soils, and the mixed layer…and now all three of these reservoirs have an elevated level of CO2. And, the decay of this elevated level is very slow. Bold added, Joel Shore, WUWT, 6/12/10, 7:59 pm.
Residence time is defined, and precisely by an equation. None of this talk about slow uptake applies to the formula. The uptake by the ocean from the atmosphere is about 92 GtC/yr for all species of CO2. That is the rate of depletion of CO2 from the 760 or so GtC in the atmospheric reservoir; it is the number to use in the leaky bucket formula along with about 120 GtC/yr to terrestrial sinks, plus another 150 to 270 GtC/yr for leaf water unless you want to repeat IPCC’s erroneous omission. 760/(92 + 120) = 3.6 years; 760/(92 + 120 + 270) = 1.6 years. The notion that the uptake is slower as IPCC claims for ACO2 (about 2.2 GtC/yr) violates physics on at least five counts.
(1) No mechanism exists by which the ocean can distinguish between ACO2 and nCO2, which are different mixes of 12CO2:13CO2:14CO2, and no absorption coefficients can be assigned to create a bottleneck just for ACO2.
(2) The surface ocean is not only not in equilibrium to make the equilibrium chemical equations applicable, but it is never in such equilibrium, which is the bottleneck conjecture.
(3) Dissolution of CO2 in water is instantaneous on climate time scales.
(4) That Henry’s coefficients might depend on sea water pH is novel science, and even if true, far down in the noise of any measurements. No such measurement has ever been made. They depend on pressure, temperature, and salinity, two tied for first order effects, and the other a distant third.
(5) When IPCC climatologists tried to measure the bottleneck, called by the previously defunct name the Revelle Buffer, they measured ordinary, temperature dependent solubility according to Henry’s Law. IPCC removed that analysis and suppressed it so as not to confuse the reader.
Residence time is another bulk parameter. The lifetime of a single molecule has no meaning, and consequently is unmeasurable. That fiction does not appear in the formula. The decay time of a slug of CO2 above a solvent is the information that yields the average life time of a molecule.
We do recognize that you need ACO2 to accumulate in the atmosphere in order for the AGW model to even have a remote chance, so do continue to fantasize about the bottleneck.
Jeff: No system is ever in equilibrium. It is an ideality that is never actually obtained. Therefore, fundamentally, one can never define a temperature of anything. And, yet, we do so.
The fact is that the atmosphere, the mixed layer of the ocean, and the biosphere constitute a subsystem that exchanges CO2 very rapidly between each other but only slowly with the deep ocean. As a result of this separation of timescales, a new slug of CO2 introduced into the atmosphere will rapidly partition itself between the different reservoirs of the subsystem but then the decay of this perturbation from this subsystem is governed by the much slower rate. All these things about the ocean being unable to distinguish between anthropogenic CO2 and other CO2 are a red herring. The important distinction is between CO2 that is just sloshing around between the three different reservoirs vs CO2 that is released from another source.
There are nice analogies with fountains and so forth, but I am too tired dealing with all the sophistry in this thread to write that down in more detail.
Henry’s law applies directly to the solubility of CO2 as dissolved CO2 molecules and non-dissociated H2CO3 molecules. Henry’s constant defined in that way depends only on temperature, not on the composition of the seawater.
When the water is not strongly enough acidic, H2CO3 dissociates to a major part to HCO3- and CO3- – ions and H+ ions. The ratio of H2CO3, HCO3- and CO3- – depends on pH and the dependence is strong, when pH is well above 7, i.e. the water is basic. With the pH of seawater around 8.1 the amount of HCO3- is roughly 100 times that of CO2 and H2CO3, for neutral water (pH = 7) the ratio is roughly 10. Thus the solubility including HCO3- and CO3- – is really strongly dependent on pH in this range and even more strongly for pH > 8. (The amount of CO3- – depends even more strongly on pH, but is relatively small still at pH = 8.1.) When CO2 is dissolved in pure water like in rain drops without extra acidification the pH = 5.5 – 6.0 is clearly on the acidic side. Under those conditions the share of HCO3- is small and CO3- – negligible.
