by Judith Curry
The word “doubt” has a bad connotation in the climate debate owing to the merchants of doubt meme. Richard Feynman puts the word “doubt” into the appropriate perspective in the context of science:
When a scientist doesn’t know the answer to a problem, he is ignorant. When he has a hunch as to what the result is, he is uncertain. And when he is pretty damn sure of what the result is going to be, he is still in some doubt. We have found it of paramount importance that in order to progress, we must recognize our ignorance and leave room for doubt. Scientific knowledge is a body of statements of varying degrees of certainty — some most unsure, some nearly sure, but none absolutely certain.
I became outspoken on the subject of uncertainty following the release of the CRU emails. I was hardly the first “mainstream” climate scientist to emphasize uncertainty. Steve Schneider has been generally regarded as the IPCC’s “uncertainty cop.” However Steve Schneider’s vision of climate uncertainty was that of statistical uncertainty, that could be managed in a subjective Bayesian approach using the judgment of experts.
My vision of climate uncertainty includes greater levels of uncertainty, including scenario uncertainty and ignorance. In the broader context of science and the philosophy of science, my view of uncertainty is not unusual at all. However, climate scientists have clung to Steve Schneider’s vision in an ever tightening spiral of reducing uncertainty and increasing confidence levels. I can only hope that my writings on this subject are influencing climate scientists. In any event, it seems that the science journalists are paying attention to the issue of uncertainty.
A twist on climate change uncertainty and risk
Keith Kloor at Collide-a-Scape spotted this essay by Maggie Koerth-Baker, a freelance science journalist. She uses the tornado-climate link as an example. Some excerpts from this essay:
I have a slightly different perspective [ from Bill McKibben]. What we have here is not a failure to communicate and accept the obvious effects of climate change. Instead, it’s a failure to communicate and accept a critical point of how science works, without which scientific literacy is reduced to mere talking points. This is about nuance and uncertainty, and if the American public doesn’t get those things, then we’ll never get climate change.
When scientists study climate they aren’t really studying just one thing. Climate is a complex system, involving multiple natural subsystems and many variables—both “natural” and man-made—that can alter the way those systems work. This is such a complicated subject that we really only developed the computer processing power necessary to start making any sense of it in the mid 1970s. What scientists have learned since then is vitally important stuff. The Earth, as a whole, is warming as humans pump more and more greenhouse gases into the atmosphere. And those rising global temperatures, and rising carbon dioxide concentrations, will affect our lives in a variety of strange, and often surprising, ways. This is the science that should be influencing the way we plan for the future. But it’s not. Not really. And I think the reason why has a lot to do with how science is taught to the vast majority of Americans, the people whose science education really ends along with the end of high school.
In this country, we teach kids that science is a collection of hard facts. We teach them that scientists come up with a hypothesis—an idea that might explain some aspect of how the world works. Scientists then test their hypotheses and find out whether it’s correct or not. If it’s correct, then it becomes something that children must memorize. That story is true. But it’s also vastly oversimplified. It gives people the impression that every scientific question can be answered with “yes” or “no.” And if it can’t, then the real answer is probably “no.”
That perspective might work okay when you’re sitting in a high school science lab, studying the digestive system of a fetal pig. But it doesn’t work as well in the real world. And it leaves people completely unprepared to understand something like climate change, and how we assess the risks associated with it.
That’s because all risk—and especially the risks associated with complex systems like climate—come with uncertainty. To a person whose knowledge of science comes from that simplified story we tell school kids, “uncertainty” sounds like saying you’re wrong without having to say that you’re wrong. But that’s not the case. Instead, “uncertainty” is about complexity and randomness, it’s about probability, and it’s about how you attribute the cause of one effect that is really likely to have multiple causes.
This is scientific uncertainty—where the things we know and the things we don’t know collide, and we are left to figure out how to use what we have to make decisions anyway. That process is so confusing that researchers like Gerd Gigerenzer, director of the Max Planck Institute for Human Development in Berlin, actually make their careers studying the psychology behind it. Gigerenzer will be speaking as part of the World Science Festival panel on The Illusion of Certainty: Risk, Probability, and Chance. It’s an important panel. One that gets to the heart of what scientific literacy is all about.
If we want people to understand science, we can’t just give them facts to memorize. Scientific literacy isn’t about being able to win a game of quiz bowl. It’s about understanding how science works, and how science can be used to guide human decision-making. It’s about knowing that we don’t have all the answers. But it’s also about knowing that “we don’t have all the answers” isn’t the same thing as “we don’t know anything.” If we pump people full of facts, but don’t teach them about uncertainty, then we can’t be surprised when they dismiss anything that isn’t 100% certain.
The future of human life depends on how we respond to the risks of climate change. How we respond to those risks depends on how well the general public understands the messy world of real science.
On not being certain about uncertainty
Chris Mooney at the discover magazine blog has written an article with the title “On not being certaint about uncertainty: why you can’t downplay global warming.” Some excerpts:
The scenarios with the most catastrophic outcomes of global warming are low probability outcomes — a fact that explains why the world’s governments in practice treat reducing CO2 emissions as a low priority, despite paying lip service to it….
In one sense, this is obviously true. In another sense, it’s completely off base.
First, uncertainty cuts both ways, so it makes no sense to be confident that change will be on the low end. This is something about which Kerry Emanuel recently testified:
In soliciting advice, we should be highly skeptical of any expert who claims to be certain of the outcome. I include especially those scientists who express great confidence that the outcome will be benign; the evidence before us simply does not warrant such confidence.
But more generally, you can really only make Lind’s argument if 1) you’re paying enough attention to global warming to understand that there’s a real scientific consensus that it’s happening, but 2) you’re not paying enough attention to realize what global warming really means for Planet Earth.
It’s really that simple. We don’t know the timeline, but if we don’t stop it, we know the eventual outcome–and it is intolerable and unacceptable on any timeline. And that’s why any attempt to minimize worry about global warming by citing “uncertainty” about the projections just doesn’t make sense.
This conclusion brings to mind this quote from Through the Looking Glass:
“If it was so, it might be, and if it were so, it would be; but as it isn’t it ain’t. That’s logic! “
Why ethics requires acknowledging links between tornadoes and climate change in spite of uncertainties
Now for something really “different”, check out this essay by Professor Donald Brown of Penn State University. His punch line:
Because scientists are expected to produce scientific knowledge that can be applied to public policy questions, they must be able to describe threats that are not fully proven. From the standpoint of public policy, therefore, scientists should not deny that climate change creates risks of increased damage from tornadoes. A claim that there is no link between climate change and tornadoes is misleading. If someone is concerned about whether to adopt policies reducing the threat of climate change they need to know whether climate change creates risks of damage from tornadoes even if there are open questions about what happens to tornado frequency and intensity in a warming world.
In other words, when science is applied to public policy where there is reasonable basis that some human activity is dangerous, science has an important role in communicating any scientifically plausible dangerous risks-not just proven facts.
As long as anyone is asking the question of whether there is a link between climate change and tornado damage because they want to know whether there is reason to limit greenhouse gas emissions, it is therefore ethically problematic to say there is no link
However, it is also ethically required to acknowledge that increased tornado damage and frequency are not yet proven. When talking about these risks it is important to acknowledge that there is also scientific basis for doubt about increased tornado and frequency in a warming world. However, if this said, it is also ethically important to acknowledge that increased damage from other kinds of storms is virtually certain as the planet warms. Furthermore, it is ethically important to acknowledge that tornadoes will appear in places that they would not likely occur in the absence of global warming even if tornado frequency and intensity decrease because a changing climate is already affecting tornado propagation.
I’m speechless, I don’t even know what to say regarding this one.
ignoranceanduncertainty.wordpress.com
Yes, there is a blog that I just spotted with the name ‘ignorance and uncertainty’ (I’m adding it to the blog roll, this is a superb blog). The current post is entitled “Communicating about uncertainty in climate change Part I.” The post is written by Robert Smithson (I can’t figure out who he is by googling, the name is too common and there is no “about” info on the blog.) Some excerpts:
I’ll focus on the issues around probability expressions in a subsequent post, but in this one I want to address the issue of communicating “uncertainty” in a broader sense.
Why does it matter? First, the public needs to know that climate change science actually has uncertainties. Otherwise, they could be misled into believing either that scientists have all the answers or suffer from unwarranted dogmatism. Likewise, policy makers, decision makers and planners need to know the magnitudes (where possible) and directions of these uncertainties. Thus, the IPCC is to be commended for bringing uncertainties to the fore its 2007 report, and for attempting to establish standards for communicating them.
Second, the public needs to know what kinds uncertainties are in the mix. This concern sits at the foundation of the first and second recommendations of the Budescu paper. Their first suggestion is to differentiate between the ambiguous or vague description of an event and the likelihood of its occurrence. The example the authors give is “It is very unlikely that the meridonial overturning circulation will undergo a large abrupttransition during the 21st century” (emphasis added). The first italicized phrase expresses probabilistic uncertainty whereas the second embodies a vague description. People may have different interpretations of both phrases. They might disagree on what range of probabilities is referred to by “very likely” or on what is meant by a “large abrupt” change. Somewhat more worryingly, they might agree on how likely the “large abrupt” change is while failing to realize that they have different interpretations of that change in mind.
The crucial point here is that probability and vagueness are distinct kinds of uncertainty (see, e.g., Smithson, 1989). While the IPCC 2007 report is consistently explicit regarding probabilistic expressions, it only intermittently attends to matters of vagueness. For example, in the statement “It is likely that heat waves have become more frequent over most land areas” (IPCC 2007, pg. 30) the term “heat waves” remains undefined and the time-span is unspecified. In contrast, just below that statement is this one: “It is likely that the incidence of extreme high sea level3 has increased at a broad range of sites worldwide since 1975.” Footnote 3 then goes on to clarify “extreme high sea level” by the following: “Excluding tsunamis, which are not due to climate change. Extreme high sea level depends on average sea level and on regional weather systems. It is defined here as the highest 1% of hourly values of observed sea level at a station for a given reference period.”
The Budescu paper’s second recommendation is to specify the sources of uncertainty, such as whether these arise from disagreement among specialists, absence of data, or imprecise data. Distinguishing between uncertainty arising from disagreement and uncertainty arising from an imprecise but consensual assessment is especially important. In my experience, the former often is presented as if it is the latter. An interval for near-term ocean level increases of 0.2 to 0.8 metres might be the consensus among experts, but it could also represent two opposing camps, one estimating 0.2 metres and the other 0.8.
The IPCC guidelines for other kinds of expert assessments do not explicitly refer to disagreement: “Where uncertainty is assessed more quantitatively using expert judgement of the correctness of underlying data, models or analyses, then the following scale of confidence levels is used to express the assessed chance of a finding being correct: very high confidence at least 9 out of 10; high confidence about 8 out of 10; medium confidence about 5 out of 10; low confidence about 2 out of 10; and very low confidence less than 1 out of 10.”
There are understandable motives for concealing or disguising some kinds of uncertainty, especially those that could be used by opponents to bolster their own positions. Chief among these is uncertainty arising from conflict. In a series of experiments Smithson (1999) demonstrated that people regard precise but disagreeing risk messages as more troubling than informatively equivalent imprecise but agreeing messages. Moreover, they regard the message sources as less credible and less trustworthy in the first case than in the second. In short, conflict is a worse kind of uncertainty than ambiguity or vagueness. Smithson (1999) labeled this phenomenon “conflict aversion.” Cabantous (2007) confirmed and extended those results by demonstrating that insurers would charge a higher premium for insurance against mishaps whose risk information was conflictive than if the risk information was merely ambiguous.
Conflict aversion creates a genuine communications dilemma for disagreeing experts. On the one hand, public revelation of their disagreement can result in a loss of credibility or trust in experts on all sides of the dispute. Laypeople have an intuitive heuristic that if the evidence for any hypothesis is uncertain, then equally able experts should have considered the same evidence and agreed that the truth-status of that hypothesis is uncertain. . . On the other hand, concealing disagreements runs the risk of future public disclosure and an even greater erosion of trust (lying experts are regarded as worse than disagreeing ones). The problem of how to communicate uncertainties arising from disagreement and vagueness simultaneouslyand distinguishably has yet to be solved.
Dr. Curry
I think it is Michael Smithson
Michael Smithson is a Professor in the Psychology Department at The Australian National University. Has a couple of books also.
Jeff,
you’re right, it’s Michael Smithson, see
http://www.bestthinking.com/thinkers/science/social_sciences/psychology/michael-smithson?tab=blog&blogpostid=10700
By her writings, Ms. Maggie Korth-Baker is a quintessential example of the US science education she decries and the journalism of tabloid news. She incorporates her belief system, stating it as fact, into the exposition on risk and uncertainty in complex systems. I shake may head in anguish. I agree that Steve Schnieders’s Bayesian analysis of uncertainty requires “experts” whom I have previously characterized as pools of willing yes-men. I presume that is why pal-review has a hard time with uncertainty. Donald Brown of Penn State University sums up the Teams’ current thinking on the incorporation of uncertainty into the science paradigm of Climate Change science. Agast is all I can say. And Robert Smithson lapses into issues of communicating Climate Change uncertainty. For those who seem to have difficulty in communicating, the least one should do is either speak less or not at all. I am mildly interested in what Dr/Mr Smithson might do with probability expressions but alas that is for yet another time. I do wish more people could live their lives with uncertainty instead of insisting upon well deliniated boundaries.
Your own degree of uncertainty regarding these sweeping value judgements levied against people you disagree with is not very striking.
True skepticism is directed first and foremost at one’s own beliefs, and next at the thing one wants to believe. Being skeptical of ideas and people you dislike is not any notable accomplishment.
Why don’t you set an example? What is your level of uncertainty regarding the varies “skeptic” tropes you repeat as fact above: “pal review,” for example.
1. What is the chance you are wrong about the peer review system?
2. If you were wrong, how would you know?
3. What do you think is the strongest argument against your belief?
I am an admirer, a participant, and critic of peer-review as I have observed in my own field many of the pluses and minuses that have been evident in climate science. When the field is new and the pool of reviewers seems small, ie, reviewing one anothers manuscripts , venturing outside of the field for reviewers has proven “golden” as insights have been novel and informative. Reworking manuscripts again and again, even journeying back to the original occasionally has been informative to me. I have been able to enlist people outside of my field who comment on portions of the science I have prepared. This way of using non-field experts, yet scientists in their own right although of different disciplines, seems to be what the blogosphere provides and I am very comfortable with those exchanges. Arguments against my belief? Consensus.
Robert said: “True skepticism is directed first and foremost at one’s own beliefs, and next at the thing one wants to believe.”
And here is the difference between science and non-science – beliefs aren’t a part of science.
The beliefs are very much a part of science. Scientific knowledge is always a set of beliefs and data that provides more or less support for the beliefs. (Classifying something as data is by itself a expression of belief.)
Absolute beliefs are not a part of science but beliefs that can be disputed are. Every scientists has her set of beliefs and the scientific knowledge is just some kind of weighted combination of these individual beliefs.
How is it that a journalist uses extreme expressions like “The future of human life depends on how we respond to the risks of climate change” as if she is certain our future is doomed in an article about the uncertainty of climate change?
How is it that a journalist who is certain we can stop climate change, knows the eventual intolerable/unacceptable outcome but has no idea what the timeline of when it will happen?
How is it that a Professor from Penn State is so ethically confused about what climate uncertainty means but is certain “that increased damage from other kinds of storms is virtually certain as the planet warms” and “that tornadoes will appear in places that they would not likely occur in the absence of global warming”?
How is it that any of them are to be taken seriously?
Because in the age of AGW bs, bs on the weather is what sells.
Historians are really, really really going to enjoy reading Mann, Romm, Schmidt, Jones, watching Gore’s movie, greenpeace garbage, etc. etc. etc. and analyzing how crap science and transparent huckstering fed a global social mania.
Who was that idiot in the late 1980’s who said we were at the end of history because the cold war wound down?
“Historians are really, really really going to enjoy . . .”
You want to be realllly careful with that “history will vindicate me” line. It’s a favorite of tyrants, scadel-ridden politicians, and crackpots everywhere.
Robert,
It is also a line used by those who happen to be correct, but ahead of the curve.
Crackpots, as well as Einstein, also said, ‘please pass the sugar’.
But you do get an ‘a’ for obfuscation.
And since the AGW movement, like eugenics movement, is falling apart in most venues well short of imposing the ridiculous wasteful policies its promoters so vociferously demand, I think you are much closer to crackpotdom than you care to admit.
Why do you expect a journalist not to reflect the science as understood by the vast majority of climate scientists, dozens of national academies of science, the US military and the CIA?
It’s silly to expect a journalist to share your fringe beliefs, and disregard them if they fail to. That rapidly becomes a device to shield yourself from the evidence that you are wrong: the only people who you feel show your doctrine proper respect are the people who already believe in it.
I’m not saying you have to change your mind; but the chip on your shoulder is neither rationally justified nor helpful to your cause as a non-scientist attacking a well-established scientific theory. Be positive, not negative. Jehovah’s Witnesses’ don’t get outraged that the vast majority of people find many of their beliefs absurd; they are out there with smiles on their faces handing out “Watchtower.” That works better than abusing people for accepting blood transfusions.
Be positive, not negative.
I found the juxtaposition of their certainty with their themes of uncertainty mildly amusing… nothing more than that Robert.
OK, point taken.
Lubos Motl’s rather colorful take on Donald Brown’s piece:
http://motls.blogspot.com/2011/06/does-ethics-require-us-to-believe-in.html
Especially Motl’s point;
I’ve only gotten to the end of Chris Mooney’s statement – and I’ll have to take this one piece at a time.
Of Michael Lind’s statement (or rather partial quote) he says –
In one sense, this is obviously true. In another sense, it’s completely off base.
Is it true – or not? He doesn’t explain, but uses Kerry’s quote to claim Lind wrong.
In soliciting advice, we should be highly skeptical of any expert who claims to be certain of the outcome.
Unfortunately, he seems to miss the point that Lind speaks of low end probability, not “certainty? And the Mooney goes here –
We don’t know the timeline, but if we don’t stop it, we know the eventual outcome–and it is intolerable and unacceptable on any timeline. And that’s why any attempt to minimize worry about global warming by citing “uncertainty” about the projections just doesn’t make sense.
where he assumes we know the outcome. But he doesn’t – unless he has a time machine and has been to the future. IOW, he violates both the letter and spirit of the Kerry quote that he just used to attack Lind by expressing certainty about something that he cannot possibly know. .
And then, while he’s making predictions, he tries to minimize how obviously inane he’s being by calling those predictions “projections”. Does he know the difference? Does he care? Or does he not even realize how ridiculously inconsistent he’s being?
Sorry, but what’s there is confusing, inconsistent – and not conducive to belief in his competency as either a scientist or an author.
More later – but without certainty. :-)
Mooney should stick to cool-ifying scientists. Clearly, more hair gel is needed for most of you uncool scientists out there.
Jim,
I was also struck by Mooney’s comments following the Emmanuel quote. I mean, I guess we can’t consider Mooney an expert, so maybe the applicability of that quote to Mooney’s fundamental point is not valid. But if he’s not an expert, why are we paying attention to his opinion in the first place then?
You probably don’t want to see me harping on about what Judith Curry used to say and what she says now, but she used to argue the case so well I feel I can hardly improve on it :-)
“Think of risk as the product of consequences and likelihood: what can happen and the odds of it happening. A 10-degree rise in global temperatures by 2100 is not likely; the panel gives it a 3 percent probability. Such low-probability, high-impact risks are routinely factored into any analysis and management strategy, whether on Wall Street or at the Pentagon.”
Its all common sense really. I suspect none of us would rate the chances of our houses being burned down in the foreseeable future even as high as one percent. So does that mean we don’t have house insurance? I don’t know about you guys but I certainly do! If I thought the risk was as high as a few percent I certain would spend a few percent of my income to cover myself.
Its all about the product of “consequences and likelihood ” as I’m sure we all understand, even Judith Curry (the 2011 version)
I think only fantasist’s would suggest a 10C rise is 3% likely after the last 30 years of evidence. The IPCC track record on predictions is appalling bad.
Dr Curry thinks its 5%. At least she did a few months ago!
“The 2007 IPCC report predicts temperature rises of 1.1 – 6.4 °C (2 – 11.5 °F) by 2100. This is a wider range than the 1.4 – 5.8 °C increase given in the 2001 report. However, the 2007 report goes on to say that their best estimate for temperature rise is 1.8 – 4 °C (3.2 – 7.1 °F).”
Who predicts 10C?
“The 2007 report predicts that sea level rise by 2100 will be .6 – 1.9 feet (18 – 58 cm)”
And that isa goofy prediction because the current sea level rise has occurred at a mean rate of 1.8 mm per year for the past century.
So in effect the IPCC are predicting no change in sea level rise … and it looks like they are right. No change.
Therefore I would concluded even the lowest temperature rise predicted is not likely.
I entirely endorse your first clause.
‘You probably don’t want to see me harping on about what Judith Curry used to say and what she says now’
Just replace the word ‘probably’ with ‘definitely.
It may not be obvious to you, but your continuous tedious harping on the entirely unremarkable point that JC has altered her views in light of new information has already destroyed any credibility you may have had as a commentator.
Views change, ideas change. At least among those with enquiring minds. Perhaps yours don’t. Get over it.
I think it would be interesting for Dr. Curry to clearly express what her views used to be (before they were “altered”) and what they are now and see if there are any substantial differences. I’m guessing they are prolly more “lip service” type differences.
Andrew
@Bad Andrew
Well yes it would! And even more interesting if she explained exactly why she’d changed her mind. I know it’s supposed to be a female prerogative to be able to do that, but as a trained scientist she should know that changes of mind need to be backed up with scientific explanations not logical fallacies regarding leaked emails.
Or maybe she noticed that the catastrophes haven’t happen and don’t appear to be happening anytime soon.
Most of the global scare campaign took place during the warm phase of the PDO and during a very energetic solar cycle.
The cool phase of the PDO and the weak solar cycle seems to have resulted in a lot of cold weather and even dropping sea levels.
What Price Insurance?
What Coverages?
What Deductable(s)?
Sorry to say that all “things” change, as you’re well aware. It’s kind’a like “Global Climate Change”, y’know”? When things are good and the pay is good, you don’t normally spend a lot of time on the probabilities, you just buy the typical policies for whatever and pay the fees each month. When things aren’t so good and money is tight, you delete this and that and assume a greater risk on some things so you can pay for the essentials.
Things change! Today’s economy isn’t yesterday’s. Life is about taking risks and saving for rainy days whenever possible, sometimes the risks are higher because you can’t afford to by the insurance.
What’s the absolutely “essential” climate science “insurance” we need to keep paying on today (2011-2016)? Do we need to spend anything on it at all?
Politicians today are only interested in knowing what MUST be bought today with the few dollars we have in the kiddy. They are looking for ways to slash funding on everything and anything.
What Price Insurance?
What Coverages?
What Deductable(s)?
Indeed. The insurance analogy is far too simplistic. In addition to the factors you list above, there’s also that of compulsion – US mortgages typically require the maintenance of homeowners insurance, taking the decision out of the homeowners’ hands.
Hummmm… I vaguely recall there are a number of people, for want of income, defaulting and packing up and spray painting various explatives on the walls before leaving in the middle of the night and going to the nearest Salvation Army shelter over the last few years. (-;Ain’t life a pickle?;-)
Time tests all science.
Tonto52,
“Its all common sense really. I suspect none of us would rate the chances of our houses being burned down in the foreseeable future even as high as one percent. So does that mean we don’t have house insurance?”
I’ve seen this argument a number if times, or others very similar in meaning. The problem with it is that neither you or I would have that insurance if it cost each year as much or even a large fraction as replacing the house if it did burn down. Furthermore, I know I would not have it if I knew it would condemn billions of developing world people to generations of poverty and hunger.