The ratios are fixed for fixed pH. Thus Henry’s law remains valid for fixed pH. The Revell factor is 1.0 in that case. The larger values of the Revell factor are based on the fact that additional CO2 raises pH and lowers the ratio HCO3-/CO2. How much additional CO2 affects pH depends on the chemical composition of seawater. The largest values are obtained, when carbonates are the only buffering component and all other ions are of the type that remain as ions over a wide range of pH (e.g. Cl- and Na+). The Revell factor is lower, if there are other buffering components than carbonate and bicarbonate ions, but the share of other buffering components is not large in oceans. Therefore the Revell factor is rather large, of the order of 10, but varies from one part of the oceans to another.
Well, that’s a change, for me to be preferring Jeff Glassman’s side over Joel Shore’s.
Joel, the “leaky bucket” argument as I understand it has nothing to do with individual molecules. If we’re adding 9 GtC a year to the atmosphere but only 55% of it stays there, then I would interpret the other 45% to be “leaking” into the land and ocean. The identities of the molecules is irrelevant.
You seem to be assuming that if we stop emitting, the leaking stops instantly. My understanding of how leaky buckets work is that if you’re adding water faster than it leaks, the bucket gradually fills up. But if you stop the filling the leaking doesn’t stop, though it slows down as the bucket empties.
In the case of the atmosphere, “empty” should correspond to the preindustrial level of CO2. Since the leaking is currently running at around 4 GtC a year, if we shut off CO2 then the atmosphere should drain starting at that rate and gradually slowing as it approaches the preindustrial level.
Since the carbon cycle is a lot more complex than a leaky bucket, some flows may well decrease faster than others. In particular if we’ve inadvertently encouraged weeds to gobble down CO2 faster than they used to, they may not see a need to stop doing so at the preindustrial level.
If you have a technical objection to the leaky bucket model (as distinct from the “everyone knows the residence time of CO2 is many decades” argument) I’d be very interested in understanding your objection.
Vaughan,
You probably want to read through the CO2 residence time thread and the various references (e.g., to David Archer’s work that have been brought up there). The short answer to why the “leaky bucket” picture is not correct: Let’s take first the mixed layer of the ocean. What happens when you add a slug of CO2 to the atmosphere is that the partial pressure of CO2 in the atmosphere increases. This upsets the equilibrium between the ocean and atmosphere and drives an increase in the CO2 in the ocean mixed layer until the equilibrium is restored. The timescale for this, however, is pretty fast (on the order of a months to a few years at most), so what you then have is an overall higher partial pressure both in the atmosphere and the ocean. [Eventually, the CO2 will get mixed down to the deep ocean but this is a quite slow process.]
For the case of the biosphere: What an additional slug of CO2 does is increase the amount of biomass that can be supported, so again some of the CO2 partitions into the biosphere but it doesn’t just keep increasing endlessly.
Joel,
“For the case of the biosphere: What an additional slug of CO2 does is increase the amount of biomass that can be supported, so again some of the CO2 partitions into the biosphere but it doesn’t just keep increasing endlessly.”
It doesn’t need to keep increasing endlessly, just to the end of our carbon based fuel availability. Research shows that the nitrogen fixation that was thought to be a limit isn’t. Apparently the microbes and other little dickens increase nitrogen fixing with increased growth of many plants. Natural processes will reclaim huge areas of deserts under higher CO2 levels. If we can just keep pumping the CO2…
http://www.co2science.org/subject/n/summaries/nfixherbaceous.php
(10 different papers referenced)
kuhnkat,
Your should first be aware that CO2Science is hardly an unbiased look at the literature.
However, regardless of that, you are addressing a different question than I am talking about: You are addressing the question of whether or not sinks will eventually saturate as we continue to increase CO2 levels. That is, if you are right, what it means is that about half of the CO2 that we emit will continue to partition into the oceans and biosphere. If you are wrong, that fraction may go down in time.
But, even if you are right, that does not challenge my point, which is that what is occurring is such a partitioning and not a “leaky bucket” scenario as Vaughan has proposed.
Joel,
did you at least look at the abstracts of the 10 papers they quoted in the article?? Yes, they are biased just like Pierre Humbert is biased about ice cores and CO2. We have to look at it all and make up our own minds.