Prove your solution is both cheaper and will feed hungry people. That is my response. Notice that the word is prove, not project.
Kerry Emmanuel: “In soliciting advice, we should be highly skeptical of any expert who claims to be certain of the outcome. I include especially those scientists who express great confidence that the outcome will be benign; the evidence before us simply does not warrant such confidence.”
Translation: Only listen to doom mongers.
My Prediction: The next ice is coming and will kill 90% of the people on this planet and we must do something about it now … preferably something that will cost trillions (I want my share) … and preferably something that will not actually solve the problem since predictions of doom are so much more lucrative.
Dr Curry
What would your level of certainty or uncertainty be as regards to this years tornado season being higher than normal due to AGW? You are obviously as qualified as any other climate scientist in the world to make such an assessment. Scientifically how likely is it that this years tornado season is abnormal due to increased atmospheric CO2?
If climate scientist are not willing to make such assessments because the science is not “robust” enough to quantify such narratives, then scientist have a moral obligation to condemn such speculative unscientific assertions.
In my opinion.
Jerry, Dr. Curry has a statement on this in the previous post:
http://judithcurry.com/2011/06/02/is-extreme-weather-linked-to-global-warming/
However, I think that all this talk of moral obligations and ethical requirements is wrong-headed, given that we are in the middle of a great public debate.
Thank you DW for responding for Dr Curry, I had not read that post and it does make her opinion clear. However being that we are in the midst of a “great public debate” makes it even more imperative that people of credibility make their views clear and denounce speculative narratives for what they are.
How can there be a debate if one side is allowed to present facts which are not in evidence while the other side is silenced or silent? This issue of AGW is far beyond a mere scientific dispute about some theory, it is having very real implications on people throughout the world. When fear mongering is used to promote something which is neither proven or verifiable in order to promote as fact a scientific conclusion which will then be used to promote policies which affect all mankind, then indeed those who hold different views have a “moral” obligation to refute them.
If truth is no longer a moral concept then I stand corrected.
Regardless I thank Dr Curry for stating her opinion which you have brought to my attention.
“..while the other side is silenced or silent?”
What is that silent side in this loud debate?
The silent side is the the side who is not given equal weight in the scientific, media, and political communities as to an opposing view. The silent side is the side which is mocked and ridiculed by their peers and in the “mainstream media”. The silenced side is not necessarily silent but rather silenced by institutional bias and if you can not see this in the “great public debate” on this issue then I suggest you should perhaps analyze your own prejudices.
…given that we are in the middle of a great public debate.
Are you sure this is true? Kyoto has been soundly rejected, and it looks like there is little more than vague hopes (on the part of chicken littles) that any sort of actual (enforceable/do-able) agreements can be attained internationally.
To me this is, as one semi-literate poster once (infamously) said elsewhere, the “death nail.” The good guys won. There ain’t as much debate as one would think.
In fact this business of Maggie somebody Baker and “prof” Brown and Trenberth lamenting the ignorance of the public, the notion of unhinged ethics, and idiotically trying to redefine the null hypothesis seems to underscore my point. It’s pure desperation. The chicken littles didn’t win, so the obvious response is to turn the screech dial to 11, vainly attempting to make it appear as if there is more to the chicken little argument than what reality says there is.
Thank you, thank you, Professor Curry, for continuing to expose the dogmatism that is used to hide uncertainty!
Dogmatic scientists and dogmatic religionists are identical twins hiding under different cloaks of respectability !
Climatologists are not alone in playing this game.
Astronomers, astrophysicists and cosmologists adopted the same technique as dogmatic creationists to hide uncertainty:
“In the beginning, God created . . .” versus
“In the beginning, the Big Bang . . .”
See comments on PhysOrg.com when astrophysicist Martin Rees won the 2011 Templeton Prize:
http://www.physorg.com/news/2011-04-uk-astrophysicist-million-religion-prize.html
Dr Curry –
I’m speechless, I don’t even know what to say regarding this one.
Some time ago I started saying NO when Penn State comes looking for contributions. And telling them “Why”. They’re not getting the message – yet.
“…We don’t know the timeline, but if we don’t stop it, we know the eventual outcome–and it is intolerable and unacceptable on any timeline. And that’s why any attempt to minimize worry about global warming by citing “uncertainty” about the projections just doesn’t make sense…”
With the amount of known “uncertainty” , they can predict the outcome?????
There is nothing wrong with saying “I don’t know”.
There is everything wrong with hiding your ignorance behind all this hocus-pocus about “Bayesian probability blah blah blah blah”.
And then this nonsense:
Where does she get this junk from?
Jack,
Sometimes there is something wrong with saying “I don’t know”. Just because we don’t know everything it doesn’t follow that we know nothing.
If you think climate science is strange, you should take a look at Quantum Mechanics. Cats can be simultaneously dead and alive in a superposition of quantum states!
Heisenberg was a principled in his advocacy of uncertainty! You’d think it was all hocus pocus and it does seem that way. The problem is – Quantum Mechanics works and there is no way that modern semiconductors, for example, would ever have been developed without it.
I strongly disagree. The most important right a scientist MUST have is the option to say ‘i don’t know’.
Without first admitting ignorance, you cannot move forward. Further, your analogy is flawed- the uncertainty principle is used as an example of the complexities of that particular branch of science. It is not the same as saying ‘i don’t know’.
@tonto52
‘Sometimes there is something wrong with saying “I don’t know”. Just because we don’t know everything it doesn’t follow that we know nothing.’
Under which circumstances of ignorance do you feel it is wrong to say ‘I don’t know’?
And no doubt your study of QM will have led you to the Uncertainty Principle which gives precise bounds on what can be know. And what even in principle can’t be known however clever you may be.
Please go and reread Feynman’s piece at the top of this article.
Better still, go and read all of Feynman. You will learn more about science, knowledge and uncertainty from him in an afternoon than you would in a million years of listening to climatologists – whose knowledge of scientific principles seems to be sketchy at best.
“The problem is – Quantum Mechanics works and there is no way that modern semiconductors, for example, would ever have been developed without it.”
Understanding quantum mechanics, and the Uncertainty Principle in particular, is neither necessary nor sufficient to the development of modern semiconductor technology. The first Schottky diode was in use long before QM was formulated, and mainstream IC technology is still largely driven by experimental work – the effects discovered are then explained using physical models.
The IPCC’s ‘handling of uncertainty’ was criticised by the IAC in its review of IPCC’s processes and procedures. ‘Poor handling of uncertainty’ and ‘vague statements not supported by evidence’ seems to be code for ‘exaggeration’.
Used car salesmen come to mind.
On behalf of the South London Guild of Purveyors of Previously Owned High Quality Conveyances to the Gentry, my fellow brethren have instructed me to protest to you in the strongest possible terms.
We have followed the shocking and distasteful history of the IPCC and all its ramifications and wish to express our collective shock and sadness that once respected scientists have fallen so low. And to dissociate the good name of car dealers worldwide from any such behaviour.
Please assure your esteemed readership of our finest attention at all times at Arthur’s Used Car Emporium. The finest wheels, the best deals. Strictly cash only. No paperwork is not a problem.
Arthur,
A snifter of Brandy does wonders to seeing IPCC as being correct.
Mind you, you do need many of them to see their point. :-)
Is it true that Pachauri is a graduate of the Arthur Daley College of Business Ethics? That would explain his repeated utterances about IPCC using “only peer-reviewed evidence”.
Nope. It is not true.
We strive to maintain the standards of behaviour for which car dealers are famed worldwide.
If Dr Pachauri were to apply to our college, he would need to sit the aptitude test like anyone else. Whether he could rise to meet our minimum ethical standards has not been determined.
Interesting.
Some of the pieces you link fall into the very trap they pertain to describe – that piece by Maggie being particularly ironic. She bemoans the lack of uncertainty-based science in teaching and then in the same breath asserts that cAGW is irrefutable and that we must all do something now or perish.
It seems the cherished art of hyperbole is not yet lost dear posters….
I’m finding myself having to change the way I look at uncertainty as I think I was too certain about the uncertainties- oh the irony. I’m certainly starting to doubt my position on a few issues.
I AM worried about the uncertainties and how they are being displayed and I’m SERIOUSLY worried about the level of expert judgement being employed (as it is not 100% clear when, how and by whom these judgements are made/used). However, due to the lack of clarity on these issues it can be very difficult to make any meaningful critiques on them.
This subject is very interesting and exceptionally important but I think that even when talking about uncertainty, people speak from, or at least appear to be speaking from positions of FAR too much certainty.
Uncertainty in ‘normal’ science I can deal with, I can tame it (at least in my work) and move forward. IN climate science I’m struggling. The lack of transparency and sheer complexity of the issue is giving me problems. Throw in policy, advocacy and the hard-liners and it gets even more complex.
I can’t help thinking that we desperately need to separate the policy from the science to get anywhere on this.
On a side note- i’d really love to see an ‘evidence’ tree approach in AR5- with highlighting of ‘good evidence’, ‘subjective evidence’, ‘slight evidence’ and ‘expert judgement’ being integral to the design. I think it’d GREATLY help the issue.
Heck, if i had more free time i’d try to do it myself- alas a 6month baby precludes such a possibility.
@Judith,
Are there any other branches of science with “nuances” ? Can you give us an example.
Dictionary definition of nuance:
No statement on the limits of possibility has much meaning without some explicit or implicit understanding on the minimum likelihood that qualifies as possible. Very many phenomena are formally possible, and perhaps even with a calculable probability, but not worth of being listed as possible in practice. As an example: All oxygen molecules in the room I am sitting now might go to that half, where I’m not, and stay there so long that I would die due to lack of oxygen. The probability of that can be calculated and is not zero. This example is of course extreme, but it illustrates that most statements on possibility are actually statements on probability or likelihood.
Based in part on the above observation my own view is that the only valid interpretation of probabilities and of possibilities is Bayesian in nature. All other interpretations are equivalent, invalid or cheating. Digging deeper in what people really think, the Bayesian approach is finally revealed, while it’s usually not explicit. Trying to make it explicit is very useful, although it may be extremely difficult to make quantitative. The attempt of making the Bayesian thinking explicit reveals, why it’s so difficult. It reveals, where the uncertainty is due to randomness and where to ignorance.
Using the Bayesian approach makes it also possible – and required – that the relative likelihoods of various alternatives are considered. Again this is often difficult, but again not considering the likelihoods is cheating. Giving equal weight to all alternatives passing the criterion of possibility is seldom justified. I used the word cheating, because the difficulty of making judgments is all too often used as an excuse for not reacting to the existing knowledge. The case of climate change is an obvious example. Having a wide range of uncertainty is not a valid reason for not acting, better arguments are needed to support that conclusion.
While I state above that the Bayesian approach is the only valid one, I’m certainly not saying that people referring to the Bayesian method would have everything right. The approach is so difficult to put in practice that it’s rather an ideal and goal than a ready-to-use methodology. I have been involved in several threads of this cite in discussions on the practical use of the Bayesian method. Reaching agreement on the practicalities has been difficult or impossible (and in one case I made serious explicit errors revealed after a couple of days).
My point is that giving up the Bayesian approach is not a solution, because all conclusions can be related to some version of Bayesian reasoning. When it’s not used explicitely, it’s still possible to invert the process at some level of accuracy and find out, what are the priod likelihoods that would lead to the conclusions. I.e., something is assumed implicitely even, when it’s not acknowledged, and often it’s impossible to justify those assumptions, when they have been revealed.
People have strong opinions on conclusions even, when these cannot be justified by logical reasoning, and even when the conclusions are in direct conflict with some other views expressed by the same people. The resolution is often that the conclusion is kept, and the other views considered less significant, but even in these cases the people should understand the correct nature of their views.
Pekka,
Ignorance is not random.
It is the lack of knowledge to make an informed decision.
Mind you, some people choose to be ignorant as not to be involved or protect their careers when new factors are put before them.
I come across a great deal of science and am amazed how NO mechanical component was looked at or incorporated into this. Just strictly baseless theories at the time sounded good but picked apart makes no sense.
Pekka i’d argue this point:
” Having a wide range of uncertainty is not a valid reason for not acting, better arguments are needed to support that conclusion.”
— as this is policy not science and therefore not relevant to this particular discussion.
I’d also suggest that although the bayesian method is quite useful, it does rely (disproportionatly so) on expert judgement. Which in my humble opinion, limitis it’s usefulness in this context.
In the first point I was not saying, how the decision should be reached, when one argument is excluded as insufficient. Neither do I imply that we could conclude from this observation that an action should be taken. The sentence should be interpreted narrowly without hidden implications.
I tried to make it clear that using the Bayesian approach is often very difficult, and that it’s often (or even mostly) done erroneously, when it’s used as justification for some proposed decisions. But my view is that the way forward is to learn to use it more openly and correctly, as the alternative is hiding the role of implied assumptions and prejudices. It’s better to make these openly visible than to hide them. Hiding isn’t limited to outsiders only, but the decision makers hide often the role their prejudices have even from themselves.
I can agree with that i reckon
Pekka, the problem with the Bayesian approach is that it doesn’t deal well with ignorance. Possibility theory has its limits regarding reasoning, I have been promoting an evidence theory approach instead of a Bayesian approach.
Judith,
Bayesian approach has difficulties with ignorance, but my view is that there is never full ignorance and that taking the limited knowledge into account is essential. Furthermore I think that limited knowledge is always influencing the conclusions, but this influence may have severe unidentified bias, when it’s hidden and not considered explicitly.
Your wide limits for the climate sensitivity can be used as an illustration. Taking at face value that the range from 1-10 C is possible, but nothing further is known, we are facing an extremely difficult problem of decision making. How much should our decisions be affected by the upper range? Should we consider as if we would have the likelihood of 11% for the interval 9-10 C? If our knowledge is really described by these limits, that would be a rational conclusion, and very many people would agree that we must then really react with extraordinary measures.
Not reacting to that possibility means that the decision maker doesn’t really take that range as one of a significant likelihood. She is not extending the ignorance genuinely to that range.
The difficulty of applying the Bayesian thinking can be illustrated also by keeping the same limits, but choosing whether we consider the climate sensitivity itself or the total feedback to be unknown in the sense that it has a flat PDF within the minimum and maximum values. The conclusion becomes totally different with the flat distribution for the feedback. That would make the values close to the maximal climate sensitivity very unlikely.
To conclude: Bayesian approach is problematic when ignorance is an essential part of the uncertainty, but it’s needed even then to make rational decisions.
One problem of Bayesian inference is that it may be used to overemphasize the value of specialist knowledge, but that must be counteracted by wider understanding of it’s basics.
Evidence theory and all other alternatives are in my view just more complex ways of hiding the prior distributions and of making them less understandable even for the person doing the analysis.
If the resulting lack of knowledge is used as an argument against acting, that result can be inverted to mean that the apparent lack of knowledge is used as a justification for the negative decision. As not acting is a decision as well, this is not logically sound.
Wide range of uncertainty leads to different optimal decisions than more accurate knowledge. More uncertainty favors robust choices, but it may also favor strongest known actions, if the uncertainty range includes genuinely catastrophic outcomes with a non-negligible weight.
Pekka,
What happens when mistakes are made?
Creating an enclosed like minded system totally ignoring any influence that may make a difference to the conclusion is what the “peer-review” system created.
You MUST follow the LAWS of science that was created even though they are full of uncertainties.
At least with mechanics, there are no uncertainties. Either it works or it is incorrect. But you must know every part and angle to understand the failures to achieve the success.
If your really intuitive, then you have to go back to find why mistakes were made in the past as the technology and social mindset was different.
Pekka, you keep falling back on the ‘If the resulting lack of knowledge is used as an argument against acting’ meme.
This is not what is actually being proposed- if a course of action is being proposed and the uncertainties lead to the merit of this action being uncertain, then not acting based off the uncertainties is NOT an argument for not acting, merely an argument for not taking the proposed action.
There is a subtle but important difference.
Not doing anything is one of alternatives. Choosing that is a decision even, if it’s done by avoiding all active decisions.
When there are many alternative actions deciding to do something is not yet a full decision, but requires further specification. Inability to choose any particular action is also a possible reason for not acting, and it may indeed be a valid reason, but that’s not always the case.
My own view is that we have now exactly such a situation, where knowledge on the potentially effective actions is not sufficient. Thus I’m not in favor of strong immediate policies, but would rather emphasize speeding up research on both relevant technologies and on understanding better, where policy alternatives would lead. While this is done lower cost robust choices should also be implemented. The robust choices might include a modest carbon tax, but not at a level that would lead to major misallocation of resources.
While this is my own judgment, I would not say that it’s a logical necessity, but rather a personal view on the balance of evidence.
“The robust choices might include a modest carbon tax, but not at a level that would lead to major misallocation of resources.”
What do you define as a misallocation of resources? A pigovian tax improves the allocation of resources by forcing producers to consider the negative externalities of their actions. Allowing a tragedy of the commons to unfold is the quintessential example of misallocation of resources.
Robert
What a carbon tax (in the USA as an example) would do is raise additional revenue for the government. That is undoubtly needed. What a carbon tax would not do is lower US CO2 emissions by an amount sufficient to be even measureable in impacting worldwide temperatures.
So are you say US emissions would not be significantly lower with a substantial carbon tax?
Or are you saying that the US, producing only 20% of the world’s emissions, cannot achieve the necessary reductions in CO2 emissions alone?
Robert
Essentially both. The abount of CO2 reduction that would result from the implementation of a carbon tax in the US would not lower US emissions by enough to be significant to the global CO2 level.
In order to get global CO2 to actually not rise would require a unified global response-and this has not and will not happen.
Given this post, it would seem to be the latter:
First, a factual point: the US emits about 20% of humanity’s greenhouse gas emissions. If we reduced them by a significant amount, say, half, worldwide emissions would be reduced by 10%. That’s significant. You are exaggerating, which undermines you credibility.
Second, I don’t think you can debate policy based on the assumption that current conditions are set in stone and political calculations never shift. We had Kyoto, which would have been far stronger if the US had participated and pressed for stronger targets. You pronounce that we are never going to have an international treaty to reduce CO2 again, but what is that based on besides your own wishful thinking? Is that conclusion characterized by ignorance, uncertainty, or doubt, or are you really certain?
Third, while we need international agreements, it’s important to get our own house in order as soon as possible. We should take a position of leadership and begin the transition to a low-carbon economy, and then encourage, cajole, and if necessary pressure the rest of the world to do the same.
The US and the EU still comprise some 40% of the world’s GDP. If they agreed on a carbon tax, and further agreed on sanctions against countries that did not implement a carbon tax, very few countries could resist such sanctions for very long. Japan and India are also democracies that are very vulnerable to the consequences of global warming. China might be a hard sell, but on the other hand it might be easier than we think, given that China’s leaders know global warming is real, know China is highly vulnerable to it, and are able to take decisive action when they want to. The US and the EU are also huge, indispensable markets for China; they could not tolerate sanctions.
Fourth and finally, while the politics of reducing greenhouse gas emissions seem difficult today, the world is continuing to warm and the consequences of that warming are continuing to unfold. The politics are going to get better as the damage gets worse.
Robert –
Thank you for you thoughtful response.
With all due respect, the topic or question related to a “carbon tax”. I have exaggerated absolutely nothing. There is NO POSSIBLE IMPLEMENTABLE PROPOSAL for a carbon tax that would result in a 50% reduction in US emissions. For you to suggest otherwise is rather silly.
Regarding global CO2 emissions, the burden must be on people like you to demonstrate that a global CO2 reduction plan is possible. The facts demonstrate that it has not been possible up to now. China, India, etc., etc. etc., have not committed to reductions from current levels, and never will imo; because it is not in the best interests of their populations. Virtually any currently less developed country WILL increase their CO2 emissions for the same reasons-they want electricity at the lowest reasonable cost, and people want transportation.
Your third point is based on the idea that the US (for example) should take expensive actions today with taxpayers nonexistent funds and HOPE that that the Chinese, Indians, Mexicans, Brazilians, etc. will do what you want in the future although they do not believe it is in their best interest. That would seem to make no sense.
You write a point that is a bit strange if you think about it more closely- Japan and India are very vulnerable to the consequences of global warming.
1. You reached a conclusion that Japan and India are especially vulnerable to global warming based upon what? Did you rely on the IPCC report that used a GCM that has been subsequently shown to be inaccurate? There is no reasonably accurate model available today to demonstrate the impact to individual countries.
2. Even if global warming was happening as you fear, and would impact Japan and India; their only course of action to prevent being harmed would be to construct proper infrastructure to prepare. The actions you suggest would do nothing to prevent the damage you fear for decades.
I appreciate your thoughts, but imo, what you have recommended does not make sense.
“I have exaggerated absolutely nothing.”
To say that reducing emissions in the country that produces >20% of the world’s greenhouse gases will have no effect on the global CO2 level is not true.
I agree with you that we cannot “bend the curve” all by ourselves, but as the second-largest producer of these gases, we could certainly have a measurable effect.
I was not saying that your assessment of the politics in the present day was an exaggeration, although I do think your confidence in predicting that this stalemate will inevitably continue is misplaced, for the reasons I outlined.
I have a question. When you say there is “NO POSSIBLE IMPLEMENTABLE PROPOSAL” are you referring to local politics, or technological limitations?
I don’t think technological limitations prevent this. And I don’t it’s helpful to use current politics when you are trying to agree on your goals. Once you agree on your goals, then it is time to argue about how and to what degree you can achieve what you want to achieve.
Here is a short list of policy changes in the US that appeared, at one time or another to have “NO POSSIBLE IMPLEMENTABLE PROPOSAL”:
*The emancipation of African slaves
*Women’s suffrage
*Prohibition
*Repealing prohibition
*The civil rights act
*Involvement in open-ended land war in Asia, with the public tolerating thousands of dead soldiers (note that this was considered impossible even BEFORE VIETNAM, and has been disproved many times since)
*Gay marriage (not all there yet, but clearly no longer unthinkable.)
*Electing a black president.
My point is this: committed people have often taken on hostile or indifferent majorities and ultimately carried their points (for better or worse.) So it is worthwhile to talk about what we should do, even if it doesn’t have a lot of popular support at that particular moment. Things change.
Rob, the site is eating my response. I’ll post it when I can, or if you’d like, I can email it to you.
Robert
You can e-mail me @ robert-starkey@att.net
I suggest that your base fear
“Allowing a tragedy of the commons to unfold”
is not currently justified, and if it was the only reasonable response is the construction of proper infrastructure to prepare for the forecasted environment. For a variety of reasons this is not done in most countries, but it is not the responsibility of US citizens to correct.
Robert,
Assuming for a moment that it’s possible to reduce US emissions by 50% by any means, let’s see what it would do:
The world’s emissions would reduce by 50% of 20%, ie 10%.
Half of that is absorbed by the oceans etc, so the net global emissions would reduce by 5%.
Now, as current emissions are adding ~1ppm per year (ballpark figure), the CO2 concentration in 100 years time will be 100ppm more, ie 490ppm. At 5% lower emissions, we’ll reach 490ppm after 105 years instead of 100.
That’s an awfully big ask to gain a measly 5 years in 100 years time, especially as that 5% reduction will be completely wiped out many times over by increases in emissions from China etc.
Secondly, taxes aren’t going to do it. In the UK they’ve escalated fuel duty to ridiculous levels over the last two decades – so much so that they can’t raise taxes any more without risking open revolt – and all it’s succeeded in doing is to push up prices and fuel wage demands. And emissions have not come down, just everyone’s poorer.
Robert
If you look back at my post I wrote a “what a carbon tax would not do is lower US CO2 emissions by an amount sufficient to be even measureable in impacting worldwide temperatures. “
I acknowledge that I was being somewhat dramatic.
It would be more appropriate to have written that a carbon tax would not lower the potential rise in future temperatures sufficiently to matter. I would guess (since I have no good data on the subject) that it would result in less than a .08C change in temperature. This is the high end temperature reduction that would result from ALL US coal fired power plants being shut down. Do you believe a carbon tax would reduce consumption more than that? What level of a tax would are you advocating? Do you believe that US voters would support such a tax?
The question on a carbon tax is what areas of the economy are elastic enough in their demand so that a rise in prices will greatly reduce consumption. Will we need or use less cement-not really. Would less be used by farmers?- probably not much. Would people use fewer utilities? Some, but certainly not 50% less.
How much do you believe that US gas prices would need to rise in order to lower consumption by over 50%? I am not sure it is even possible since people in the US need to drive. In my estimation it would require far more that a doubling of current gas prices.
Bottom line- a tax would have to be so high to reduce US CO2 emissions by 50% as to be a tax that would NEVER be accepted. The harm to the US taxpayer would far outweigh the potential benefit.
Trying again:
“I have exaggerated absolutely nothing.”
To say that reducing emissions in the country that produces >20% of the world’s greenhouse gases will have no effect on the global CO2 level is not true.
I agree with you that we cannot “bend the curve” all by ourselves, but as the second-largest producer of these gases, we could certainly have a measurable effect.
I was not saying that your assessment of the politics in the present day was an exaggeration, although I do think your confidence in predicting that this stalemate will inevitably continue is misplaced, for the reasons I outlined.
I have a question. When you say there is “NO POSSIBLE IMPLEMENTABLE PROPOSAL” are you referring to local politics, or technological limitations?
I don’t think technological limitations prevent this. And I don’t it’s helpful to use current politics when you are trying to agree on your goals. Once you agree on your goals, then it is time to argue about how and to what degree you can achieve what you want to achieve.
Here is a short list of policy changes in the US that appeared, at one time or another to have “NO POSSIBLE IMPLEMENTABLE PROPOSAL”:
The emancipation of African slaves
Women’s suffrage
Prohibition
Repealing prohibition
The civil rights act
Involvement in open-ended land war in Asia, with the public tolerating thousands of dead soldiers (note that this was considered impossible even BEFORE VIETNAM, and has been disproved many times since)
Gay marriage (not all there yet, but clearly no longer unthinkable.)
Electing a black president.
My point is this: committed people have often taken on hostile or indifferent majorities and ultimately carried their points (for better or worse.) So it is worthwhile to talk about what we should do, even if it doesn’t have a lot of popular support at that particular moment. Things change.
Robert and Rob Starkey
I have followed your exchange on a proposed carbon tax in the USA.
Rob Starkey has estimated that shutting down all coal-fired power plants in the USA would result in a theoretical reduction of global temperature by 2100 of 0.08C, and then adds the comment:
A carbon tax itself will not change our climate one iota, as I am sure you would both agree. No tax ever did.
But Rob’s temperature reduction estimate for year 2100 is correct for the Hansen et al. proposal to shut down all coal-fired power plants in the USA by 2030.
I have also calculated roughly what the investment costs would be to replace them with new nuclear power plants (the least expensive non-carbon based alternate). This figures out at $1.5 trillion.
A lot of “bucks” for not much “bang”, IOW a hare-brained scheme.
Global human CO2 emissions from all sources are around 34 GtCO2 per year, of which the USA generates around 6 Gt (17%). Other major emitters are:
China 20%
EU 13%
OPEC 7%
Russia, Asian “Tigers”, India and Brazil 5% each
Remaining nations 23%
See table:
http://farm6.static.flickr.com/5011/5500972088_54742f12be_b.jpg
Let’s say the USA not only shut down all coal-fired power plants, but also implemented other actionable proposals to reduce net emissions (conversion of most automobiles and trucks to hybrid or all-electric drives based on non-carbon based electrical power, major increase of domestic solar panels, concerted effort to improve energy efficieny both in industry as well as domestic use, etc.).
Let’s assume optimistically that the combined impact of these actions would be to cut CO2 emissions by 50% by year 2030.
What impact would this have on global warming?
Let’s take the “base case” (no CO2 cutback) to be the IPCC “scenario B1”, which assumes that CO2 concentrations will continue to increase at the same compounded annual growth rate (CAGR) as we have seen over the past 5 years (or the past 50 years) of 0.42% per year. This “scenario” forecasts a CO2 level by 2100 of 580 ppmv.
Cumulative CO2 reduction = 70 years * 3 GtCO2/yr = 210 GtCO2
Half of the human emission “stays” in atmosphere = 105 GtCO2
Mass of atmosphere = 5,140,000 Gt
105 * 1,000,000 / 5,140,000 = 20 ppm(mass)
20 * 29 / 44 = 13 ppmv = net reduction in atmospheric CO2 by 2100
Case 1 – No USA cutback = IPCC scenario B1
390 ppmv = C1 (CO2 concentration today)
580 ppmv = C2 (CO2 concentration projected by IPCC to year 2100)
C2/C1 = 1.487
ln(C2/C1) = 0.3969
ln2 = 0.6931
dT(2xCO2) = 3.2°C (per IPCC)
dT (2011-2100) = 3.2 * 0.3969 / 0.6931 = 1.83°C
Case 2 – 50% USA cutback in 2030
390 ppmv = C1 (CO2 concentration today)
580 – 13 = 567 ppmv = C2 (CO2 concentration projected by IPCC to year 2100 less cumulated reduction from 50% USA cutback)
C2/C1 = 1.453
ln(C2/C1) = 0.3734
ln2 = 0.6931
dT(2xCO2) = 3.2°C (per IPCC)
dT (2011-2100) = 3.2 * 0.3734 / 0.6931 = 1.72°C
Net reduction in temperature = 1.83 – 1.72 = 0.11°C
So Rob’s point is correct – shutting down a significant portion of the carbon-based economy in te USA will have no perceptible impact on our planet’s climate.
Max
Robert,
Pigovian tax on the level of the actual externality and linked specifically to the source of the externality results in the correct incentives, but who can tell the actual level of the externality and how often it’s possible to match precisely the actual source of the externality. In the case of carbon tax the second requirement is reasonable well satisfied, but estimating the right level is still very much open.
My view on what can be considered modest is higher than proposed by many others. It could be somewhere in the range that the emission rights have reached on the EU carbon market. A few dollars per ton of CO2 is too low to have any real effect. To give just some number $15-20 for t-CO2 is in the right ball park in my view.
Trying to force strong concrete measures, when they are not mature and when their indirect consequences are not known is something that I do not support. That has already lead to very questionable solutions for biofuels. The extensive investment in solar cells in Germany is another example of misallocation of resources as the generation of solar electricity has a value that is some 10 percent of the cost. (The proponents claim that there are large enough benefits from technology development to justify these investments, but I disagree strongly.)
I agree that the calculation of the precise negative externality is difficult. But I would place the minimum number much higher.
Take a look at this paper:
“Implications of incorporating air-quality co-benefits into climate change policymaking” (http://www.iop.org/EJ/article/1748-9326/5/1/014007/erl10_1_014007.pdf).
This suggests the average benefit of a carbon tax in improved air quality alone is on the order of $50/ton.
A carbon tax does not commit one to any given policy. The problems of biofuel and solar subsidies are precisely the problems it does not have, and exactly the reasons to support it in preference to programs targeting “winners.”
There have been many ups and downs in the prices for fossil fuel energy over the years. There are many taxes on specific activities or assets — property, payrolls, corporate taxes — without major problems.
On the other hand, we are rapidly entering a climate outside the relatively narrow temperature range we have enjoyed for the entirety of recorded history. That seems to me a much more important danger than any that might be anticipated from increasing the price of fossil fuel energy.
Robert,
In 1990s I was participating as the leader of the Finnish team in the international (EU and in the early part also US) collaborative research effort ExternE that tried to estimate external costs of energy production. Participating in the work and meeting other scientists, who studied various subtasks of the project and discussed the background and results of these estimates I saw, how uncertain and how dependent on difficult-to-determine coefficients the cost estimates of the environmental damages are.
The uncertainties are unfortunately not +50% or -30%, but rather factors of five or more. Making proper estimates is really difficult, and any of the estimates can be disputed by those with different points of view. Nobody participating in the activity was from the “anti-environment camp”, but the views were still so different.
The concept of co-benefits is also familiar as they have been an integral part of many models used in the research that I have been involved with since late 1980’s. The Table 1. of your link appears misleading in finding it only in two UK papers, but the weight the co-benefits get in the analysis has certainly varied also, when it’s an integral part of the approach.
All this experience is behind my view that determining the the level of externalities is very difficult and all estimates highly controversial. In absolute numbers it’s certainly possible to err more on the high side as the the error on that side may be more than 100%. The insentive is proportional to the absolute level of Pigovian tax. Thus it’s possible to err more on the high side also in fixing the level of the tax. The solution is not to set a level that is certainly high enough as that may lead further from the correct level than no tax at all.
As far as intolerable and definite outcomes of global warming if it happens — who sez? Current temps are nearly the lowest they’ve been in the last 30 million years, with a tiny uptick since the last Ice Age about one 3,000th of that time span ago. Geo-history doesn’t support either ‘definite’ or ‘intolerable’.
All of which begs the fundamental question of what causes warming. As a “driver”, CO2 reminds me of the kiddies in their carseats with a toy steering wheel attached. No matter how they twist and spin it, they’re really just along for the ride.
Judith,
Physics is a whole world of uncertainty.
Hidden behind the “Vail of Authority”.
This system generated a base theory and grew upon the theory which grew upon the theory over generations. Without a shred of mechanical backing.
Our basic understanding of planets comes from these theories which is from observed science off of one theory. The alternative is mechanical process that can be reproduced to show how what is observed is not necessarily correct only for the fact that technology was not advanced enough to go back and correct the error.
Judith, regarding uncertainty – you’ll have to forgive me as I’ve got a physics engineering and MBA degree + I’m doing part time archaeology. And each and every one of them treats uncertainty in a completely different way. So, I find it incredibly irritating when people try to use the methodology and therefore inherent “acceptable” level of uncertainty, from one discipline in another.
What I’m saying is the right way to treat “uncertainty” is very different depending on the problem you are trying to solve and so it varies greatly between disciplien. But, so long as people within one discipline always apply the same tests for “confidence” in their results, we all know where we stand and it works.
The big problem as I see it, is that climate “science” came almost out of thin air with no history or culture on which to draw to assess the “appropriate” way to treat uncertainty. Add to that the way the climate takes an awful long time to rebuke anyone who adopts an inappropriate view of certainty and … let’s just say, the treatment of uncertainty in climate “science” leaves an awful lot to be desired. The result is that a very unscientific treatment of uncertainty is being portrayed as “science”, when it clearly is not.
BUT. AND BIT BUT … that isn’t all the climate “scientists” fault. The NGOs and government bodies have been forcing this discipline to come up with answers “beyond the evidence”.
A public continually demanding answers, a lack of a deeply embedded culture which would have forced the highest standards when dealing with uncertainty and system that allows decades of speculation, decades of grant-grabbing by the most PR savy, decades of nothing to stop the charlatans embellishing the facts to suit their own politics … decades until reality rewards the few who have maintained their integrity and stuck to a proper conservative view of the uncertainties of their knowledge.
In some senses, it was almost inevitable that a new subject, left its own devices, attracting a particularly politically ardent group with such a long time frame between “prediction” and result would go off the rails.
In my view you are in such a mess that the only solution is for the whole subject has to be rearranged. First you’ve got to restore confidence in the basic data on which everyone depends. There is no reason why that can’t be done in an entirely neutral way by a group which has no axe to grind supporting one or other theory. But you can only restore public confidence if that group is totally independent from those who then interpret the data.
Next, there needs to be a much more level playing field for the subject with more equity for the various strands of research. From an outside perspective climate “science” has become far too introspective. The same people seem to be running everything seem to be involved in peer reviewing running the journals etc. etc. That may work in a subject where you can quickly cross-check another research group. But in a subject where a theory can be proposed as a Phd student, but never validated until after their retirement, people with (false) bees in their bonnet can dominate a subject and lead the whole thing up a blind alleyway — and the experimental evidence to prove they are talking BS just isn’t available until far far too late to stop them going up the blind alleyway. But by then, these people can run the whole subject causing it to adopt their ethics and treatment of uncertainty,
So, perversely, far from having the current “worst ethics in science”, climate science really needs to have the best possible ethics because it is just so damned difficult when the evidence takes so long to prove or disprove.
I can’t see anyway climate “science” can continue as a closed community setting its own standards. The standards of evidence in this subject has to match those of the rest of science. The standards of recruitment, journals, the ethics of public access, etc. etc. There has got to be oversight from outwith the area of climate.
And finally, somehow you’ve got to find a way to take the politics out of climate “science”. In some sense, you need a UK civil service code of “absolutely no involvement in politics – total impartiality – or you’re sacked”. Perhaps one way to do this is to create a new breed of “political scientist”, or “science advocates”: People with knowledge of the science, but who are able to express that knowledge without a rigorous requirement about how they treat uncertainty. More a “on the balance of probability” rather than “certain beyond reasonable doubt”. If you funded people whose jobs was to express the science in a political way, then that would remove any requirement for the scientists to engage in politics and it would enable you to enforce rules that they choose to be “scientists” sticking to the code, ethics and level of uncertainty for true of science, or they engage in politics where they can express their views in a less rigorous way – but not do so pretending they are real scientists.
Scottish Separatist (topical joke!)
A very interesting post, but I fear your proposed solutions, whilst highly desirable, are a bit idealistic and probably can’t be made to work in the real world. There will always be somebody with an agenda who will distort the science for their own purposes. Also, never underestimate the size of the scientific ego. Throughout history, scientists have defended their pet hypotheses to the grave and, indeed, it is often only when a new generation comes along that paradigms shift.
Scottish,
I do not wish to be little or attack your education or credentials.
But physics has missed a great deal by staying strictly to within it’s boarders of observed observation.
When it comes to gravity, the basis is on absolutely NO outside influences. Strictly the planet in inertia. This does not explain after 4.5 billion years why all the planets but 3 are in sequence to the suns rotation to within one day.
If the sun gives even the slightest tweak to the planet by magnetic field interaction, then all the physics behind gravity fails as now we are stuck to the planet by momentum. The sun uses reverse polarity to hold planets in place and rotational momentum of having the magnetic field slightly weaker at the back of the planet due to distance of the field traveling.
Great stuff Joe – for a first instalment!
Presumably the experimental proof of your assertions comes in Episode 2 and the maths behind it comes in Episode 3? Should I stay tuned?
For gravity, Newton wrote a big and famous book. Is your ‘debunking’ of him soon to come out too?
Because I know there are number of people with strong links to NASA posting here who have managed to do some pretty cool things by assuming that Newton was right. And they’ll take quite some persuading that he wasn’t………
Stirling,
The speed of rotation can be recreated to show how compression of mass and gases is a mechanical process in an enclosed environment. Centrifugal force is the tricky little bugger that always wants to exert outward.
Newton could never recreate centrifugal force as a coil spring was not invented yet to show how compression can be achieved in circular motion with weight and speed.
Please describe the experimental apparatus and means of measurement that show the phenomenon you describe. I would like to try to reproduce your results myself. Tx.
You do know there’s no such thing as centrifugal force, don’t you?
That’s a myth perpetuated by a poor understanding of physics. Centrifugal force does exist.
Joe Lalonde says enough ridiculous things on his own. Please don’t add more to it.
Brandon,
Describe all the forces acting on a point on the circumference of a rotating body, and in which direction they act.
There is no centrifugal force.
Alternatively, if you have a weight on the end of a piece of string revolving around you, and you let go of the string, which way does the weight fly? It flies off in a straight line at a tangent to the circle it was describing. In other words, it was attempting to move in a straight line all along, and it was only the centripetal force exerted by you holding the string which prevented it from doing so. As soon as the centripetal force disappears, it’s free to move in a straight line – which it now does.
There is no force acting outward from the center.
Peter317, I provided a link which gives an explanation as to why you’re wrong (and is funny). If you want to to understand the subject, I suggest you click on it. If you prefer not to, you could instead do a search for the Wikipedia article on centrifugal force. Either way, you’ll quickly see the only reason “centrifugal force doesn’t exist” is because people limit themselves to the inertial frame of reference. There is no reason for that limitation, so there is no reason to say centrifugal force doesn’t exist.
In short, you’re wrong because you are applying inappropriate limitations. Your physics teachers may have taught you what you are saying, but that doesn’t mean it is true. Even the most basic knowledge of coordinate substitution makes centrifugal force’s existence obvious.
And that doesn’t even touch on the subject of reactive centrifugal forces which exist in any reference frame…
Brandon,
You believe what you like. I can’t change that.
Centrifugal force is an imaginary force which acts in direct opposition to centripetal force. Therefore, if it was real, you would expect an object under the influence of centripetal force to move in the exact opposite direction to that of the centripetal force as soon as the centripetal force ceased.
But it doesn’t. It continues to move in the linear direction it was moving in at the point of time that the centripetal force ended – ie at a tangent.
Peter317, to be clear, you have completely ignored everything I said, as well as the sources I pointed you to. I will continue to believe what I want to believe, and basically every physicist in the world will agree with me. You, on the other hand, will demonstrate a severe lack of knowledge, a refusal to listen to those who disagree with you and a lack of either ability or desire to learn.
And with no regard for anything either of us has said, people will use centrifugal force in equations to solve many problems. This is because coordinate substitution is extremely useful, and rotational reference frames are far simpler to use for many problems than inertial reference frames.
Your link may be mildly amusing, but it most certainly doesn’t give ‘an explanation’ for why Peter317 is wrong. It merely asserts that he is. Assertion is not demonstration.
So, I ask you (as the insightful Stirling English asked Lalonde earlier):
‘Please describe the experimental apparatus and means of measurement that show the phenomenon you describe. I would like to try to reproduce your results myself’
Latimer Alder, yes it does. If you map Newton’s law’s of motion in a rotating reference frame, centrifugal force is clearly present. It’s just simple equations. If someone has trouble coming up with those equations, I can post them, but they could get the same from a simple Google search. Besides, if anyone doubted my comments, they could check Wikipedia’s article on centrifugal force as I suggested.
Peter317 didn’t ask me to prove anything. He didn’t ask for an explanation of my points. He just ignored what I said, and asked me to do something irrelevant to my comments (as he was limiting his question to an inertial reference frame). In a similar vein, your question doesn’t make any sense. You’re asking me to prove a term exists in basic equations by providing you an experiment. That isn’t how things work.
Perhaps I can save some time for those who might have trouble finding information about centrifugal force, though I’m not sure why anyone would. Here is an example of a problem being solved using centrifugal force (it even references the same link I provided). Here is the same problem approached without using centrifugal force. Finally, here is an brief answer on why centrifugal force exists.
Of course, all any of this says or shows is if you use a rotating reference frame, centrifugal force exists. If you need an “explanation,” I suppose you could say centrifugal force is an inertial force which is found in accelerated reference frames. That’s a true statement, but I doubt it would make sense to anyone who didn’t know the answer already.
You are putting the cart before the horse.
You claim a particular force exists. OK – lets go an measure it. We can measure gravity, we can measure electric/magnetic forces, we can measure the forces within the nucleus of atoms.
How do you propose to measure centrifugal force? If you cannot do so, then all you have shown is some mathematics without any proof that such mathematics has any relationship to reality. There are probably an infite number of mathematics where such applies, but I am only interested in the one that actually pertains here.
If you can’t show it experimentally, your assertion fails. Period.
End.
No more.
That’s it.
We call it ‘science’. As so often, Feynman said it best:
“It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are. If it doesn’t agree with experiment, it’s wrong”
Your assertions are a classic case of being wrong.
Latimer Alder, I don’t think there is any point in continuing this given your attitude. You didn’t respond to any of the content I provided. If you weren’t convinced I was right, but accepted I had provided enough to warrant interest, you would have just said something like, “That’s interesting, but can you provide something tangible to look at?” Instead, you made a rude comment designed to ensure no meaningful discussion could take place. That’s enough to tell me to leave.
But here’s the tricky thing about all this. The mathematics I highlighted show how one gets a centrifugal force from normal situations. That means if you made a setup to examine the forces in those sort of situations, you would find a centrifugal force as long as you used the “right” reference frame. In other words, centrifugal force has already been proven by all the experiments done with rotational systems. All that’s needed to see it is the simple mathematics I provided, and you ignored.
OK Brandon. I will ask nicely:
What you linked to was interesting, but can you provide something tangible to look at? Like an experiment, not a clever mathematical construction.
I await your reply with great interest.
I would point to the fairground ride where you stand against the inside of a circular wall that rotates, pushing you against it, and then its axis tilts over and you are still stuck to it despite gravity. That push is the centrifugal force. There are many ways to demonstrate it with various fairground rides. The Coriolis force also follows from the same equations that originated with Newton’s laws. Brandon has been saying things that are in basic university physics, if not high school.
I remember being advised against using the “centrifugal force” in my undergrad days but I must admit I always thought it was a handy concept.
I think Wikipedia sums up the present and historic thinking on the topic very well.
http://en.wikipedia.org/wiki/Centrifugal_force
In a rotating frame of reference it is just there, and its strength depends on the speed of rotation. Coriolis, its sister force, is obviously very important on the earth’s surface. It explains a lot of meteorology. If earth wasn’t rotating, it wouldn’t exist.
Y’all must really be bored to be wrangling over this. :-)
And I’m not about to wade through all of it. But I’ll say this much –
In an orthogonal system –
Centrifugal/centripetal force is not what keeps the Moon (or a spacecraft) in orbit. The Moon’s natural velocity vector is a straight line (as defined by Newton) modified by the mutual gravitational attraction between itself and the Earth. So it’s composite motion is (very) roughly circular with two component vectors (actually more, but let’s not complicate this).
One component is the straight line velocity vector and the other is the gravitational force vector (which is sometimes called centripetal force). Centrifugal force is the perceived (but not real) opposite vector (in both direction and amplitude) to the Earth/Moon gravitational force vector. Centrifugal/centripetal forces are not intrinsically “real” forces, but are named as such for convenience in many applicatons (rotating machinery design, for example). While the words are an artifact of older mathematical constructions that are still useful concepts in mechanical design applications, Vector analysis and orbital mechanics render them moot.
This can all be translated to circular coordinate systems. AND it can all be explained much differently in Relativistic terms. AND… but lets not go there.
I’m tired and haven’t said this all that well, but you’re both right. Get some sleep – which is what I’ll be doing. :-)
Jim D points to an obvious example. If one wanted, he or she could set up some sort of scale on the wall of the ride, and that would measure an actual value for the centrifugal force. Personally, I don’t see the value in such an experiment. It seems like asking someone to measure the normal force to prove it exists. It can be done, but what’s the point? You don’t need to directly measure it to calculate it’s value, much less to simply know it exists. Does anyone really think we need to directly measure a force to be able to accept it exists?
Besides, if a force depends on one’s frame of reference, a measurement is meaningless to the discussion. What that measurement is measuring will depend upon the frame of reference one chooses. That means the issue still comes down to mathematics.
And for what it’s worth Jim D, it is definitely university level. In high school physics, students are often told centrifugal force doesn’t exist, and most teachers probably couldn’t explain the nuances.
‘Does anyone really think we need to directly measure a force to be able to accept it exists?’
With the exception of the word ‘directly’ ..which cannot always be done (eg for very distant objects), I do.
I want you to show me that there is a particular force (centrifugal force) that is not one already known elsewehere. That it can be measured in a reproducible way and that those measurements can be used in calculations that make verifiable predictions about how future experiments will behave.