Again, it does not need to increase endlessly unless you believe we will increase population endlessly (we seem to be tapering off), hydrocarbons are abiotic (unknown), and we will NOT find better sources of energy in the next 100 years (unlikely as thorium is already available).
Joel,
“But, even if you are right, that does not challenge my point, which is that what is occurring is such a partitioning and not a “leaky bucket” scenario as Vaughan has proposed”
MY bucket has more than one hole in it.
kuhnkat: Ray Pierrehumbert is a very well-respected scientist in the field. Those who publish CO2 Science are not. Even if they didn’t spin those particular articles too badly, they may have omitted articles that don’t agree with their favored point-of-view. It puzzles me why the same people who would likely scream bloody murder if we linked to Greenpeace and Sierra Club for our scientific reviews are so comfortable with reviews carried out by people with very clear advocacy views on the other side.
However, the most important point is even if you are right and the sinks don’t saturate with increasing CO2 levels, that doesn’t address the issue that Vaughan and I are talking about…i.e., it is irrelevant. It is a different issue.
Joel,
y’all are funny. You claim that CO2 site only presents one side of the argument. Uh, well, I probably shouldn’t bring it up, but, y’know, those IPCC reports y’all are so fond of don’t exactly play sceptic either!! They are the epitome of biased Science complete with their own Cult sections filled mostly with NON-PEER Reviewed papers from EnviroWhackjobs. I won’t bother going into the rest of the argument of gatekeeping and blog sites that restrict posters… I do believe the CO2 site actually references peer reviewed papers that are so important to you?? In fact, it is run by SCIENTISTS who actually have PUBLISHED ORIGINAL PEER REVIEWED PAPERS. That was even BEFORE they started their blog. Interesting that anyone who has a different take on the science becomes marginalized in so many ways by you believers.
But enough of the usual whining. You claim my point is not apropos to the argument. In that case, why did you make the point that the reservoir was not infinite if it wasn’t appropriate to your argument? Just an arm wave trying to get some traction?
kuhnkat
Of course Joel can give you an unbiased lead to a”well respected scientist”
Read what another well respected scientist thinks!
pielkeclimatesci.wordpress.com/…/a-response-to-ray-pierrehumbert’… – Cached
kuhnkat
Previous link failed try this.
http://pielkeclimatesci.wordpress.com/2008/05/22/a-response-to-ray-pierrehumbert%E2%80%99s-real-climate-post-of-may-21-2008-by-roy-spencer/
Bryan,
I’ve read some of Ray Pierrehumbert, Jaworowski, Segalstad, and Velikovsky. Old Ray tends to disagree with the other three about the useability of ice core data so he is the odd man out!! 8>)
Did you mean to direct me to this:
“Ray is quite simply wrong — and the reviewers of our paper (Piers Forster and Isaac Held) agree with me. It matters a great deal whether radiative fluctuations are the result of feedback on surface temperature, versus the myriad other variables that control cloudiness. Piers Forster was honest enough to admit that their neglect of the internal variability term in Eq. 3 of “The Climate Sensitivity and its Components Diagnosed from Earth Radiation Budget Data” (Forster and Gregory, J. Climate, 2006) was incorrect, and that it indeed can not be neglected in feedback diagnosis efforts using observational data. He also stated that the climate modeling community needs to be made aware of this.”
http://pielkeclimatesci.wordpress.com/2008/05/22/a-response-to-ray-pierrehumbert%e2%80%99s-real-climate-post-of-may-21-2008-by-roy-spencer/
and
http://pielkeclimatesci.wordpress.com/2008/05/23/follow-up-to-the-response-to-ray-pierrehumberts-real-climate-post-by-roy-spencer/
Yes, in a group consisting of 3 crackpots and one serious scientist, Ray is most assuredly the odd man out!
There is no comparison between the CO2science site and the IPCC reports, particularly the WG1 (Scientific Basis) part of the IPCC reports.
What I said was: “For the case of the biosphere: What an additional slug of CO2 does is increase the amount of biomass that can be supported, so again some of the CO2 partitions into the biosphere but it doesn’t just keep increasing endlessly.” That was a statement about what happens when CO2 increases by a certain amount and then stops. You are now asking a different question, which is whether if CO2 continues to increase, will the amount of biomass that can be supported continue to
increase with it or will it start to level off at some point?
Do you see how this is a different question?