I can do that for gravity..I can do that for electr0-magnetism, I can do that with relativity.
Show me that you can do the same with ‘centrifugal force’.
I pointed out the example of the normal force for a reason. It was known to exist long before any sort of measurement of it could be made. Do you take issue with that?
Centrifugal force is in the class of inertial forces. If you are in a windowless elevator, and it accelerates up or down you feel a force in addition to gravity. If it was rotating on its axis, you would only know it by an outward push, and that is the centrifugal force. Any acceleration puts you in a non-inertial frame of reference, of which rotation is an example. Agreed, Brandon, these equations were in second year physics for me. I can’t remember what I knew in high school, but certainly not the derivation.
Folks
You are all confusing finding easy ways to solve mathematical problems by changing frames of reference with actual real forces.
Challenge:
You are armed with just Newton’s Laws of Motion. To make life easy, we’ll exclude quantum and relativity effects.
As you wander around the real world observing what happens like true scientists, which actual physical phenomena do you see that *require* there to be a centrifugal force.
Note: require. Not that postulating such a thing makes it a bit easier to do the sums using the 3 Laws. But are actual phenomena that *cannot* be described just by those Laws, but *must* also have a ‘centrifugal force’ to describe them.
I look forward to reading your replies.
The real world is rotating, but the centrifugal force is quite small. All you see is that it bulges at the equator due to it, but I am sure that won’t be proof for Latimer. I await his reply.
I’m well aware of all the arguments, and have been for a very long time. I agree that rotating frames of reference are useful, but centrifugal force only exists within such frames of reference, ie it’s not a ‘real’ force. Still, within a rotating FOR it ‘feels’ real, but, for most practical purposes, we do not live within a rotating frame of reference.
Like Jim D’s example of a ball being thrown within a rotating room. To an observer within the room the ball describes a curved path but, to an outside observer it doesn’t – it moves in a straight line (horizontally anyway)
There’s nothing which imparts any acceleration to the ball – it continues to move in a straight line. But, to an observer within the room, it moves in a curve, so the observer has to invoke an imaginary force in order to explain the ball’s motion.
@brandon
I can only conclude that you have a particularly odd sense of humour, since none of your supposed ‘funny’ remarks have been at all ticklifarious.
To sum up the ‘debate’ about ‘centrifugal force’.
a. You have proposed no experimental evidence that such a force exists. Any effects that you have described are perfectly natural consequences of Newton’s Laws and do not need an additional force to describe the phenomena.
b. Your lack of understanding of my desire to see some experiments..and you reliance on the contrary belief that ‘if its in the maths but not reality, reality must be wrong’ tells me that you are climatologists, not scientists.
Peter317, as I have explained, we live in a rotating frame of reference. These forces, though often referred to as “fictitious”, are useful. The Coriolis force comes into this too. Nobody learns atmospheric dynamics without them as an integral part.
Jim D –
“Frame of reference” (coordinate system) doesn’t make any difference except for the conversion factors. Force is force and is just expressed slightly differently. IOW – it still produces the same effect regardless of which coordinate system you use.
I used the Earth/Moon system as an example last night – you can just as well use your fairground ride, or a centrifuge or a high speed traverse of a sharp turn in the road. It still comes down to initial body vector and the application of one or more secondary force vectors. The reason “centrifugal” is confusing is that the secondary vectors can be generated by diffrent mechanisms.
Also, by the same coordinate substitution, the speed of light limit of the velocity of an object also dissapears.
If centrifugal force exists then there is no limit to an objects velocity.
Re Fairground ride:
Surely that only works because the wall of the ride is pulling you down faster than gravity would? No centrifugal force needed.
Put it this way. The outward push when you are rotating is the centrifugal force. You can’t deny that there is a force/push. What would you name it?
Inertia. A body carries on in a straight line unless something tries to disturb that motion. It is not ‘you’ exerting an outward push on the ride..it is the ride pushing you away from straight line movement. simple experiment. Suddenly take away the ride and bodies fly everywhere. Their tendency to stay in straight line motion reasserts itself.
Or a catapault (sling shot) shows exactly the same behaviour. There is no need to invent ‘centrifugal force’ to explain these things.
It may be an easier way to solve some equations to pretend such a thing exists, but that is just a mathematical ‘trick’, not an observation about the real world.
I think you are having trouble with the rotating frame of reference concept. Things don’t go in straight lines when you and your measuring system are rotating. Try tossing a ball to someone else on a roundabout. Seen from outside it goes straight, but seen from the roundabout it curves because your measuring stick is rotating.
The frame of reference is how you solve the equations.
I actually want to see some demonstrable real world proof of the existence of ‘centrifugal force’.
With like y’know, an experiment thingie. Like grandad used to do way back when. Maybe I’m old fashioned, but I kinda like to see the f…g experiment, not just the theory.
Jim D, he seems to be trying to differentiate between “real forces” and “fictitious forces.” Only, he is doing so without making any effort to learn about the topics. The Wikipedia article on centrifugal force gives enough information for him to sort out his confusion, but he doesn’t seem to have read it. I have no problem with the distinction he seems to be trying to make, but because he doesn’t understand it himself, he’s making nonsensical remarks.
On a humorous note, he says we can measure gravity, but gravity isn’t a real force! This indicates his standards are entirely based upon intuition rather than an understanding of the physics involved. There’s also a humorous note on him saying your example isn’t centrifugal force, it’s inertia. Newton defined inertia as:
The vis insita, or innate force of matter, is a power of resisting by which every body, as much as in it lies, endeavours to preserve its present state, whether it be of rest or of moving uniformly forward in a straight line.
Experiment. Take a windowless rotating room. Toss a ball to someone else and it goes in a nice vertical arc. Now rotate that room steadily. The ball will curve sideways too. The mathematics that explains that acceleration includes a centrifugal and coriolis force. If you stand outside the room, you don’t need those forces to explain what you see.
Please point me to the writing where I stated that gravity is not a real force.
Also please explain you remark:
‘There’s also a humorous note on him saying your example isn’t centrifugal force, it’s inertia. Newton defined inertia as:
The vis insita, or innate force of matter, is a power of resisting by which every body, as much as in it lies, endeavours to preserve its present state, whether it be of rest or of moving uniformly forward in a straight line’
Newton’s quote exactly illustrates my point. The body wishes to move uniformly in a straight line. The wall of the ride is stopping it from doing so. The ride is pulling the motion away from straight line by exerting a force.
Please point me to the writing where I stated that gravity is not a real force.
You didn’t. I did. I find it funny you cited our ability to measure gravity as an example because gravity isn’t a real force. That means you tried to say centrifugal force isn’t a real force by contrasting it to something that isn’t a real force…
Newton’s quote exactly illustrates my point.
If you read my comment, you’ll notice I made one word of his bold. That word was force. I thought it was humorous since you said it was inertia, not a real force, at play. Newton defined inertia as a force, so it sounds funny.
> The outward push when you are rotating is the centrifugal force. You can’t deny that there is a force/push. What would you name it?
If this force can be thought to be made of some pushes made on a blog thread, I’d name it the Latimer Effect.
When it’s a very strong push, we could name it the Sixpack Effect.
When it’s a graceful push, we could name it the Stirling Effect
:-)
“The NGOs and government bodies have been forcing this discipline to come up with answers “beyond the evidence”.”
As I recall, they weren’t asking for “answers” at all until the scientists convinced them there was a “question”. What I suspect then happened was that the scientists, at first gratified by their success, quickly found they ran out of proper science to regale the “NGOs and government bodies” with, and had to start making it up as they went along, as they have been doing for some time now. Perhaps they were naive, but I don’t think you can exonerate them and blame it all on the pollies.
The lead-in quote by Richard Feynman is an excellent read for clearing the mind from all the clutter that has been floating around out there on the human-caused global warming issue (now re-branded into the more generic and all-encompassing “climate change”).
The cited op-eds are something else, though.
After reading them all, I see that they have one basic theme, and it is NOT “the science is settled”.
The fact that so many op-eds out there openly concede this fact is already a major breakthrough, which I could not have imagined just three years ago, as Nobel Peace Prizes and an Oscar were being handed out, the media were outdoing one another with increasingly catastrophic disaster stories, politicians were calling for immediate action to save the planet and the “mainstream scientists” were basking in glory. [Sic transit gloria.]
In fact, the theme now appears to be, “the science is NOT settled, so what should we DO?”
[My answer to that is simple: “settle the science first and then come back to ask what we should DO.”]
I do not know if Judith shares my view on this completely, although this seemed to be the gist of her testimony last fall before a committee of U.S. Congress on this question.
But none of the articles shared this rather straightforward viewpoint (had they done so, there would have been no need for an op-ed article, in the first place).
So let’s go through them with my reaction.
In a classical switch and bait approach, Maggie Korth-Baker, a freelance science journalist, tells us a) there is no scientific evidence that man-made global warming has anything to do with tornado intensity or frequency, b) that climate is such a complicated field that there is also no evidence that this is not the case, and (here’s the “switch”) c) the “Earth, as a whole, is warming as humans pump more and more greenhouse gases into the atmosphere” and “those rising global temperatures, and rising carbon dioxide concentrations, will affect our lives in a variety of strange, and often surprising, ways”..
So the “science is NOT settled” on the cause of tornadoes, but global greenhouse warming is happening, so what should we DO?
She acknowledges that there is currently indecision on this question and then suggests that the underlying problem behind this indecision is how science is taught in schools in the USA:
In this country, we teach kids that science is a collection of hard facts.
The rest is standard “post-normal science” and “precautionary principle” stuff, ending with an almost evangelical-sounding plea to the general public:
”Future of human life?”
“Real science?”
Sorry. NO SALE.
[At this point, I had to clear my mind. So I went back to the Feynman quote and read it twice, before moving on to the second op-ed by Chris Mooney.]
Mooney brings out the old saw that “uncertainty cuts both ways”, i.e. “exactly because we are so uncertain of the science, human-induced climate change (AGW) could be much worse than we anticipate”. This is a red herring (as any half-way informed reader can see).
Mooney closes with a dire warning regarding AGW:
”We know the eventual outcome?”</em
Hmmm… I thought the problem was that ”we do NOT know the eventual outcome”</em (i.e. the ”science is NOT settled”</em).
”and it is intolerable and unacceptable on any timeline?”
Sorry. NO SALE.
[Back to a double-read of the Feynman quote.]
The essay by Professor Donald Brown was entitled interestingly, “Why Ethics Requires Acknowledging Links Between Tornadoes and Climate Change Despite Scientific Uncertainty”
“Ethics?”
Brown starts off with the premise:
”scientifically uncontroversial”?
WHAT “climate change”?
This is a loaded statement intended to convey the message that AGW has been scientifically shown to be the cause of all these events, a message that is blatantly false and unsubstantiated.
Brown then starts extrapolating this with:
Wow! So the “science IS settled” (even if it isn’t).
Brown then runs us through the entire IPCC liturgy of impacts of GHGs on warming, consequences of warming on oceans, etc., impact of all this on extreme weather events, etc.
[By this time I was getting that déjà vu feeling as if I had just re-read the entire IPCC SPM report.]
Brown then concedes there is a likely connection between El Niño and La Niña and tornadoes, but (and here’s the clincher):
WHAT “evidence”?
WHAT “climate change”?
The message being conveyed here is that there is EVIDENCE that HUMAN climate change is causing changes in El Niño and La Niña events. This is an unsubstantiated claim.
Brown then does a switcheroo and adds some disclaimers regarding the length of data series available and the direct attribution of warming to increased tornadoes.
He then makes the curious remark that there is an
Adding:
Brown closes with a paragraph on ethics relating to discussing risks from human-induced climate change:
[By this time Brown has got me going around in ever-decreasing circles, so I go back to reading the Feynman quote to clear my head.]
Robert Smithson’s article on ”Communicating about Uncertainty in Climate Change” is mostly about exactly that: ”how to communicate” and (even more importantly, ”how NOT to communicate”
His article is interesting, in that he does not try to “make a sale” himself (like the other articles above).
He closes with an astute observation:
Indeed.
[But I went back to the Feynman lead-in one more time.]
Max
Max,
Currently, I believe climate change is the battle of the cold and warm air masses that are currently taking place that has generated a great deal disruptions to what was the normal pattern that were being observed for years by the change of the oceans currents. Keeping the equatorial region waters colder than normal and moving warmer waters to the Arctic regions.
This generated vast amounts of precipitation changes especially when the tilting planets brings on the winter season.
This is just my own observations.
Well said Max. When I skimmed through (I could not read it) what Judith produced my reaction was that, apart from Feynman, the whole effort was a pile of garbage, and no worthwhile responding to. I could not have bothered to put out the effort you have.
OK its the old “science is settled” debate? It is always, and will always, be possible to argue that the science is not yet settled. Science will never have been settled to the extent that all questions have been answered, and university science department have closed down having left Judith Curry and her worldwide colleagues wondering what to do next.
You seem to be happy to suggest nothing should ever be done on climate questions ever. Regardless of what the bulk of the evidence is. Regardless how much danger there might be. There will always be a reason found to wait and no nothing – well not just yet anyway.
What is it with you guys? How can you seriously think like that?
How about we are old enough and wise enough not to respond to every little weather perturbation as if the end of the world is just around the corner?
That we are cynical enough to observe that those with most to gain if such a crisis were to happen are those shouting loudest about it. And the worse they can portray it to be, the more they will gain.
And have noted that history is littered with doomageddon prophets, all of whom have been shown to be wrong (so far)
And finally that we take a very dim view of the documented professional and institutional behaviour of many of those at the centre of the climatology scares. Which makes us think that they are unlikely to be telling us the truth, the whole truth or anything approaching the truth.
That’s how I can seriously think like that.
tonto52
You state an opinion on what others think and then ask a question:
Let’s analyze this, in order to anwer your question.
“Nothing should be done ever”?
Not really, tonto. Any specific actionable proposal that can be shown to have a significant beneficial impact (on our climate, on real pollution of our environment, on our dependence on dwindling imported fossil fuels, etc.), should be subjected to a cost/benefit analysis, presented for decision to the one who will end up paying for its implementation (in democratic societies, this is the voting public) and considered for implementation if approved.
“Regardless what the bulk of the evidence is”?
Absolutely not. If there is empirical scientific evidence pointing to the need for a specific action, then it should be considered, by subjecting it to the above test. So far this is what is lacking here (check Feynman): empirical evidence, based on actual physical observations or reproducible experimentation, not simply model simulations based largely on theoretical deliberations.
“Regardless how much danger there might be”?
The concept of “danger that might be” is a rather non-scientific premise, based more on the emotion of personal fear (from reading too many IPCC reports, “tipping point” nonsense or media disaster predictions?) rather than anything else. It smacks of the old “uncertainty cuts two ways” saw: “we don’t really know how bad (or how insignificant) the computer-generated ‘problem’ might be, so we’d better act right now to stop it”. This is clearly an emotionally based “argument from ignorance”.
“Wait and do nothing”?
That is not what Judith, for example, is proposing. As I understand it, she is proposing instead to do something very specific: i.e. to get a better handle (i.e. less “uncertainty”) on the science supporting the premise that AGW represents a real potential threat, before jumping to implementing remedial actions to fight that threat.
There is a decision process here, which you (and the op-ed authors here) are trying to by-pass (I have not shown the final ratification step, where the voting public makes the yes/no decision, as described above).
http://farm6.static.flickr.com/5267/5695851735_713e9422ee_b.jpg
We have just completed step 1 (“is global warming real?”) and are trying to come to grips with step 2 (“is it primarily caused by humans or natural factors?”).
There are a lot of steps left before we come to implementation, tonto.
Like with any other action requiring large capital investment, the most critical phase is the scope definition step at the very beginning.
The cost of mistakes (or required changes in direction) goes up exponentially as we move down the process.
Let’s not by-pass the process, tonto.
Max
Recall the philosophers’ demands in the Hitchhikers Guide to the Galaxy viz. “We demand rigidly defined areas of doubt and uncertainty.” It seems that climate science has plenty of both.
It’s very necessary for scientists to have the freedom to say, “I just don’t know”.
Scientists may be unaware of the power they wield, simply by virtue of their title. When a scientist says something like, “It’s 50% certain that…”, lesser mortals and, more importantly, politicians and other policymakers, read that as, “Although we don’t yet have 100% proof, it’s an undisputable fact that…”, when a more correct translation might be, “There’s a 50% chance that I could be completely wrong about this”
Peter,
That will not happen.
We rely on them to educate us and our young(which influences their mindset).
Careers and reputation are created with some getting quite a hefty income from appointments or speaking engagements.
So, they will fight tooth and nail that they are the experts and are absolutely correct until physically proven otherwise.
Sad system really.
a scientist would never say something is 50% certain.
I know that, you know that, but Joe Public probably doesn’t
“Bad Things” is a meme of climate catastrophe, and is why people assert that certain bad things will happen that are not demonstrated in any way by science. For example, GCMs do NOT simulate tornados, because their resolution is too coarse. The historical trend for large tornados (mostly detectable with the same accuracy over time, vs small ones which are more detectable today that before): from NOAA National Climatic Data Center
http://lwf.ncdc.noaa.gov/img/climate/research/tornado/tornadotrend.jpg
shows a downward trend. The bulk of US tornados are more frequent during la nina. Similarly, hurricanes are not directly simulated by GCMs but require a bunch of subsequent analyses and the current consensus is NOT much of consensus about likely future trends. Again, the IPCC forecasts a modest sea level rise but advocates proclaim drowning. The disregard for the likelihood of the claimed bad things is stunning.
Every time you see such assertions, challenge them vigorously. Ask the hard questions. Probe the logic. Question them as if you were a thesis examiner with a grudge.
Do not accept all the BS about it all being laid out in a peer-reviewed paper behind a paywall somewhere. Get the proponent to lay out their argument in terms that all can understand (*). If they can’t do so, then they don;t understand it themselves.
Judith’s essay about her study of the IPCC shenanigans showed that many climatologists know quite a lot about a very narrow field, but feel able to pontificate by association about things they know nothing about and have studied even less. And it is these ‘useful idiots’ who sign up to the Consensus and other such anti-scientific nonsense.
As sceptics we have been guilty of being a wee bit frightened of challenging the alarmists on what we have perceived as their own turf. Many of us are at least as good scientists and engineers as the climatologists. And we have the advantage of knowing the ‘AGW’ literature and arguments far better than they do.
Get in their faces….don’t concede an inch (even by omission to challenge) and lets see how good all their alarmist nonsense really is.
*I have in mind getting answers at about the level expected in an A level physics or chemistry paper. For those unaware, A levels are the public examinations in UK taken at about age 17/18 and are prereqs for university entry. To gain three or four good grades in hard science A level (eg Maths, Physics, Chemistry) is a very sound foundation for a scientific career.
The problem with “environments” is that they tend to mix with other “environments”. Today, we find ourselves in a very different financial environment than we were in a few years ago. This is having a BIG impact on the way we all look at and feel about things in every other environment. In a way, its sort’a like being in Japan; a huge earthquake, followed by a tsunami, followed by reactor meltdowns, followed by radiation releases, followed by contamination, followed by….etc. It’s enough to take your mind off what to buy some college or universtiy for Christmas.
It seems to me that as actual temperature outcomes in this century continue to favor the low end of the the IPCC projections, global warming advocates will increasingly emphasize uncertainty to give credibility to their high end projections, for which drastic action is required. Reduction in uncertainty is not compatible with their objectives unless actualizations change.
The real world data on temperature change from 1850 (or 1750) to today shows an increase of 0.6 to 0.8 degrees; we can express the uncertainty by saying the increase is 0.7 +/- 0.1 degree. During that time, the CO2 level increased from 300 to 400 ppm (285 to 385 ppm, rounded up). This is one-third of the increase from 300 to 600 ppm, which the IPCC claims will result in an increase of 3 degrees (though they give a range of values, 3 degrees is considered the best single prediction). Assuming a linear relation between CO2 increase and climate change, then one-third of 3 = 1 degree climate change should already have occurred from 1850 to today. This is already too high, outside the error bars imposed by the historic record. But it gets worse: because of saturation effects, doubling CO2 from 300 to 600 ppm will not double the heat absorbed, but will result in only an increase of about 9% (instead of 100%). This means that an increase from 300 to 400 ppm will result in a more-than-linear 46%, instead of 33%, of the total for 300 to 600 ppm. Thus a climate change prediction of 3 degrees on doubling from 300 to 600 ppm would logically mean a 1.4 degree change for an increase from 300 to 400 ppm. This is WAY OUTSIDE, on the high side, the uncertainty in temperature change in the historic record. Therefore the IPCC prediction of 3 degrees is wrong, too high by a factor of 2 (a straightforward calculation shows that CO2 increases alone, without including feedback, are sufficient to explain the 0.7 degree climate change in the historic record). This means that the IPCC prediction for an increase from 400 to 600 ppm will be 3 – 0.7 = 2.3 degrees (on subtracting the actual increase for 300 to 400 ppm), whereas the CO2-alone calculation predicts 1.4 – 0.7 = 0.7 degrees, a factor of 3 lower. Thus the problem is now resolved: the historic temperature increase from 1850 to today can indeed be attributed to increasing CO2, but the IPCC predictions of future increases are a factor of 3 too high (because they incorporated guesstimates for positive feedback which turn out not to be needed, as CO2-alone can explain the historic temperature change).
“The historic temperature increase from 1850 to today can indeed be attributed to increasing CO2…”
Or recovery from the LIA.
And the reason I say that:
HADCET – 12 Warmest June/July/August
16.93 1975
16.97 1781
16.97 1911
17.00 1933
17.03 1947
17.07 1983
17.10 1846
17.23 2006
17.33 2003
17.37 1995
17.60 1826
17.77 1976
http://www.metoffice.gov.uk/hadobs/hadcet/ssn_HadCET_mean_sort.txt
“The real world data on temperature change from 1850 (or 1750) to today shows an increase of 0.6 to 0.8 degrees; we can express the uncertainty by saying the increase is 0.7 +/- 0.1 degree. During that time, the CO2 level increased from 300 to 400 ppm (285 to 385 ppm, rounded up). This is one-third of the increase from 300 to 600 ppm, which the IPCC claims will result in an increase of 3 degrees (though they give a range of values, 3 degrees is considered the best single prediction).”
This is a common misunderstanding of the ECR. The 3C sensitivity to doubling takes centuries. ECR = equilibrium climate Response. It means this. You apply a force. That force has a response that takes time.
Like so. Imagine you are piloting an oil tanker and apply the rudder. Does the ship turn on a dime? nope. How about a jetski? yup. Same with the earth. Over a hundred year period you are looking at the TCR. the transient climate response. Big difference.
“because of saturation effects, doubling CO2 from 300 to 600 ppm will not double the heat absorbed, but will result in only an increase of about 9% (instead of 100%).”
Roger, can you point to some published literature that supports this claim?
I’m not sure where this comes from, but no-one is saying that doubling Co2 content will double absorbed heat. They saying, however, that a doubling (indeed any increase) will warm the atmosphere.
The IPCC say it will be in the range of a 1.5 -4.5 deg C warming.
Others , like JC, would give it a would expand the range to 1-10degC at 90% confidence limits.
Actually I gave it 0-10 C at 90% confidence limits. This bounds the sensitivity only, says nothing about a distribution or what is going on outside those bounds. Note, the following paper on an expert elicitation of sensitivities from IPCC climate experts bounded the range at 1-8C (h/t Paul Baer)
http://www.pnas.org/content/107/28/12451.full
Kew Gardens is a venerable scientific institution. Among many informative boards I saw there today was one which said (approx) “Climate change will destroy our planet.” Of course, climate change has occurred throughout Earth’s existence, and I can not conceive of any such change which would destroy it. Yet boards throughout the Gardens reflected this absurd premise. Uncertainty? Sorry, we don’t do that at Kew.
Another interesting post, Judith. I’d be very interested in your comments on the following paragraph (emphasis mine):
Holy hubris, Batman! Probability is what we say it is.
Me, I have real problems with that point of view. It is the work of the person you describe (correctly) as the “uncertainty cop” of the IPCC, Stephen Schneider, and forms part of the advice given to the authors and lead authors of the TAR.
w.
Willis, I have been railing against this since 2003.
Thanks, Judith, I just wanted to make sure I understood your position before moving on to the newer ideas presented above.
Moving on to the ideas of Ms. Koerth-Baker, she says:
Once again a talking head has popped up to tell us that it is a communications problem. Are we seeing a pattern here?
This time the claimed problem is that AGW scientists haven’t been able to get across the message that science is uncertain and messy … imagine that. A group who steadfastly holds that a) we can tell the average temperature of the planet a thousand years ago to less than a degree, and b) we can predict the climate’s responses to forcings over century-long timespans and c) flat out tells us that the probability of an event is whatever their “experts” say it is … and despite all that brilliant scientific work, somehow they’re having trouble communicating the concept of uncertainty. Gosh, who would have predicted that?
Again, however, let me point out that this is not a communications problem. The problem is not that the mainstream AGW scientists are unable to communicate their basic position regarding uncertainty to the polloi.
The problem is that the mainstream AGW climate scientists have communicated their basic position regarding uncertainty altogether too well for their own good. Take a look at the certainty that Mann claimed for the Hockeystick as a earlier example, and the story hasn’t changed since then. Quite the opposite—at present, the AGW folks claim to be more certain about their results than they have ever been. Their basic position is “uncertainty is what we say it is, and we’re really certain about our results, so they’re not uncertain”.
And the public has gotten that message loud and clear. I’ve said this before, and I’ll repeat it.
There is no communication problem at all.
w.
Willis,
That someone who claims to be scientifically literate wrote that as a serious point and not as farce- and that it has not been widely repudiated by others- is a damning indictment of the state of AGW.
Pekka advocates for the Bayesian approach to address uncertainty and provide transparency for the roles of implied assumptions and prejudices. The risk of a Bayesian approach is that it provides a number with which all sorts of mischief arises when this number can be used to justify a behavior or position. After all, this number is but a reflection of likeminded experts’ transparent opinions.
My point is a bit more complex. I assert that no other approach is capable of getting rid of the problems visible in the Bayesian approach, they can only hide the problems and make believe that the problems do not exist.
It’s a fundamental truth that all our understanding and knowledge is formed as an combination of prior knowledge and recent additions to that. All our perceptions are subjective manifestations of the same: prior knowledge and prejudices lead to the present perceptions. There is no way to get over these facts.
The Bayesian approach admits this truth and tries to handle it openly and systematically. That task is huge, and most attempts are failures in one way or another. The above June 3, 7:57 pm comment of Willis Eschenbach contains a lengthy quote that tells, how the Bayesian approach is supposed to be used in IPCC assessment. I agree with Willis and Judith that the approach is very problematic. It’s particularly problematic for science as scientist should not be looking for agreement, but trying to justify their disagreements. When the goal is agreement, it may be that the strongest personalities win rather than the strongest arguments, and even the strongest arguments are often nonconclusive and may soon turn out to be wrong, when they are on an issue of present scientific interest.
The essay of Lord William Waldegrave in the post “When Scientists Advise Politicians” tells, how it’s important that the scientists do not try to appear as unanimous when presenting science to politicians, but rather admit the disagreements. That’s the only way of maintaining the status of science in the long run.
Coming back to why I emphasize the importance of Bayesian thinking. The reason is in the alternatives proposed. The literature is full of different approaches that are supposed to solve problems in handling uncertainty and ignorance. Every time I have spent effort to find out, what these approaches really offer, my conclusion has been that they involve a great risk of leading to erroneous conclusions. The approaches start commonly in a useful way by finding some structure in the problem. That’s fine and can indeed be a valuable step, but then they typically assume that the structure represents everything that can be taken into account (or something close to that observation). They effectively limit, what information can be used and they provide some new spurious information, when the structure is given too much weight in the subsequent analysis.
The Bayesian approach can, in principle, handle all aspects of the problem, but only in principle. Therefore I stated in one of my earlier messages that it’s an ideal or goal, not a practical ready-to-use methodology. It’s, however, possible to look at the alternative methods and see, how consistent they are with the Bayesian approach in assumed test cases. That reveals typically severe faults in the other methods or at least that reveals, how limited and dependent on some specific assumptions the applicability of those methods is.
I think Pekka is right that pretty much all (maybe all) formal schemes for quantifying uncertainty end up relying on the same “Bayesian” schema. This is not the same as the particular mathematical formalism that has come to be called “Bayesian” but it is for many reasons not as powerful as its advocates would wish, except in some fairly narrow circumstances.
The bigger problem is that there are no robust mechanisms for aggregating expert judgment. The Moss and Schneider guidance paper which was cited above actually gave extensive suggestions for how to generate a “traceable account” of the collective judgments made by the chapter author teams; unfortunately such accounts are much easier in theory than in practice. Also unfortunately, new techniques which might inform such record-keeping won’t be available for the direct use of AR5.
–Paul
There are the things we know. And the things we know we don’t know. And the things we don’t know we don’t know.
Of the three, the last is by far the largest. The set of things we don’t know that we don’t know is infinite. In contrast, what we know and what we know we don’t know are both finite. Thus, certainty about the future is finite/infinite. It is for all intents and purposes zero.
Yet, many people, scientists included assume that the set of things that we don’t know is both finite and rather small in comparison to what we do know. This least to a false conclusion that future events are much more certain than they are. The only certainties are death and taxes.
fred berple and Pekka Pirilä
To the (Rumsfeld) quote you cite and expand upon:
You may both have read Nassim Taleb’s brilliant The Black Swan, which Judith has cited on an earlier thread about uncertainty in climate science today.
While Taleb does not write specifically about climate science, his observations on predictions would apply.
He addresses this specific point (bold type by me):
The old saw is often used in supporting climate science “experts”: “would you go to a dentist or to a plumber to have your teenage child’s impacted wisdom tooth treated?”
Taleb differentiates between “experts who tend to be experts” and ”experts who tend to be…not experts”
Our planet’s climate is certainly NOT a ”situation where tunneling is safe, because Black Swans are not consequential”.
That is why the “experts” do not do well making predictions of future climate.
There is the argument often used by IPCC (AR4 WG1 Ch.9): ”our models can only explain the observed warming after 1970 if we include anthropogenic forcings”.
This is an “argument from ignorance”. It assumes that everything, which can change our climate, is known. IOW it ignores ”the things we don’t know we don’t know”, which as fred berple has stated, are by definition much larger than the things we do know.
Whether we express the problem in frequencies or probabilities, our overconfidence in being able to project the future is based on a basic lack of awareness of our ignorance.
Max
Max,
Wherever the limits of knowledge are, and how ever the experts err in making their judgments, the decision makers cannot avoid making decisions, if not to act then to not act.
My feeling is that you prefer using reason in decision making. Is there any other basis for using reason than to take advantage of best available knowledge in spite of it’s all limitations. That’s all that I have in mind, when I say that the Bayesian approach is the ideal against which simpler and more practical procedures should be judged.
Nassim Taleb is advocating the view that the frequency of extreme consequences is usually underestimated, that we should prepare better to their occurrence, but do it in such a way that is of value even, if we cannot foresee the precise form of the extreme outcome. His results support precautionary principle, but also robust approaches to apply the precautionary principle.
Anyway the overconfidence of those, who belittle the possibility of a catastrophic outcome is more in conflict with Nassim Taleb’s views, as I understand them, than the overconfidence of those, who put a high probability to the existence of some severe tipping point.
Pekka Pirilä
Agree with you that “decision makers” should “make decisions”.
As you stated it:
You then add:
I agree.
I do not believe, however, that “not to act” is a viable decision.
Instead it is “to act now in better defining the uncertainties, likelihood and potential magnitude of any possible risks and benefits that could come from human-induced climate change”.
Judith Curry has alluded to this in her testimony before US Congress:
Go back to the decision process diagram, Pekka.
http://farm6.static.flickr.com/5267/5695851735_713e9422ee_b.jpg
We have just completed step 1 (is global warming real?) and are still struggling with step 2 (is global warming caused principally by humans or by natural factors?).
Let’s not by-pass the rest of the process and rush to respond urgently with policies that may fail to address the problem and whose unintended consequences have not been adequately explored, as Judith advised the congressional committee.
Max
Max,
From the point of view of logic I strongly disagree on the automatic conclusion that the steps 1, 2, .. should follow the chronological order as you imply at the end of your message. There is absolutely nothing illogical in the strong versions of precautionary principle, but these observations tell only that logic doesn’t solve our problems.
I agree with you that a major emphasis should be given on improving the level of knowledge, and on this point I would emphasize improving the knowledge on potential solutions even more than improving the knowledge on climate, although this is also important. Even an unanimous agreement on a severely damaging climate change is of little help, it the means to combat it effectively are missing or do not result in their intended goals, or if they are soon observed to be so damaging for the human well-being or societal stability that they cannot be continued.
In my view the largest uncertainties are on this front. Improving our ability to act would help also in meeting the challenges from the limited availability of oil and later also of gas. Thus these solutions are needed even if the global warming turns out to be near the lower end of the plausible range.
Pekka Pirilä
We have a basic disagreement here.
I believe we need to define the problem (or lack of problem) before we begin evaluating and defining solutions to the problem (or lack of problem), and that this all comes long before we start implementing solutions to the problem (or lack of problem).
An example:
If we find, after reducing some of the uncertainty surrounding our present knowledge (or lack thereof), that human GHGs have only a very minor effect on climate changes, and that these changes are caused principally by natural factors, which we are unable to control, then any costly “mitigation” actions we have undertaken prior to clearing up this uncertainty would have been “wasted effort”, possibly even involving “unforeseen negative consequences”.
The “precautionary principle” is a logical misnomer.
Real “precaution” involves figuring out a) if there is a potential future problem, b) whether or not this potential future problem is significant, and c) whether or not there is anything actionable that we can do to solve this potential future problem, d) what this action will cost, what it will bring and who will pay for it and e) getting ratification of those who will pay for it after presenting them a cost/benefit analysis, before we charge off to f) implement the ratified actions to “mitigate” against this potential future problem.
Charging off to respond urgently with policies that may fail to address the problem and whose unintended consequences have not been adequately explored is actionism, and not <precaution at all.
But, as this appears to be a basic difference between your position and mine, I hardly believe we need to debate this issue any more and just leave it that “we agree to disagree”.
Max
Max,
If there is a strong proof that the climate change cannot be dangerous, then the issue is settled. No disagreement on that. On this point more or less everyone is likely to agree. But do you propose that such a proof exists?
Wrong Pekka, that is a Trenberth like null hypothesis reversal. Climate has always been changing. There has been no evidence that human induced CO2 has caused anything anomalous or dangerous to the earth’s temperatures, climate or weather or anything for that matter. So talking of precautionary principle and solutions to a non existent imaginary problem is pointless.
“There has been no evidence that human induced CO2 has caused anything anomalous or dangerous to the earth’s temperatures”
That is incorrect. Are you not aware of data, or do you discount it for some reason?
I have certainly seen nothing that suggests that any small temperature changes supposedly observed through the fog of the noisy general signal are ‘dangerous’.
And since I understand that the temperature changes reveal themselves primarily in slightly less cool nighttime temperatures, I am hard pressed to imagine how anybody else could call such things ‘dangerous’.
‘Oh look darling its going to be 285K not 284K tonight’
‘Should I panic now darling?’
‘Well a guy with a beard on the telly says that this shows the world will end next week’
‘I think we’ll just have a nice cup of Ovaltine and switch the Central Heating off tonight then. We can let the guy with the beard do the panicking for us. He looks like he’s very good at it and has had lots of practice!’
Please enlighten me about why the bearded wonder is right and me and my g/f are wrong.
Robert, if such strong evidence exists then why do you imagine Trenberth wants to see a reversal of the null hypothesis?
Pekka
1. I propose that strong evidence (not proof) exists that our climate will change in the future, as it always has in the past, and that this most recent evidence points to a cyclical pattern in climate change.
2. I propose that no strong proof exists either that a) there will be a significant detrimental climate change, b) that such a climate change will (or will not) be caused by humans, c) that there is anything we can really do about it.
3. I also propose that there is no strong proof that the climate change cannot be dangerous (as you ask).
4. I propose that we should, as a precaution, spend our efforts reducing the high level of uncertainty and looking for empirical evidence (not proof) to support either of these assumptions before we charge off trying to solve the hypothetical problems that case 2 might present.
Don’t you agree?
Max
Robert,
irt the evidence of dangerous changes in the climate,
I have reviewed the evidence, not discounted it, and conclude thta interpretations of the evidence that conclude dangerous changes are occuring are incorrect.
Why do you think the evidence shows there is dangerous change occuring?
Are you ignoring the evidence or embellishing it, possibly?
Max,
I agree that your view is logical, but it’s not the only logical view. Choosing among different logical views depends on the (semi)quantitative estimates for the most relevant uncertain parts of knowledge. I added “semi”, because the uncertainties are large and involve much ignorance rather than randomness with a known PDF.
It’s has become clear that my estimates are not equal to yours. I see more evidence for the risk (not certainty, but risk of a sufficient likelihood) of serious consequences from the climate change. Therefore I support also stronger immediate policy decisions. I would like to replace the present EU policies by a harmonized carbon tax and strong support for relevant research. And of course I would also expect that European countries are not the only actors, but would be joined by all others, although the way developing countries would join might vary significantly.
Robert
You opine
“Evidence” refers to <em"empirical data based on verifiable physical observations or reproducible experimentation" as required per the scientific method (see Feynman quote ).
That is what is missing here, Robert.
Max
Pekka Pirilä
Pekka, I think we have agreed that our philosophy on this is different.
You see “precaution” as a call for remedial action to a postulated future problem.
I see “precaution” as getting better data together on the many uncertainties involved in order to clarify whether or not there really is a potential future problem before implementing remedial actions.
I suggest (to which you may not agree) that my position is based on reason, while yours is based on the emotion of fear.
We can parse words until we are both blue in the face, but we will not resolve this basic disagreement.
So I suggest we shift our discussion to other topics.
OK?
Max
Max,
I see precaution to require in this case two things:
1) Improving future capabilities and knowledge. On this we seem to agree.
2) Making immediately choices that reduce risks without introducing too high costs or new risks comparable to those being reduced.
I have emphasized that doing anything at all requires exceeding some limit of likelihood for the risk. The required likelihood is the less, the more severe the potential outcome is. The required likelihood is also the larger, the larger the costs and the potential new risks are.
I think the main difference between our philosophies concerns the type and the extent of evidence we require to initiate actions. I give more weight to subjective expert judgment, when sufficient direct empirical evidence cannot be obtained with best effort and without excessive delay.
Basing decisions on subjective expert judgments requires great care. In the case of strong climate policies the issues (supposed to be) covered by all IPCC working groups must be included, and more. The area of WG1 is the easiest, and even that is not easy. In my judgment the knowledge covered by WG1 is a strong enough reason to proceed with the assessment and look at the areas of WG2 and WG3, but here we face obstacles.
Most importantly we know so little on the real influence of policy decisions that we must be careful not to cause more damage than positive results. All really effective policies are certain to change very significantly the whole international economic structure and also many aspects of everyday life. This is recognized by people promoting such actions as can be read from this report of German Advisory Council on Global Change. They appear to believe that they tell about a positive future, but I cannot agree.
I disagree, Max. When it comes to climate the things we don’t know are actually pretty well known. The problem is that these well known unknowns are being ignored in favor of the AGW paradigm. The list begins with the mechanisms behind the ice ages, both big and little. (Never forget that we still cannot explain the big ice ages.) Then there are abrupt changes, the sun-climate linkages (especially indirect solar forcing), ocean oscillations, non-linear feedbacks, etc. In short, natural climate change. This list is a decade old but it still gets no funding. AGW proponents control the money.
David Wojick
I believe we are discussing “semantics” here, David.
You are referring to events as well as a list of mechanisms, which are pretty well known.
I was referring to another list of mechanisms that are unknown.
You mention a list of natural climate change mechanisms, which we think we know, even though we still cannot explain the big Ice Ages. But there are also mechanisms, which we still do not know and do not even know that we do not know. How big is this list?
In a post above fred berple writes:
(If you don’t like “infinite”, I think you can substitute <em"open-ended".)
The IPCC example (AR4 WG1 Ch.9) is a good one:
– We do not for sure know how the known mechanisms, which we think we understand, have affected the late 20th century climate.
– We do not know how the unknown mechanisms, which (by definition) we do not even know, have affected the late 20th century climate.
– Yet we conclude that anthropogenic forcing must have played a role, because we cannot explain the warming in any other way.
Max
Max, I do not think there is a “semantic” issue here (whatever that means, since when you quote a word you are signalling a new meaning), nor even a semantic issue. The things that we do not know that we do not know are unknown, hence they are irrelevant to the debate. My point is that there are enough well known unknowns to support skepticism.
For example, while the ice ages are known to have occurred in recent times, we do not know how or why. They are thought to be set off by the Milankovitch cycles, but there is no known mechanism that translates these subtle changes into abrupt climate changes. Even worse there is no explanation as to why these M-cycles, which are as old as the earth, suddenly and recently started creating ice ages. It is a huge mystery that should be the focus of attention in climate change science, but we are fixated on AGW instead, for political reasons.
Ohmigod.. what a dilemma!
In preparing for my doom, I need to know whether to wear my thermal undies or my bathers.
Surely climatology can help?? It has such a fine track record….30 billion dollars (just in the US) and it can’t even explain the Ice Ages.
If there were a cycnic round, he might wonder why no bright ‘scientist’ hasn’t got a grant to discover why ha;f of the Northern hemisphere was encased in several miles of ice for hundreds of thousands of years. And not just once, but many times.
But no, it is deemed ‘better’ to spend th e30 billion big ones on models that don’t work and on sealevel rises of nearly a whole foot in nearly twenty-five years.
And the cynic might wonder if the political agenda had overhauled the purely scientific one about 22 years ago? Just about when the IPCC was formed……
And if the scientists think that sacrificing their intellectual integrity for filthy lucre and political influence has been the Faustian pact that it appears to be?
In similar vein I wonder if they view declaring war on sceptics to have been an overall positive strategic move for them? Or whether history will show that it was as dumb as Napoleon invading Russia in the autumn?
Latimer, you are correct, except for the integrity part. The USGCRP (global change research program) was set up in 1990 and it has focused on developing AGW ever since, to the tune of $30 billion or more. (I think the USGCRP budget is over $2 billion a year, but that may change soon.) Scientists, like all of us, have to go where the work is.
One would think that understanding the triggering mechanism of the ice ages would be a priority. Ice ages are long (100 ky) and interglacials are short (10-15 ky?) so the threat is obvious. One does not need a computer model to see the threat.
But this issue gets zero attention because the USGCRP is political science.
Here is a colossal irony. It is speculated that the ice ages began as a result of atmospheric CO2 depletion. If the recent CO2 increase can prevent the next ice age that would be a huge benefit, well worth sustaining. But we simply do not know, and are not trying to know.
Hi David
I don’t disagree, but you are being a bit disingenuous with your implication that the scientists are just like an old taxicab plying for hire, available to the first guy who comes along, no questions asked.
I;m sure that the leadership of the USGCRP is strongly influenced by the opinion of scientists as to what to study and pay for. And I don’t believe that for 20+ years a posse of guys in whitecoats have been picketing the office shouting
‘Study the Ice Age now!’
while massed bureaucrats manned the barricades with
‘Away ye scum! You’ll study what we tell you and nothing else you lily-livered lab rats. Anyone caught even mentioning the Interglacials will have their access to journals removed!’
It ain’t like that. Scientists (via their scientific institutions) are complicit each and every step along the way. If (like me) you think that the navigation is misguided, you need to look hard at your own colleagues and their actions.
Judith did just that, and was ‘disappointed’ in what she found.
Latimer, while I enjoy your colorful scenarios, they are not especially useful in discussion. It is hard enough to understand what people mean when they say it. But I take you to be saying what is certainly true, namely that the climate community rushed to do AGW research. Science is just as prone to fads as any other human endeavor. But this is not a lack of integrity, if anything it is the dreaded opposite, namely an excess of idealism.
By the way, the last I knew (and I left the field in 2004) the ice age mechanism was seriously studied by the Belgians and the French. I would like to see the US do something here.
Sorry that you don’t find the little illustrations helpful. But others do, so I guess I;ll carry on doing them.
My point was not only that the scientists rushed to do climate research. But that they also had a very strong influence on what research was done. You cannot absoleve yourselves from responsibility from not doing the Ice Age stuff just by saying ‘you went where the work was’. You guys helped to define the work areas to be examined.
As to an ‘excess of idealism’, forgive me if I put on my extra super cynical hat. Idealism is something I expect in political activists. Not in scientists supposedly wedded to the objective truth.
Sounds to me like far too many ‘scientists’ saw global warming as a political crusade and not as a research topic. In so doing, the end justified the means and they all got themselves into the moral mire some brave ones (like Judith) are trying to navigate their way out of.
David Wojick
I agree.
Max
Judith
In the lead-in here, you wrote:
This certainly helped, but there is an even older reason, taken from the Bible: the case of “doubting Thomas”:
As Wiki tells us:
In this account, Jesus reappears before his apostles and tells Thomas, “Because you have seen me, you have believed; blessed are those who have not seen and yet have believed”.
In religious dogma, a “doubting Thomas” is one who doubts the absolute truth of the “Holy Scripture”.
“Born again” Christians often tell of how they were “doubting Thomases” before they saw the light.
From the point of view of science, rather than religion, I think the paragraph you cite by Richard Feynman tells it all.
It also points out a key difference between “science” and “dogma”, which is easy to detect in the following op-ed articles.
Max
Max,
Genuine skepticsm is fine and it applies both ways too. Like when we hear CEI, and other so-called think tanks, assure us that it is quite safe for GHG levels to be increased indefinitely without fear of any consequence. That is as good a time as any to start wondering if we are being told the truth or if there are any ulterior motivations for wanting us to accept a particular line.
Fair point
tonto –
Like when we hear CEI, and other so-called think tanks, assure us that it is quite safe for GHG levels to be increased indefinitely without fear of any consequence.
I haven’t seen that claim in quite those words before. Not saying it’s not true, but do you have a reference?
That is as good a time as any to start wondering if we are being told the truth or if there are any ulterior motivations for wanting us to accept a particular line.
No – you should have been skeptical long ago – as opposed to being certain that your side was right and simply dismissing the opposition.
tonto52,
Are you certain you have links to the CEI saying?
If so, would you please be so kind as to share them?
Smithson’s discussion of what he calls “conflict aversion” is central to the present situation. For example, he says “There are understandable motives for concealing or disguising some kinds of uncertainty, especially those that could be used by opponents to bolster their own positions. Chief among these is uncertainty arising from conflict.” This describes the “science is settled” strategy very nicely, a concerted effort to conceal the debate.
The fact is that the scientific conflict was hidden for many years, all but ignored by the mainstream press, but now it is out in the open. And as Smithson suggests, when the experts disagree the public trusts no one, a rational response indeed.
But the reality is much more complex than that. The public is not abstaining, rather it is choosing who to believe on ideological grounds. The environmental movement pushed the science beyond what it could provide (as usual) but it got called on the move, because of the magnitude. The inevitable result is politicization, or more accurately ideologicalization.
It is clear over time that Mooney is not contributing to this discussion at all.
But he certainly knows how to sell books and get cool jobs selling his ideas.
Koerth-Baker is right about science education, but for the wrong reasons. K-12 SciEd is not about science the activity, it is about teaching how the world works, as best we know. K-12 SciEd is not about how science works, any more than K-12 history is about how historians work, it is about the history of the world. In general one only learns about the debates at the frontier in grad school.
Climate change is different because it is basically a public policy debate, not a scientific debate. Climate per se is a minor element in the high school science curriculum, but its political prominence means that every science teacher either avoids it or confronts the debate, because the parents know about it. Interestingly, the College Board recently came out with a proposed new national standard for SciEd that confronts climate change in middle school and in detail. I doubt that this will fly because teaching 9th graders that science does not know what it is talking ab0ut is too hard.
When faced with known unknowns, simultaneously exploring many different and non-parallel alternatives can prove useful and compelling. During World War 2, combatant navies sought one another by sending out “scout planes” in a semi compass array. The most likely position of the enemy armada was but one of many possible locations explored. Indeed, scout planes headed on compass courses away from the launching aircraft carriers. Various strategies were employed to maximize the scout plane not overlooking an enemy flotilla. The probability test assumed that the enemy flotilla was likely someplace within a striking radius. Launch and recovery, launch and recovery of scout planes until a positive report. Now let us fast forward to the second decade of the 21st century. We know that climate changes, we seek to delineate its boundaries and influences. As with the WW 2 scout planes, isn’t it more likely than not that pursuing multiple non-overlapping avenues of inquiry would be fruitful, giving an answer sooner than later? There are likely many “blind alleys” or fruitless tracts. A researcher would need to set out parameters of success and failure prior to starting; mindful and alert as there is such a thing as serendipity. The only “losers” would be those whose research was on the non-finding compass course and had to turn back as they were running out of fuel. Isn’t this at least one of the reasons why such a probability research trial has not been envisioned? There is a benefit and a pitfall in employing an array strategy. The benefit is finding more avenues to explore; the pitfall is that the researcher puts on blinders and their narrow focus no longer allows the researcher to see the forest for the trees. Guidance as to who is going to follow which compass course becomes the tricky part and the political part of the paradigm. As long as the array is broad enough, and there are parameters for success and failure, then the rate limiting step is on-board fuel capacity, which the politicians ultimately control, and, although their deliberations may be opaque, their decisions are at least are transparent.
A good analogy. But the present situation is that it is falsely believed that the enemy has been found so all the scouts are being focused on the same place, to gather details. AGW is government policy, and has been for 20 years, and this hasty decision dominates the funding of research.
RiH008
Agree with David Wojick that this is a good analogy.
It is clear that the US Navy would have lost the War in the Pacific to Japan had they (in searching for the enemy flotilla) clung to a fixed hypothesis rather than “pursuing multiple non-overlapping avenues of inquiry” .
Max
My father is a Stampede Monday Boy. He enlisted in the US Navy on the morning after Pearl Harbor, and was in San Diego by the end of that week to begin corpsman training. His first ride was on a cruiser. One night in 1942 he was in a task force that was sent out to find and destroy the Tokyo Express, which was attempting to resupply the enemy’s army on Guadalcanal. During daylight, they catapulted their scout planes to deploy and wait along nearby shorelines. At that time many Navy officers did not like to have scout planes on their ships when engaging the enemy. Unknown to the officers on the ships, the air was too calm for them to get back in the air. Using prop wash, they were able to get one aloft, but he arrived after the battle was over.
In the middle of the night they had blips on their radar. The eyeballs in the nests did not see a thing. They also had guns that were aimed by “computers”.
The younger officers on the destroyers had their firing solutions and asked for permission to drop fish. Incredibly, that request was denied. Perhaps somebody did not trust radar. They waited for several agonizing minutes. A vastly superior US Navy force was sailing straight into an inferior enemy force, which was completely unaware of the US presence. Finally, the order to fire was given. Our fish had no chance. Our big guns lit up the sky. All it accomplished was alerting the enemy we were there. The enemy destroyers dropped their fish and scattered to safety. One was sunk. Minutes later the US Navy suffered its 3rd worst defeat in WW2: one cruiser sank; three cruisers knock out of action for months.
Maggie has something backwards here: “If we want people to understand science, we can’t just give them facts to memorize. Scientific literacy isn’t about being able to win a game of quiz bowl. It’s about understanding how science works, and how science can be used to guide human decision-making.”
Science isn’t about guiding human decision making. Science (and other endeavors provide facts. It’s up to analysts to select and interpret facts to guide decision making. In spite of the overlap apparent in the climate arena (the IPCC scientists are attempting to be analysts), the skill sets of scientists and analysts are very different.
K-12 science is not about understanding how science works (which by the way we do not understand well enough to teach). Nor is it about memorizing facts. It is all about understanding how the natural world works. The popular reform idea that instead of teaching people how the world works we should teach them all to be little scientists is a mistake.
If I may put a finer point on this… we should also be teaching them how to find out for themselves how the world works. That way, they won’t be unnecessarily and erroneously holding on to popular beliefs. They can find out for themselves what is true and discard what is false using their own judgement.
Andrew
BA –
Are you trying to say we should teach them to THINK?
What kind of revolutionary are you? :-)
This is the latest fad, called inquiry instruction. While a useful exercise in small doses, it is no substitute for learning. We cannot expect children to rediscover what it took the world’s finest minds 400 years to discover.
Let me put it another way. Inquiry methods take two or three times longer to teach the same content as simply explaining stuff. If universally used a 12th grader would only know what today’s 6 grader knows, but they would have figured it out themselves. This is the inquiry versus literacy traveled.
However, conventional teaching does teach thinking. That it does not is a myth. One person explaining something to another involves active thought by both parties. Moreover, we teach a great deal, roughly one basic concept every half hour. That we do not is another popular myth.
Sorry, it is trade off, not traveled. IPad speller overruled me. The point is that science education is a marathon of learning. I have been studying this for four years. See http://www.stemmed.info
David, I’m a bit puzzled by this.
You seem to be saying that high school science teaching does not have the time to teach the scientific method, and has to settle for learning “how the world works”. You also seem to be saying that the only alternative would be “inquiry learning” – which I would agree would take too long for a useful body of learning to be imparted.
But when I was taught science between the ages of 14 and 18, in the 1960s, in England (to “A” level), we were not only taught “how the natural world works”, but also the essentials of scientific method, or “how science works”. In fact as far as I can recall, the syllabus STARTED with a brief synopsis of the SM. In other words, in learning “how the world works” we also learned how it had been discovered. Furthermore, important aspects of “how the natural world works” were usually introduced by a description of the (repeatable) experiment/s that revealed it, thus reinforcing the priority of observation over theory.
Since I started taking an interest in climate catastrophism, it has become sadly clear to me that succeeding generations have indeed been taught in the way you describe, with the results we are all familiar with – a misplaced faith in computer models, inability to distinguish between science and opinion, and so forth. But from my own experience I can’t see that this decline in scientific education has been necessary, nor that it cannot be reversed, given the will to do so.
Tom, yes we teach something about scientific method. It is a thread in the K-12 curriculum that is taught in most years. But it is just one of, say, 40 threads, the rest being about scientific content.
Every US state now has regulations, called standards, which specify what content is to be taught in each grade. Many are quite specific, down to the hour level or even finer. There are links to all these standards on our website. My team cataloged all the concepts, by terminology, to build a search engine that estimates the grade level of a document, based on the words being used. The result is a semantic model of science education. The curriculum is packed.
How the content is taught is up to the teacher and the textbook, but we typically teach less than 100 hours a year, so there is not a lot of room for history or philosophy of science. Controversy is normally not taught, because the content is not controversial. Controversies are at the frontier, so reserved for college, especially grad school. Ph.D. students deal in controversies.
Also Tom, I see no evidence that there has been a decline in K-12 science education, unless you mean the number of hours of instruction. I have no data on that. However, in the USA there has been a big push for reading and math, which may have reduced attention to science.
David I only mean to say that in my case, and that of my contemporaries, it proved perfectly possible, as part of a high-school education, to teach the essentials of the scientific method as a precursor to teaching science, and, when teaching science, to do so in such a way as to reinforce the student’s grasp of scientific method. I’m not talking about a deep study of the philosophy of science – the essentials of the scientific method – sufficient to ensure that a child doesn’t grow up prey to every loony catastrophist that comes along, as they do, every few years – can be taught in a few hours, and reinforced by teaching science largely according to how it was discovered.
And I’m not sure I understand “Controversy is normally not taught, because the content is not controversial. “, but my recollection is that my teachers rather enjoyed recounting the controversies of the past – Kepler, Copernicus, Harvey and Lister come to mind, to say nothing of Galileo. Again, the heros of these stories were not merely the humans whose theories triumphed, but the scientific method itself. Present controversies were not shunned, either. In my last year at school, when computing power was starting to be employed by climatology, I clearly remember my physics master telling us (in the context of a discussion on nonlinearity, and having first adumbrated a version of Moore’s Law) that no matter how fast computers got, they would never be able to skilfully predict climate. I think he may have been right.
Tom, I think science is still taught the way you describe, as that is how the standards read in many cases. But teaching about the historic controversies is more of a lesson in progress than in controversy. Controversy is sometimes taught in social studies I think, but I have not looked at those standards.
Stephen Wilde has a new post up on my blog which posits physical reasons why back radiation isn’t going to cause the ocean to warm, all input welcome. I think it is an interesting argument he has put forward, and I welcome expert opinion on it from all sides.
http://tallbloke.wordpress.com/2011/06/05/stephen-wilde-the-setting-and-maintaining-of-earth%E2%80%99s-equilibrium-temperature/
If the air had been heating the ocean and getting the ocean to heat the air more, wouldn’t the rate of heat loss to space have been observably increasing? There again, given the uncertainty of TOA observations, being three times the claimed signal, I suppose not.
Peter Berenyi’s analysis on my blog shows it is likely the TOA balance went negative in the last six years.
http://tallbloke.wordpress.com/2010/12/20/working-out-where-the-energy-goes-part-2-peter-berenyi/
The question is: Is this an indication of a lack of ‘committed warming’ from co2, or the result of lowering the height of radiation to space or reduced humidity in the upper atmosphere due to low solar activity? (shrinking of thermosphere and correlation of 300mb specific humidity to solar activity levels).
Either way, the AGW proponents are caught between a rock and a hard place, because even if it is the latter, natural variation is stronger then they have concluded, and that means less of an effect from co2 than they have claimed.
The sooner they recognise this, the more quickly we can escape from rhetoric at loggerheads, and return to realistic scientific debate.
tallbloke
Thanks for a very interesting article. This makes a lot of sense to me, as a chemical engineer.
But it would be interesting to see how climate scientists react.
In addition to getting some input from Dr. Curry, it would be interesting to see what climate scientists, who firmly support the “mainstream” view, write about these explanations on the role of the ocean in global warming (if you can get them to come down from their ivory tower and read your paper).
Also very interesting were the links to studies linking the shift of the jetstream to the Arctic Oscillation and Arctic air pressures. These appear to show a strong correlation with the “northward” shift of the jetstream from around 1970 to 2001, with a “southward” shift since then (and colder winters across most of the northern hemisphere).
Max
The post of Stephen Wilde adds nothing worthwhile to the standard understanding. Much what he writes is correct and in agreement with what climate scientists have been telling all the time, the rests is just confusion.
It’s true that the oceans act to slow down the warming due to their large heat capacity. This part is common knowledge. The more detailed descriptions of energy transfer between oceans and atmosphere are a confusing set on imprecise assertions that give finally a wrong picture of what’s going on. If the paper would try to present it’s claims as formulas, it would be immediately clear that they are in error, but when they are presented as lengthy imprecise text one can only state that they do not represent the heat transfer correctly.
The greenhouse effect reduces net heat loss from the oceans as it does reduce net heat loss from the continental areas. To reach an equilibrium the oceans must warm. They warm as long as an imbalance exists, and the air near to the ocean surface warms with the oceans.
The net heat loss consists of net IR radiation, latent energy and convection (on the microscopic level also conduction). All these forms of net heat loss are affected directly or indirectly by the greenhouse effect. There isn’t any significant “Hot Water Bottle Effect” other than the large heat capacity of the oceans.
The comments concerning pressure are in the test are without justification. This would also be totally clear, if the paper would contain relevant formulas. The paper is a demonstration on the fact that representing physics correctly without backing by formulas is likely to fail.
Pekka Pirilä
It is good that you, as a firm believer in the “mainstream” (or IPCC) position on climate change, have critiqued the Stephen Wilde paper on the ocean’s role in global warming.
But it would be good if instead of simply saying
and then adding some personal opinions, you would actually refute each point he makes specifically, citing specific studies (hopefully based on empirical data) to support your position.
This is what I hoped I would see from a supporter of the mainstream view, so we could get an idea of just how sound (or unfounded) Wilde’s postulations really are.
[BTW, I believe that is also what tallbloke is hoping for.]
Max
If the paper would be specific enough to even attempt to support its claims, it would be very easy to be specific also on criticism. Now it’s just one of those texts making big empty assertions.
It’s not reasonable to spend time in detailed criticism of papers, which don’t even try to be specific themselves.
I have told, where the errors are in general terms. That’s enough for this text.
This hypothesis has been around for a while and even JC has refuted it here on a thread months ago with the hard facts about the energy balance at the ocean surface, something she knows well enough about, being involved in textbooks. My simple refutation of the Wilde posting is that according to that theory an ocean under a night-time cloud-covered sky would not cool less than under a clear sky. He claims they would cool at the same rate because back-radiation from clouds is somehow selectively canceled by evaporation effects and can’t contribute to the energy budget of the water. This is not right because cloudiness is a major factor in how much a water surface cools, just like for the land. CO2 acts in the same way as cloudiness, though at a more subtle, but long-term, level.
Pekka says:
“The greenhouse effect reduces net heat loss from the oceans as it does reduce net heat loss from the continental areas.”
I would like to see some evidence of that. As my article says, over water evaporation increases and mops up ALL the extra energy in the air from the so called greenhouse effect. When all the extra energy has been used up the evaporation rate stops increasing.
Over land is quite different (assuming the land is dry). Obviously additional surface warming could be expected to occur but then winds increase because the land/sea differential is increased and the oceans cool the land to restore globally the background differential between sea surface and surface air temperature set by atmospheric pressure and the enthalpy of vaporisation.
There is one point which I should have dealt with more clearly. Namely there is always a differential between sea surface and surface air temperatures but the surface pressure shifts to negate any increase or decrease in that differential.
Jim D makes a point about cloud cover which I have in fact considered carefully and discarded.
The thing is that under an open sky more energy in the air increases evaporation whereas, under a cloud evaporation, is reduced because of the reduction of convection and a consequent increase in humidity.
I know that the effect of back radiation is likened (by AGW proponents) to the effect of a passing cloud but for the reason stated the comparison is false and misleading.
Stephen Wilde,
Yes, energy is required to evaporate water but it isn’t used up or “mopped up” as you have stated. It doesn’t just disappear. The energy is stored in the vapour and is released again during the process of condensation.
Energy can only leave the Earth as radiation into space. If radiative conditions are changed, the ambient temperature of the Earth also changes.
Where does that condensation occur? Not at the surface, does it?
Tonto, to ‘mop up’ doesn’t mean to make it disappear. A mop doesn’t make the water disappear either. The water is stored in the mop.
The clouds are not necessarily related to surface relative humidity, so that argument doesn’t hold. Downward IR, whether from clouds or CO2 is indistinguishable at the water surface because the water just absorbs all wavelengths, so if you are admitting clouds have an effect, you cannot separate that from the CO2 effect because IR is IR regardless, and its source doesn’t matter, only its intensity.
JimD
A cloud, any cloud, suppresses convection to an extent linked to its height.
Suppressing convection over water always leads to a humidity increase however small because the lighter water vapour from the evaporation that is always occurring in an unsaturated air mass is unable to rise upward. Thus energy is removed from the surface less fast and the surface warms from recuced cooling and NOT fron increased downward IR from the cloud.
Under an open sky there is no restraint on the upward movement of water vapour (which is lighter than air) so the rate of evaporative cooling is not slowed down at all and in fact it increases because of the additional energy supply in the air which is then available to bring forward the timing of the evaporative event for individual molecules.
Due to the enthalpy of vaporisation each evaporative event which has been induced( or simply brought forward) by only one IR photon actually removes another four photons from the air. The process continues until the IR is ALL converted to latent heat with no residue left over to either heat the ocean bulk or slow down the background energy flow from the ocean bulk.
Water does absorb all wavelengths but only the wavelengths that get past the evaporative barrier will contribute to ocean heat content.
My claim is that you would see immediately that your claims are in error, if you would try to put them as mathematical equations that describe the energy balance of oceans and atmosphere and the other statements that you have presented. Then you would see yourself that the claims are incorrect.
It’s your task to make your claims so precise that their real content is revealed. There is no need for others to try to guess, what you really mean, when the text is not specific enough to tell all details.
That the argument is wrong can be seen from the conclusions, but pinpointing the exact location can be done only, when the argument is made so precise that others need not guess, what you really have in mind. We have seen so many other papers that try to show that the basic understanding of greenhouse effect is wrong (in your case the introduction is correct up to the point, where you start to disagree). The errors are very clear in many of them, but we have seen also several papers following the approach of leaving details incomplete and making it difficult to tell precisely, where the error is. In my view the correct answer to point out this fact, and leave it to that. Unfortunately that doesn’t convince all skeptics, but that cannot be helped, because no other approach is going to convince them any better.
The correct approach is to go through the way these issues are handled in main stream science and do that at the level of equations. If you or somebody else thinks that there is an error, it must be pointed out in the equations. The simplified textual descriptions of the full scientific understanding are not always fully satisfactory. They are mostly compromises between brevity and accuracy. Thus they may not be fully correct, but pointing out such errors doesn’t mean that the same error would be generally present, when the equations are used in real calculations.
I respectfully disagree.
However I have given the matter thought on previous occasions.
All I am describing is the net effect of each process and the composite outcome. That can be achieved with a general overview of the relevant concepts in conjunction with established science.
I accept that it is not a mathematical proof but it does reflect empirical observations.
If, as a mathematician/physicist you see a fundamental flaw then it should be possible for you to express that flaw verbally in a form that the lay readership can follow.
tonto52:
It disappears as far as sensors are concerned. That is the meaning of ‘latent’ heat.
It does indeed reappear at a higher level when condensation occurs and then is radiated faster to space because it is at a higher level.
The tropopause rises a fraction so that by virtue of the lapse rate there need be no temperature increase at the surface.
That rise is insignificant compared to natural changes in tropopause height fron solar and oceanic variability.
So, there is no change in the ambient temperature from extra GHGs. Instead there is a faster throughput of energy to space.
The faster throughput from the surface pressure changes exactly matches the slower throughput induced by the GHGs for a net zero effect.
Thus the equivalence between energy in and energy out is also maintained
There is really no difference in the way that IR radiation is slowed down over land or over the ocean by the presence of GH gases.
Yes if the process of condensation and evaporation does transport the heat to a higher level, it will be radiated into space slightly quicker. Very slightly quicker.
For example if it rises by 1000 m, then 3 microseconds will be knocked off its journey time !
tonto52
Whether over land or over water the effect of IR is the same as you say. However the response of the system is what differs.
Either way the surface air pressure alters to restore equilibria within the system.
Over water the IR is converted to latent heat in vapour virtually instantly and it is mainly the vertical temperature profile that changes.
Over land the air at the surface warms but the horizontal surface pressure profile changes to shift the extra energy over the oceans faster where the evaporative process takes over.
I’ll have to rely on you for the timescale but it is enough. The system responses to extra IR over water are virtually instant because we are dealing with radiative physics which operates at the speed of light.
Thus it is only when the energy has been converted to latent heat (disappeared from the sensors) that the slower mechanical processes that you mention take over.
The only physically observable effect of more IR is a slightly larger sea / land temperature differential because there is a slight lag in the mechanical process of shifting the extra energy from land to sea and a slight change in global surface air pressure distribution from the mechanical process of rising water vapour for a faster water cycle.
However over water the loss of the extra energy to latent heat is instant because it is a radiative process.
To be a little more specific. You represent here arguments that are not correct. You state vaguely that
“the surface air pressure alters to restore the equilibria within the system”.
What do you mean by that? The air pressure is always determined by the mass of the atmosphere and large scale flows of air. Any deviations will influence air flows to restore the balance. That’s the way pressure enters the physics, but I don’t understand, what you are writing about.
The energy flow between ocean consists of several components: solar SW radiation, IR radiation from the ocean, downwelling IR radiation from greenhouse gases in the atmosphere, net evaporation (= latent heat loss) conduction and at the microscopic level conduction. Each of the components is determined by it’s own set of controlling factors like the temperature difference between top layers of the ocean and lower troposphere, relative moisture near the surface, wind mixing in atmosphere and ocean, greenhouse gases, and clouds. There is no specific coupling of on of the factors to another. Thus changing any single one is not compensated by one of the others, but affects all others.
Specifically your statement
“However over water the loss of the extra energy to latent heat is instant because it is a radiative process.”
is wrong.
The greenhouse effect affects the balance by increasing downwelling radiation. Thus one of the components of the energy balance changes. That leads to warming of the top layers of the ocean and influences also the layers a little deeper by affecting the vertical heat flows in the ocean. As the warming occurs simultaneously in ocean and in local atmosphere the convective heat transfer changes only a little. Latent heat loss is likely to increase more although that leads to increased humidity that restricts the increase in latent heat loss. Outgoing IR is increased in accordance of Stefan-Boltzmann law while the downwelling IR is increased both by the increase of the atmospheric temperature and the higher GHG concentration. Clouds affect both solar SW and downwelling IR. Deeper ocean acts as a large heat reservoir, where part of the heat flows leading to a very slow increase of its temperature. This heat flow makes the warming of the top ocean slower that it would be otherwise. The temperature profile of the upper layers of atmosphere is determined by the heat balance at the surface, penetration of solar SW energy, and mixing of ocean layers. Even heat conduction has a role in that at least very near to the skin.
All these factors must be looked at simultaneously to get reasonable results, and it must be done quantitatively. Perfect accuracy cannot be obtained, but fair understanding is achievable. At least it’s possible to determine, which effects are important, and greenhouse effect is one of those.
“the surface air pressure alters to restore the equilibria within the system”.
As is apparent from the rest of my article I am referring to distribution of air pressure and not absolute atmospheric pressure. Hadley cells et al.
“That leads to warming of the top layers of the ocean and influences also the layers a little deeper by affecting the vertical heat flows in the ocean.”
Downwelling radiation appears to have no such effect. It is all absorbed by molecules in the evaporative layer which evaporate sooner than they otherwise would have done until the DLR is gone with no effect on the net energy flow from water to air. It is an instantaneous process at the molecular level.
The persistence of that 1mm deep layer below the evaporative region and 0.3C cooler than the ocean bulk below is the proof. It is present day and night worldwide despite some local temporary irregularities due to surface winds and so not even diurnal changes in solar insolation cannot remove it. Therefore an infinitesimal increase in downwelling IR doesn’t have any effect either.
All the greenhouse effect achieves is to shift the surface air pressure distribution a tiny bit as compared to the effects of natural solar and oceanic variability.
You don’t have to look at everything to ascertain the oceanic equilibrium temperature. It is determined by the atmospheric pressure, the amount of solar shortwave input and the enthalpy of vaporisation. Nothing else. Everything else is restricted to the air above.
Your message is proof of what I wrote before. Your claims are so imprecise and flexible that it’s not possible to discuss on them.
You present just empty rhetoric that cannot be made precise using equations. It’s not possible argue against them, because nothing is fixed and you evade any counterargument using more imagination.
Put the ideas out as equations. If you wish to continue after that, I’m ready.
The evaporative ocean skin layer is cooler than at least a few mm below it during the daytime (b), and cooler than several meters down at night (a), indicating that the evaporative potential at the surface, which is temperature-dependent, is actually less than the evaporative potential of water lower down if the latter were immediately lifted to the surface and allowed to evaporate before any evaporative cooling occurred . Downwelling IR, which is almost fully absorbed within micrometers, and can’t directly heat water 1 mm down, contributes about twice as much energy to the ocean as solar radiation, and so the above data are difficult to reconcile with a strong partitioning of the IR to the surface and the solar absorbed radiation to lower depths. Rather, the two energy sources are well mixed by turbulence and convective mixing (conduction is too slow to have much effect). If the mixing did not occur, the skin temperature (the first few micrometers) would be higher than the temperature of the water warmed by solar absorption at depths of 1 mm and lower.
Is it possible for an ocean whose heat is absorbed only in the top micrometers to have a cooler skin temperature than the water 1 mm and more below, due simply to evaporative cooling? I don’t think so, because the lower layers could only acquire their temperature from the heated skin layer. However, in the real ocean, some heat is acquired by solar absorption at depth. Under this circumstance, could evaporative cooling lower the skin temperture below the 1 mm temperature even though 2/3 of the radiant energy is absorbed inthe skin layer?
Theoretically, I believe this could occur, but not realistically. Ocean surface air is almost 100 percent water saturated, and substantial evaporation and cooling requires constant removal of saturated air by wind and air turbulence. In an ocean surface below completely still air, evaporation would almost cease because of saturation. However, it is the movement of the air that also induces the mixing of the top layers of the ocean – it is a reason the “mixed layer” temperature gradient is shallow. For strong evaporative cooling, very strong air movement is necessary to replace saturated air with air that is still humid but capable of holding additional water vapor.
For all these reasons, it is not a tenable conclusion, in my view, to consider downwelling radiation as anything less than a major source of heat transfer to the ocean. Whether the mixing between solar and atmospheric downwelling back radiation is complete may depend on circumstances, but in most cases, the mixing will almost certainly be sufficient to confer a major role on the downwelling IR.
But if the ocean skin layer is mm’s thick, it cannot actually be very important, when compared to the heat capacity of the column of air above it and the deep water below.
Is not sea water pretty much opaque to IR? According to the science, yes.
Evaporation in the ocean is much more than surface evaporation. The ocean is generally dynamic, churning water by wave action, and constantly changing albedo due to wave shape.
I don’t think any of this helps the idea that small changes in total wattage is going to set off a major climate problem.
And quoting people who cannot even get the null right is not going to help.
“But if the ocean skin layer is mm’s thick, it cannot actually be very important …” – Hunter
The ocean skin layer is what it is: unexpectedly important.
How?
It holds very little energy. It is certainly not going to trigger a CO2 catastrophe.
It is the top of a lot of water.
It has been around since there has been water. It seems to work just fine,a nd CO2 is not going to make it behave differently.
For the purposes of AGW promotion it seems to be a nice diversion.
How? The same way it always has. CO2 raises the temperature of the skin layer. If didn’t, this would be a very different world, starting a very long time ago.
JCH,
CO2 is not magic energy.
Everything that hits the surface layer at the right energy levels raises the temp of the surface layer.
If the surface layer was responding to the increase in CO2 by changing anything significantly- thickness, heat content, pH, viscosity, ability to evaporate, etc. we might have something to talk about.
Instead, we have yet another stage prop for know fear mongers.
More like a religious artifact than a stage prop
I never said it was magic. You added that nonsense. Additional GHGs result in a hotter skin layer. GHGs causing a hotter skin layer is a big reason this joint is habitable. Suddenly it’s supposed to stop because you’re a one-note reactionary. I don’t think so.
The skin is nothing more and nothing less than a very thin of layer of water between the atmosphere and the rest of ocean. This thin layer is essential, because with the exception of SW radiation all other important energy and material flows between the ocean and the atmosphere (or space) involve physical processes in the skin layer. Only the SW radiation penetrates through the skin layer.
The skin layer would be of little significance, if it would not interact strongly also with the rest of the ocean through convective mixing, conduction and diffusion. Thus it’s necessary to understand, how the skin layer interacts with atmosphere and radiation as well as, how it’s connected to the rest of ocean. Still it’s worthwhile to study specifically the skin layer, because that’s where the evaporation and IR absorption/emission occur. Concerning evaporation and convection the skin layer on the side of the atmosphere is equally important, but it’s transparent enough to IR to pass it almost unhindered to/from rest of the atmosphere.
The skin layer is totally capable of absorbing and emitting IR essentially as a black body and balancing the energy fluxes through its interaction with the rest of ocean and the atmosphere. Nothing in the properties of the skin layer acts to prevent the influences of greenhouse effect and changes in the concentrations of GHG’s.
The skin layer is in general slightly colder than water immediately below, because the net energy flux from the layers below is upwards. Those layers are heated by solar SW and they must get rid of this heat and that must go mainly up. Thus the skin is cooled by the atmosphere (mainly through evaporation) as well as net IR and heated by ocean below. More GHG*s reduces the cooling by net IR and lets the ocean (both skin and layers below) warm to return to balance.
Pekka, without GHGs, the idealized skin layer would be cooler than it is with GHGs. If the skin layer were cooler, more heat would leave the oceans over a given time span. Agree?
Yes, I think I said it at the end of my previous comment.
Fred Moolton said:
“Ocean surface air is almost 100 percent water saturated, and substantial evaporation and cooling requires constant removal of saturated air by wind and air turbulence. In an ocean surface below completely still air, evaporation would almost cease because of saturation.”
There is your error. Water vapour is lighter than air so it creates and enhances convection. There is always a constant removal of saturated air by convection even in the complete absence of wind. Indeed it is convection that results in wind.
Once the movement of air has started then any increase results in a further increase in the evaporation rate and the faster evaporation rate induced by more wind removes energy from the surface fast enough to prevent downward mixing.
This is not novel stuff invented by me. It was established science 30 years ago but appears to have been forgotten.
You imply that a container of air would separate by molecular weight so that water vapor rises to the top and oxygen would sink below nitrogen with CO2 forming a layer at the bottom. This does not happen even in still air, except perhaps on very long time scales.
If the molecules would be noninteracting, each gas would have its own barometric distribution that would not be influenced by the other gases. That distribution is approximately exponential (for isothermal atmosphere exactly exponential, but with non-zero lapse a little different). The rate of decrease of density of each component with altitude would be proportional to the molecular weight. Thus every gas would overlap over the whole atmosphere, but heavier gases would be more prevalent at low altitudes.
The real gases do interact, and that leads to much more uniform distribution of concentrations. The convection mixes all components without being influenced by molecular weight, but diffusion in a stratified atmosphere with no convection would very slowly change the composition towards that of noninteracting molecules. As I wrote above the gases would not even then be layered on top of each other.
Stephen – I don’t think this makes any sense. Consider a static column of still air above an area of ocean. If the warm air near the surface is saturated, it can’t exist in equilibrium with colder unsaturated air at a higher altitude, because the humidity would quickly become distributed throughout the air column by convective mixing unless there were some place for the water vapor to escape outside of the column. There would be no room for additional water from the ocean. For drier air to replace humid air requires horizontal advection of drier air via wind and turbulence, and for much drier air to be involved requires substantial wind. All of this is consistent with observational data indicating that waves are the norm for the ocean and that waveless, quiescent, wind-free ocean surfaces are a rarity.
We can’t conclusively state that solar and downwelling back radiated IR are completely mixed, but given ocean wind and waves, they are certainly mixed well enough for us to conclude that the downwelling IR probably contributes more to ocean temperature than solar absorbed radiation.
If you disagree, you are welcome to cite quantitative data on strong evaporative ocean surface cooling as the primary fate of downwelling IR without significant wind or waves. It must be strong enough for the very large IR incoming flux to be responsible for a cooler skin layer than the underlying water rather than a warmer one. Please cite wind strength (or lack of it), water vapor replacement rate and its source, latent heat transfer rates sufficient for the observed low skin temperatures, and the fraction of ocean surfaces where you believe these phenomena can be found.
An additional source of information is derived from ERBE and CERES observational data reported in the 2009 BAMS paper by Trenberth, Fasullo, and Kiehl. Tables 1b and 2b indicate that for the oceans, absorbed back radiation is about 350 W/m^2, while latent heat transfer is only about 100 W/m^2. Even if all the latent heat transfer came from the back radiation and none from absorbed solar radiation, which is very unlikely, we would still find that most of the absorbed back radiation was re-emitted from the ocean as IR radiation rather than latent heat, signifying that most of it came from absorbed ocean heat, at a level exceeding the solar absorbed radiation.
These are averaged values, and so it is conceivable that in some limited areas, the balance is reversed, but overall, the data show that more back radiated thermal energy was captured in the ocean than was dissipated by evaporation without making ocean temperature warmer than it would otherwise have been.
It is one of humanity’s most interesting characteristics that if one doesn’t wish to believe something then the imagination can produce any number of reasons why it cannot be so.
That applies to both AGW proponents and sceptics so rather than me having to counter a catalogue of desperate imaginings let’s cut to the chase.
Is there an empirically demonstrable equation that shows that there is any energy left over from the enhanced evaporative process when downward IR hits molecules at the ocean surface ?
The enthalpy of vaporisation (a proven and well established equation in itself) shows that for every unit of energy required to induce evaporation five units of energy are extracted from the local environment for a large net cooling effect.
How is it proposed that there be any surplus left over to heat the local environment ?
Physics is a science that has developed combining very successfully empirical observations and theories. It has produced equations that describe heat conduction, evaporation, interaction of radiation with material, convection and all the relevant understanding that is required to get answers to your questions. The validity of all that knowledge has been validated in innumerable ways. The results have been published in textbooks written by scientists spending much effort to make the presentation as readable and comprehensive as possible.
Your questions fall nicely in what these textbooks describe. The details of the phenomena are complex enough to make the full description also complex – far too complex to represent fully in comments of this thread.
The practical situations cannot be analyzed with full perfection, but some simplifying assumptions are always needed. That doesn’t, however, mean that the general features would not be well known. The answers that you have received here are more or less correct comment based on that extensive physical knowledge (there are some minor errors, but not significant enough for me to start correcting them). They are good enough to tell, where your most obvious errors are. Repeating the same comments in slightly different words is not worthwhile.
When a problem like the one you consider appears, the normal approach is to check, whether the well known and validated physics can be used. In this case it clearly can. Additional measurements may be needed to fix the details, but they are not necessary for the general description. For that textbook physics and generally available observational data is enough.
It’s pointless to ask for specific experiments to confirm each peace of general understanding separately, but additional measurements are needed to find out details. Such measurements are done all the time and they are used by the scientists to make the picture more precise.
“It must be strong enough for the very large IR incoming flux to be responsible for a cooler skin layer than the underlying water rather than a warmer one.
But that is exactly what we do see. The cooler layer is 1mm deep and 0.3C cooler. Worldwide and persistent despite local temporary disturbances.
So kindly address my previous question and deal with that bit of data too.
Stephen – Your questions have been answered both in terms of theory and with a reference to observational data, all demonstrating that downwelling IR absorbed by the ocean skin layer contributes far more to ocean temperature than to evaporative cooling, and contributes more than absorbed solar shorwave radiation. At some point, you will need to confront the understanding that what seems to be a pet theory of yours can’t be reconciled with the facts. What you do with that realization will be up to you, because most of the rest of us won’t care, and readers of these exchanges will be able to make their own judgments if they aren’t already familiar with the physics. I suspect you know what they will decide.
Neither of my points have been addressed here.
If the answers exist please direct me and readers to them.
i) The enthalpy of vaporisation (a proven and well established equation in itself) shows that for every unit of energy required to induce evaporation five units of energy are extracted from the local environment for a large net cooling effect.
How is it proposed that there be any surplus left over to heat the local environment ?
ii) But that is exactly what we do see. The cooler layer is 1mm deep and 0.3C cooler. Worldwide and persistent despite local temporary disturbances.
There is also an error here as to the definition of the skin layer. Some say it is the interactive molecules at the top whereas some say it is the cool 1mm deep layer above the ocean bulk.That cool 1mm deep layer lies below the interactive layer and the only heat accretion to the ocean from downwelling IR occurs in individual molecules in the interactive layer which then evaporate faster than they otherwise would have done to negate any net effect on the ocean bulk.
“Is there an empirically demonstrable equation that shows that there is any energy left over from the enhanced evaporative process when downward IR hits molecules at the ocean surface?”
Stephen – I think you may have an inaccurate mental picture of evaporation. If you heat water, you increase the fraction of molecules capable of escaping from the liquid to the vapor phase, but for this increase in molecular kinetic energy and evaporation to occur requires the water to become hotter rather than colder, which means that the molecules left behind in the liquid phase are also more energetic than before. A strong enhancement of evaporation requires the water to become much hotter from absorbed energy. You can’t cool water by heating it – i.e., by adding thermal energy to it (you could probably do a home experiment to check this).
On the other hand, you can increase both evaporation and cooling by removing water vapor faster from the overlying air, thereby reducing its partial pressure, as Alex Harvey notes below. In theory, very rapid airflow to replace saturated air with low humidity air could permit energy absorbed in the skin layer to be rapidly dissipated mainly via evaporation, and would be signified observationally by a significant departure from saturation in ocean surface air. That could only occur, however, if the absorbed energy were not immediately mixed into underlying water, but that mixing is what occurs with significant airflow. For a visual image of this, remember that the IR is absorbed within a few micrometers, but that even a small ocean wave in a calm ocean is orders of magnitude larger in the perturbation it creates – that is why mixing is so rapid.
The above explanation in qualitative in nature, but the BAMS reference I cited provides quantitative confirmation that IR absorption goes mainly into keeping ocean temperature higher than it would be otherwise.
Regarding skin layer temperature, it is cooler than below, but the 1 mm temperature is warmer, to an extent consistent with convective mixing – Ocean Temperature.
I truly don’t believe, Stephen, that this is one of the aspects of climate change that is subject to much uncertainty in terms of the general effect, although quantitative details involve a modeling of complex interactions, as Pekka has indicated.
Forgive me for my intemperance Fred, but you are talking complete bollocks.
And you know this instinctively. You sweat to cool down. More energetic water molecules evaporate, leaving the remainder at a cooler temperature. You feel cooler.
You also know this from the windchill factor. Or from feeling a sheet drying on a washing line.
Your statement
‘but for this increase in molecular kinetic energy and evaporation to occur requires the water to become hotter rather than colder, which means that the molecules left behind in the liquid phase are also more energetic than before’
is simply wrong.
You may be veyr distinguished in whatever field you practice, but your knowledge of simple physics and chemistry is very poor …and often wrong-headed.
Latimer – Thank you for your comment.
It’s just not possible to teach a full course of physics in a blog discussion. When any part of the well known basics can be questioned – and is indeed questioned, I don’t see real alternatives for giving up.
It’s also not productive to try to guess, where someone has his own gaps of knowledge. The better way is to learn the well established physics and the correct description of the processes in that way, but as a started, a blog discussion is not the right place for that.
It’s pity that so many people believe that their own thinking based on little knowledge of physics would be more valid that the understanding of all experts. The scientists are not that stupid or incompetent.
By the above comments I don’t claim that there were no open issues or that no errors would remain in climate science, but the errors are definitely not in the basics. Every proof that CO2 cannot warm through greenhouse effect is certainly wrong, but the strength of the effect is not equally uncontroversial even among competent climate scientists.
I’ll take that as a ‘no comment’ as regards my points then.
Stephen,
I think that you are arguing a case for how evaporation works from what causes boiling to occur. This I guess this from the role that you give to surface pressure.
Boiling, a condition whereby bubbles of vapour occur in a water column, is governed bythe internal pressure of the water and that is related to the pressure at its boundaries. That maybe atmospheric pressure or mechanical pressure. Provided this pressure is less than the vapour pressure of the water, which is governed by temperature, boiling will occur.
Evaporation, a condition whereby water molecules depart from a surface, is governed by the partial pressure of water vapour, not the atmospheric pressure.
Providing this partial pressure less than the vapour pressure of the water evaporation will occur.
The atmospheric pressure at the ocean surface does prevent the ocean boiling but it does not govern evaporation. It is the partial pressure of water vapour, not the atmospheric pressure that influences evaporation.
Alex
“Boiling, a condition whereby bubbles of vapour occur in a water column”
Only if the heat source is from below. If the heat source is from the top it is exactly the same as evaporation.
Stephen,
That is just wrong. Even wiki (http://en.wikipedia.org/wiki/Evaporation) agrees that they are two different forms of vaporization:
“Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid.”
It is not due to external heat sources. A liquid boils if its internal pressure is lower than its vapour pressure, at which point bubbles of vapour are produced in the water column.
You stop a liquid from boiling by increasing its internal pressure by any means, you stop a liquid from evaporating by increaseing the partial pressure of vapour at the surface.
Here is a video of water boiling due to lowering and keeping the atmospheric pressure below the vapour pressure:
http://www.youtube.com/watch?v=ta73_bQ1d2A
At around 40 seconds bubbles occur in the water column, there is no effective external heat source.
Alex
Of course one can make water boil without a heat source if one reduces the pressure.
However we are considering scenarios where the pressure stays the same and energy is added from above.
It is perfectly possible to add energy so fast from above that evaporation from the surface becomes boiling at the surface.
In that situation there is in principle no difference. It is just a matter of degree.
Having considered carefully the comments of those who have set out objections to my essay I think I have determined the critical issue giving rise to those objections.
As regards radiative processes it is necessary to raise the entire system temperature in order to achieve an increase in outward radiation. Thus if something (a ‘greenhouse’ gas for example) slows down the transmission of energy through the system it is necessary for the equilibrium temperature to rise to regain energy budget balance.
However when evaporative processes are involved it is NOT necessary to raise the entire system temperature to achieve an increase in outward radiation. Instead all that is necessary is for there to be a redistribution of energy within the system.
Thus is it entirely reasonable to suggest that the radiative characteristics of greenhouse gases can be entirely offset by an evaporative response without the system equilibrium temperature needing to change.
My readers will note that as regards the top down solar effects I contend that it is not radiative effects that dominate but chemical processes in the upper atmosphere that respond to solar variability.
I contend that as regards the bottom up oceanic effects it is not radiative effects that dominate but evaporative processes.
Thus the issue of radiative balance is a mere distraction yet much of the climate industry concentrates on that alone to the exclusion of chemical and evaporative processes.
Stephen, Your views have clearly developed, but there are still differences between our views.
What happens as the immediate consequence, when GHG’s are increased, is warming of the skin layer of the oceans, because that’s, where the IR has it’s effect (there are also changes in the atmospheric absorption). That extra heat influences all other energy flows of the skin layer: It increases outgoing IR radiation, it increases convective heat transfer, it reduces the heat flux from below, and it increases the evaporation. All these fluxes change and the sum of the changes is equal to the increase in absorbed IR. There is no way that only part of the flows would be affected, it’s certain that they all change and all change in the direction that balances the additional incoming IR.
The energy absorbed by one water molecule is in almost every time distributed to the surrounding water as heat. It’s exceptional that it would just kick one molecule out of the liquid to the atmosphere, and even when that happens the likelihood that the molecule is soon scattered back to the liquid is significant.
Obviously ALL the cooling mechanisms do increase when extra IR is absorbed by molecules in the interaction layer (not the 1mm deep layer below it).
If energy goes into radiation, conduction, and convection then clearly it will not be available to suopport enhanced evaporation.
The enhanced evaporation mops up the rest of the available energy for no change in the background energy flow from ocean to air.
The energy absorbed by one molecule may well be partly transferred to another molecule before evaporation occurs but then both molecules will evaporate earlier than they otherwise would have done and each molecule that evaporates takes 5 times as much energy out of the local environment as is required to induce that evaporation.
Quite simply there is nothing left over to heat air and ocean so as to alter the equilibrium temperature of either.
The temperature increase is localised to the molecules in the interacting layer and does not influence equilibrium temperature, merely energy distribution within the system so as to change the rate of energy transfer out to space.
So the enhanced evaporative process offsets the radiative consequences of more GHGs.
No. The temperature increase is not localized so much that your conclusions would be justified at all. The extra heat spreads very rapidly to the surrounding water. Your claim is pure speculation, which you have not justified by real arguments just made blanket claims, and it’s indeed wrong.
Even the infrared penetrates the water to that extent that the absorption does not occur at the surface, but a bit deeper, when looked at the microscopic scale. The average penetration depth is several micrometers based on this data. Each cubic micrometer contains 30 billion water molecules. Thus even 1 micrometer inside means being covered by a huge number of other molecules. Thus the molecules that absorb the radiation cannot evaporate without distributing the energy to billions of other molecules. The absorption is thus not localized to few molecules that can evaporate immediately, but distributed effectively to the whole skin layer.
Every water molecule that receives extra energy evaporates earlier than it otherwise would have done.
Each such molecule pulls five times as much ehergy out of the local environment than is required to induce evaporation.
Your contention that there is any energy left over is pure speculation.
Pekka – I save most the stuff you write, and everything you write about the ocean skin layer. My understanding of the skin layer has increased substantially since you started commenting on the subject many weeks ago. Thanks.
JCH, if you want to know more then try this:
People here are referring to that layer 1mm deep and 0.3C cooler than the ocean bulk as the skin layer. That is the usual definition of it but that is not where the evaporative action happens.
Above that skin layer is the ‘Knudsen layer’ where all the evaporation takes place and its depth is the distance that IR radiation penetrates the water surface i.e. hardly at all.
The Knudsen layer is neither water nor air but a haze of interacting molecules of both water and air.
Every water molecule in that Knudsen layer is affected by the incoming IR and each such water molecule is in the process of being accelerated towards an earlier evaporative event than would have been the case without that IR.
Each water molecule affected, when it evaporates, takes five times as much energy out of the Knudsen layer than the energy put in to induce that evaporative event.
The evaporative cooling within the Knudsen layer soaks up the incoming IR as fast as it arrives with no effect on the temperature flow from the water below in the ocean skin or on the temperature of the skin itself.
The molecules in the Knudsen layer obviously become warmer but the ocean skin below it does not warm and nor does the air above.
The incoming IR is therefore transferred straight to latent heat in the air via the evaporative process and can only affect the Earth’s energy budget when it condenses out again at a much higher level where the extra energy from the downward IR is accelerated off to space by radiation from the upper atmosphere.
Evaporation grabs the IR, whether natural or human, makes it vanish from view as latent heat, invisibly transports it upward and then releases it in a form and in a place from which it is ejected from the system faster than it would otherwise have departed.
So if the so called greenhouse effect slows down the exit of energy to space by bouncing downward IR back to the surface then the evaporative process soaks it up and throws it back up again at a speed equal to the initial slowing down for a zero net effect overall.
Since the evaporation creates more water vapour in the air and water vapour being lighter than air then all the IR can do is accelerate the water cycle and the sole remaining physical manifestation of that is a shift in the surface air pressure distribution.
So the IR has a climate effect but it is infinitesimal compared to the changes in surface pressure distribution that happen naturally.
The Knudsen layer is very thin, far too thin to absorb significantly IR. The layer is on the side of gas and its thickness is at most few mean free paths of the gas. In case of air the mean free path is 0.068 micrometers. Thus the Knudsen layer at most 0.2 um of gas and contains less water than 0.0001 um of liquid water. That’s irrelevant for IR absorption.
Almost all IR penetrates deep enough to be covered by billions of molecules of liquid water.
Nice try, but totally wrong.
Nice try Pekka, but wrong.
The depth of the Knudsen layer is enhanced by the very limited penetrative depth of IR. I have seen somewhere that IR does not get past one micron.
Anything that gets past the Knudsen layer is solar shortwave radiation that does indeed add to ocean bulk heat content but that does not include downward IR from the atmosphere. It does include some near IR from the sun. If you were correct then increased IR from the atmosphere would reduce the temperature differential between the ocean skin and the ocean bulk (0.3C) but it does not.
If you look at the gradient towards cool at the top of the oicean in the diagram that you linked to previously you will see that the gradient in that topmost region is the same day and night. It follows that if the huge changes in insolation between day and night do not change the gradient then a downward atmospheric IR flux will not do it either.
If you wish to pursue that point you need to provide evidence to the contrary.
There are two other points you have not considered:
i) Although downward IR does add energy to water molecules it can never warm them beyond the temperature at which evaporation will occur. That temperature has been preset by atmospheric pressure and humidity and cannot be changed by increased IR input so IR cannot raise the surface temperature higher than it would be without it.
ii) As regards clouds the fact is that each cloud rides along on its own bubble of higher humidity. Thus, when a cloud passes over, the evaporation rate reduces and the water surface temperature rises. That is completely the opposite effect from more IR input under an open sky. In that latter case humidity does not rise because water vapour is lighter than air and will rise freely by convection with less humid air being supplied by horizontal winds all the way back to the nearest land mass. Thus the frequent analogy between clouds and more IR is utterly false.
Stephen,
You are the one that claims that generally accepted knowledge is wrong. The burden of proof is on your side. It’s of no use that you invent proposals of possible errors as long all those proposal are without merit and strong supporting evidence to counter all the data that has led to the present understanding. Your imagination is no match to the widely understood and well verified knowledge of physics.
I’m not inventing anything, just telling things that I have learned as a physicist. Physics has not been the most central field of work for most of my carrier, but I’m a physicist by education and I was 10 years full time theoretical physicist and I have lectured numerous courses of physics. Even after my main field of work moved towards energy engineering and economic issues, I have quite often been involved also with physics. When I encounter issues, where I don’t know enough of the details, I check, whether I can combine my basic knowledge of physics with additional information from books or net sources to form an understanding that I can trust myself. Most of the comments on physics related issues here and elsewhere are based on this process and I try to avoid commenting, when I’m not confident that my knowledge is on solid ground. Sometimes it turns out that I make errors in this judgment. When that occurs, I correct my statements as I did concerning my comments on the paper of Annan and Hargreaves (that was a good reminder of the risk of arrogance).
I gave a link to the strength of absorption of IR in water. The link was to a picture in Wikipedia, but that doesn’t matter, as it’s based on empirical measurements. You can dig, where it comes from, if you have any doubts on its correctness. It tells that the attenuation coefficient is around 1000 cm^1, which means that the average penetration depth is close to 1/1000 cm = 10 um. That means that the absorption occurs typically at a depth of around 30000 molecules looking directly up. From that depth the energy can not get to the surface without being distributed to billions of molecules.
If you disagree, present numbers or equations instead of repeating unjustified qualitative statements. As I started this message, the burden of proof is on your side, as you contradict common knowledge.
So you cannot demonstrate it then ?
You cannot show that there is any surplus energy left over after the enhanced rate of evaporation has done its work ?
As far as I know the things I am saying were common knowledge over 30 years ago so it isn’t me who is making a new claim.
Calls to authority are not adequate and I’m sure you are expert in your field (energy engineering and economic issues) but to me you seem to have a blindspot regarding evaporative processes at the air/sea interface.
Being a physicist does not give you authority on areas of physics outside your professional speciality.
If the change from day to night cannot alter the temperature gradient in the 1mm deep cooler layer then IR cannot do it either. If what you say were true the gradient must vary or disappear under the influence of increased IR whether from the sun or from atmospheric downwelling.
However it does not and you cannot say why it does not nor do you accept the implications. You just prefer to ignore inconvenient facts and defer to the ‘new’ assumptions of an immature climate science which in many respects fail to comply with basic physics and observations.
Actually, Stephen, it’s not that hard to show that there is surplus energy left over after evaporation. Here’s how.
The downwelling infrared global 24/7 average is generally accepted to be on the order of 320 W/m2. This is the same as 1E10 joules per square metre per year.
Now, it takes 2270 kilojoules to evaporate one kg of water. This means that the downwelling IR is enough to evaporate 1E10 / 2.27E6 ≈ 4,450 kg of water per square metre year …
Water is about a tonne per cubic metre. So that means that there is enough downwelling IR to evaporate about 4.5 metres of water around the entire planet per year.
But we know that evaporation must equal rainfall, and the global average rainfall is only about one metre per year.
So even if only downwelling IR led to evaporation, there’s still a lot of surplus energy left over after all evaporation is accounted for. Of course it’s worse than that because some evaporation is from solar energy. And that of course means that there’s even more surplus IR …
I say that surplus IR warms the ocean and the land … where do you say that surplus IR is going?
w.
Thanks for your contribution Willis. At least you are addressing the point and not blustering, going off at a tangent or calling upon authority.
However: note that the enthalpy of vaporisation is 1 unit of energy to induce evaporation and then the change of state takes up 5 units of energy (of which 1 was the original input) then the reverse when there is condensation higher up. A ratio of 4 to 1.
Then you say that 1 metre of water per year appears to shift the energy equivalent of 4.5 units of evaporation or a ratio of 4.5 to 1.
I metre of water shifts the energy that would be required to induce 4.5 metres of evaporation IF the balance of the energy required were NOT taken from the downwelling IR but in fact the downwelling IR is just where it comes from. So that is apparently where the ‘surplus’ IR is going. Straight back out to space in an escalator called latent heat.
Near enough don’t you think ?
Now I could have misunderstood something. Have I?
Did you take the enthalpy of vaporisation into account in your calculation ?
“I say that surplus IR warms the ocean and the land … where do you say that surplus IR is going?”
Why do you not say that it warms the air for an increase in the speed of the water cycle as per your thermostat hypothesis ?
It is at that point that our propositions mesh together save that you focus on the equatorial convective belts and I focus on the air circulation patterns worldwide.
Steven, I haven’t a clue what you mean when you say:
However, yes, indeed, I did take into account the latent heat of vaporization (also called the enthalpy of vaporization). So your whole claim is meaningless. Let me go through the numbers again.
It takes about 2,200 kilojoules to evaporate 1 kg of water at 100°C. At about say 20°C (ocean temperature) it takes about 2,450 kilojoules to evaporate 1 kg of water.
A joule is a watt-second. One watt over a year (1 W-yrt is 365.254 days/year * 24 hrs/day * 60 minutes per hour * 60 seconds per minute gives us 31,600,000 watt-seconds, or 31,600 kilojoules.
Divide that by the 2,450 kJ required to evaporate 1 kg, and we see that in a year, one watt will evaporate about 12.9 kg of water.
Now, downwelling IR is usually taken to be on the order of 320 W/m2. Thats enough to evaporate about 320 W/m2 * 12.9 kg, giving us 4,130 kg of water evaporated per square metre of surface, or 4.13 tonnes/m^2.
A tonne is a cubic metre. That means that you are claiming that the globally the IR is evaporating 4.1 metres of water per year … which is in total contradiction to the facts.
Now, please note that your objection (you thought I had neglected latent heat of vaporization) was entirely incorrect.
So, what is your next explanation? Or are you ready to admit that all the downwelling IR that strikes the ocean can’t all be evaporating water. Estimates of global evaporation are about one metre of water (depth) per year. There’s enough IR to evaporate about four metres per year … so where is the rest going?
w.
Some of the energy is used to move ocean currents, Florida current transport alone is up to 150 Sv.
Hello Vuk.
I would have though that solar shortwave input would have done most of the heavy lifting but the point in issue seems to be whether IR from the atmosphere whether solar, natural or human induced makes a significant difference.
Willis has made a point that seems valid and I await his further response.
“From that depth the energy can not get to the surface without being distributed to billions of molecules.”
From whatever the depth is upwards all the affected molecules will either evaporate sooner than they otherwise would have done or will pass on their extra eneregy in an enhanced upward flow to cover the energy shortfall created by enhanced evaporation at the surface.
So even if your distinction between the Knudsen layer and the penetrative depth of IR were to be true (but I don’t think that it is) the same outcome would follow.
If just one molecule evaporates sooner than it otherwise have done it pulls up from below 5 times as much energy as was needed to provoke the change of state. So however you cut it the process of enhanced evaporative cooling deals with all the extra energy from the IR. By my account it comes from within the Knudsen layer and above. By your account it comes from within the Knudsen layer and below. Either way the outcome is the same.
Basic established physics at least half a century old.
Reading through this thread and the piece by Stephen has cause me to ponder on how it can be that people are at odds over how stuff works. One might consider that we must have different realities, and it is my prejudice that we do.
A little thinking about the problem of evaporation lead me quickly to the conclusion that I had never put it to bed. I had thought about it neither hard enough nor long enough to have built a cognitive model that was both consistent and complete. Consistent in the sense that my thinking on this problem did not conflict with my thinking on other problems, and complete in the sense that I had considered all the most wild and whacky extensions of the problem that I could dream up.
When I think of reality, I am thinking about cognitive models. I have models that relate to the real world and ones that are more abstract. My reality, not limited to the real world, extends to mathematical models that may have many components that have no real world counterparts. Spaces with an infinite number of dimensions, the complex plane, etc., things that form part of my reality yet to shop for is problematic. I consider that our sharing of a common reality is unlikely and may be impossible.
What bothered me about evaporation is that I had no clear idea as to how rates of evaporation could be modelled. The problem at hand regarding the ocean surface is not straightforward and whereas I could draw some general conclusions from arguments concerning equilibrium states; determining the rates, and which aspects of the real world might be their principle governing factors, eluded me. We have some idea about the annual evaporation rates from the ocean surface, it is of the order of 1 metre/annum, but that is a poor guide to what may be happening at a particular place and time. Digging into my box of tricks I can see a role for energy balances, maximal evaporation rates into dry air, diffusion rates through the boundary layer, vapour pressure above the boundary layer, etc., but no idea as to the dominance of each.
Most worryingly I had no idea about the maximal evaporation rate into dry air, beyond modelling this as being the evaporation rate at all other times, even at equilibrium, where thay are modelled as a dynamic balance with the evaporation and condensation rates equating. So I could model the problem by considering just condensation rates.
My model of what it is to be a gas informs me as to how many molecules per second per unit area would impact the surface for any given temperature and pressure. I Have no means of knowing whether all such impacts would be inelastic, where the molecule absorbed by the surface, or that some may be elastic, where the molecule bounces back from the surface. The first case would maximise the condensation rate and hence give a maximal value for the evaporation rate. My model can extend to both circumstances even though only one may correspond to reality. To decide which being a matter for experimentation.
So my model, my reality, includes the case whereby condensation works optimally, consists of inelastic colisions. This case is problematic, to the degree of lying down in a darkened room for some hours. In the absence of elastic scattering, in the case where the gas is only water vapour, there was no obvious means of equilibrating the temperature of the gas phase and the liquid phase should they differ. Without such a mechaninsm the temperature of the molecules that were evaporating (what ever such a temperature means) needs be the same as the temperature of the gas phase and hence the same temperature as molecules that were condensing. For this not to be the case risks violation of my model of thermodynamics due to extracting energy from the implied temperature gradient.
For my model to be consistent, the molecules that evaporate, each singularly, and without knowledge of each other, (spot the cognitive model) must somehow embody the same temperature as the surface of the liquid. I have to confess that it was not obvious to me how this would be the case. Now in what sense does a stream of molecules departing from a surface have a temperature. It would be handy if their kinetic energies had the same statistical distribution as the gas at the same temperature. What is required is the ratio of the rate of evaporation of molecules with different energies correspond to the Boltzmann distribution. Now in my model this must be a property of the liquid phase as it is true at the moment of departure. Hence I have deduced something that needs to be true of energy distribution of the molecules of a liquid.
At this moment, this is part of my reality, it is part of my cognitive modelling. So far it is consistent, as complete as I have been able to make it, and has implied something concerning what it is to be a liquid, another subject I have not thought about hard enough.
Providing my models are consistent, and not knowingly incomplete, they comprise a reality and are in that sense true. Whether they are an adequate description of the real world is another matter. From my point of view, they represent a reality that is true even if it is neither the same as anothers reality, nor applicable to the real world. I give them truth by limiting them to what is consistent and testing them for cognitive completeness. They would be true if evaporation had never been observed or it didn’t occur.
By this description you may well conclude that I am possessed of bizarre and deluded mentality likely the product of a misspent youth, and you may well be correct. I do consider that reality being a product of imagination risks real world delusion.
Given that we have but one real world but conflict as to how it works and what effects can be surmised I must conclude that we have different realities, I think this be inevitable and not a bad thing.
Science as it is commonly considered, constitutes a narrow reality, a subset of our models that is commonly held to be useful. It is a communal activity. A process built on communication and education designed to limit thought to achieve a purpose. But if it addresses a need to identify a communally held subset of our differing realities; it fails. We are not like that. We progress, not just in response to new evidence but by new thought. New thought demands new and differing realities.
I characterise the climate debate as a clash of realities. A failure of science in that sense given. I am not surprised that this should happen but I am surprised by the scale of it. If it is true of climate what else might it, must it, be true of. Viewing reality as a coping mechanism for the tribulations of the real world, it seems likely that the scale of the divergence may be enormous, given we each construct our most conducive reality. Considered thus, I may conclude that it is likely impossible and possibly undesirable to reconcile the differences. Education amounts to tinkering with anothers reality. There is something inherently coercive in the process. Perhaps the most I can challenge is by way of asking whether we all have sufficient self-doubt, and if not, why not.
Stephen’s piece, whatever else I might have thought about it, did cause me to question what I thought, and why I thought it. That process has caused me to imagine a greater and richer reality. It has led me to speculate on the nature of what it is to be a liquid. It has inspired much new thinking and for that I am grateful. It has exposed me to a different reality and being one that is obviously sufficient for his needs should contain fresh insights. It is not such a simple matter that it turns on whether or not it is a view that I find applicable to the real world. That it works for someone implies that it may be consistent with a body of knowledge and not found incomplete, it constitutes a reality, and thus is content rich. In particular it has led me to consider the differences in effect between solar and infrared heating and the importance of this in a world where they may have been varying in opposing ways of late.
Interacting with people who have a very different reality may vary from irritating to downright disturbing. For the most part we may keep these differences under wraps lest they cause disquiet. This is a discretion lacking in climate debators and lunatics each of which seem to let it all hang out.
FWIW my reality and science did concur on the following points:
On the condensation of molecules (it may not be explicitly stated but total inelastic absorption is implied in Eq 2):
Irving Langmuir: (1917) “THE CONDENSATION AND EVAPORATION OF GAS MOLECULES”
My speculation on the statistical kinetics of liquids (Eq 3 onwards):
Penner “On the Kinetics of Evapoation” (1952):
http://authors.library.caltech.edu/16923/1/18_Penner_SS_1952.pdf
Now if I had only thought about it 100 years ago!
The nature of my approach to such problems puts me at a distinct disadvantage in terms of the debate. Mine is too slow, it requires arguing about details; and by the time I might be ready, the debate has moved on with seldom a look in its rearview mirror. I also suffer from doubt which needs to be overcome with much thinking. I cannot see that much can be achieved without considerable time dedicated to equations. Equations are such hard edged little devils and one gets them wrong at ones peril. Without sufficient mathematics little can be demonstrated, and he who waves arms most furiously may be seen to prosper. If it turns into a battle of attrition I can but withdraw on health grounds. Ultimately it may come down to which side is least capable of questioning its reality. To be certain of an argument no matter how incomplete or inconsistent is always a less expensive position.
Alex
Over the past few years New Scientist and several other science magazine have frequently wrote about the mysteries of water. As the article begins No liquid behaves quite as oddly as water.
H20 is so common, and well studied but when it comes to many water molecules interacting together you need the fastest supercomputers in the world, like ‘Thunder’ at Lawrence Livermore National Laboratory, for analyses. When someone says the physics of water has long been established, you have to be careful what they mean. There are still disputes in science to how water work. Add to that, that the ocean is not pure H20. The same goes for the complexity of the atmosphere, many molecules interacting is not easy to model or understand.
Gee Alex, remember this:
“how can a forcing driven by longwave absorption and emission impact the ocean below since the infrared radiation does not penetrate more than a few micrometers into the ocean?” – Peter Minnett
It strikes me as sad that this question needs answering or even asking. – Alexander Harvey
Yes I do, albeit vaguely.
I am still of the same view for I believe I meant it literally. It saddens me. That the “how” should be in doubt I interprete as ignorance of, or disregard, for the following effects: conduction (resulting from molecular collisions sometimes modelled as mediated by phonons), electromagnetic radiation (mediated by photons), mass transport (convection, eddy diffusion). Each of these address the “how” question.
These effects transport energy, and the rate of energy transported increases as the temperature gradient increases downwards direction. Raising the temperature at the surface or lowering the temperature of the ocean will promote an increase in the downward flux or reduce the magnitude of a pre-existing upward flux.
I do not think that Stephen doubts these points. He is making a specific argument that seems to amount to pleading a special case for a novel photo-evaporative effect. An effect that is conjectured to remove heat from the surface that exactly balances the incoming IR photon flux and hence leaves the surface temperature unchanged.
I do not think that Stephen doubts that to increase “ordinary” evaporation requires the surface temperature to be increased. He talks of “enhanced” evaporation which I take to be some sort of quasi-quantum effect although this is not stated.
I think that there is enormous scope for arguing passed each other, if he is considering a novel effect.
This should be contrasts to the previous example of the “how” question which is addressed by what are commonly considered to be, well known, usefully modelled effects. I do find it sad if the “commonly considered to be” part is not true. I may have got Stephen wrong but he may well understand the same physics albeit differently. If his argument is soley about the existence of a novel effect then arguing about other matters is of little benefit.
Now do I believe that such a novel effect is remotely plausible? Yes I do.
Do I think it would result in the balance described? No I don’t.
Do I believe that such an effect could be detected? Yes I do.
The last point needs dealing with in detail. I would be a little surprised if no such effect occurs, but I wouldn’t initially look for it in the infrared, I would look for it in the ultraviole where individual photons have the energy to remove molecules from the surface. This is however, quite close to the energies required to dissociate the molecules so there would be competing effects. Were I to look for anything I would look for the result of both effects the ejection of charged ions suchs as H2O+ as these might be detectable.
As to the second point, I do not think it would achieve the required balance and I suspect that this can be proven. Initially I would consider the additional evaporation rate that is implied by the “enhanced” evaporation . If it turned out that this was too big, e.g. would exceed the known rate of ~1m/annum, then this would be fatal. Here it needs to be noted that it would be the entire downward IR flux that comes into play not the excess or net flux.
Alex
Others can check this, but I think the energy per 15 micron photon is only about 20% of the energy needed per water molecule to provide the latent heat for vaporization, so the photons would have to go into some kind of heating first, not direct evaporation.
Yes I think that figure is correct, in the near UV the photon energy is about 10 times the per molecule requirement. So if there were to be an effect I would look in the UV first but somewhat higher up at around 60nm where the absorption for dissociation occurs.
What one might find I cannot tell, but evaporation seems to have been studied mostly as an aspect of chemistry and chemists have a long history of precisely measuring process rates that tends to the obsessive. This argues against the effect being measurable.
Alex
Phew, Alex. A well thought out comment that I agree with.
Different minds will interpret the same data differently whilst both may be honest and intelligent.
As to whether my piece is wholly correct remains to be seen but it is a description that seems to fit a lot of real world data and in these days of proposed catastrophic man made climate consequences the subject I covered is at the heart of the entire issue.
As you seem to appreciate (whereas Pekka does not) the science of the sea/air interaction and the role of the different wavelengths is not clear and settled.
Furthermore you amply and eloquently point out the vast number of variables involved the net interactions of which (over time) are not currently accurately represented by any existing equations.
I am merely trying to make a start by creating a conceptual overview that links long established basic physics with the changes in various climate phenomena that we are only now becoming able to monitor with modern sensing techniques.
Others can develop the equations when we have enough data.
In the meantime the ‘reality’ which I think I see does deal with a lot of actual real world changes in a rather neat fashion. I suspect there is more to it but I do not think I am on a completely wrong track.
A problem with discussing details at the level, where much is unknown is that people like Stephen interpret it to mean that even basics would not be known and that they are free to invent their own theories and to pretend that they are more correct than common knowledge.
I have described in my messages many issues that are not so well known and stated that fact explicitly, but emphasized also, what is known much better. The scientific knowledge is a complex combination of things known very well (and the basics of energy balance I have described here belongs to that) and things known with lesser as lesser certainty ending to speculations on issues, where the proper knowledge is lacking.
An essential part of the professionalism of physicists is having a feeling of, how the general picture can be formed correctly and what is known reliably on that basis. Beyond that a detailed analysis is needed and that requires very often data that is not readily available, but must be obtained through further experimental work.
“Beyond that a detailed analysis is needed and that requires very often data that is not readily available, but must be obtained through further experimental work.”
Agreed. Let’s have the necessary data. The basics of the energy balance at the sea/air interface is not well known.
I have been discussing that basic part, where this detailed data is not necessary.
As said by more or less everybody participating this debate (and certainly taken into account by me from the beginning when writing my comments) the surface phenomena are complex and water is a quite exceptional substance. Therefore the details are still a subject of research.
But nothing in the above is contrary to the fact that the basic features influencing the energy fluxes are well known and taken into account in main stream science.
To clarify a bit, what is known well and what is more complex.
First I tell, what I mean by the skin layer: For me it’s a layer that is just thick enough to take care of the phenomena that don’t influence directly the rest of ocean. The limiting phenomenon is IR emission and absorption as it penetrates strongly about 10 um and weakly a bit more, but not much more than 100 um or 0.1 mm. Thus the thickness of the skin layer can be taken as anything from 0.1 mm to a couple of millimeters. A good value to have in mind might be 200 um (0.2 mm).
1) We know that energy is conserved. Thus the heat fluxes to a thin skin layer must always be very close to balance, as the heat capacity of a thin layer is so small and the gross heat fluxes are large (in total hundreds of W/m^2).
2) The main heat fluxes to the skin layer are
– with ocean below heat transfer in form of convection and conduction. Conduction is a significant part of the whole, because the skin layer is so thin and temperature gradients there rather large.
– with nearby atmosphere mainly evaporation and condensation. Both occur continuously involving a large gross energy exchange, but the net evaporation (or net condensation) is much less that the gross exchange
– there is also some heat conduction across the surface related mainly to N2 and O2 molecules bouncing from the surface
– IR radiation couples the top tens of micrometers of ocean with atmosphere, where the lowest 100 m absorb and emit much of the radiation that originates or ends in the ocean skin layer. Part of the radiation penetrates further in the atmosphere or escapes to the space.
3) The solar SW penetrates typically a few meters in ocean water, but a small fraction reaches much larger depths. A small part of the energy of SW may result in increasing the average temperature of the ocean water, but most of it moves ultimately up to the skin, from where it’s released to atmosphere and space.
4) Approximate average numbers are (these are from Trenberth et al, but the numbers describe the general magnitudes even, if the exact values are not trusted as accurate). Values are in units of W/m^2
– solar SW absorbed in oceans 167.8
– IR absorbed by the skin layer 343.3
– IR emitted by the skin layer 400.7
– net evaporation 97.1
– sensible heat (convection in atmosphere) 12
This leaves 1.3 W/m^2 for heating the atmosphere, but this is certainly the number with largest relative uncertainty. This means also that the net heat flux from below to the surface is 166.5 W/m^2 on the average and this is released to the atmosphere as net evaporation and net IR of 57.4 W/m^2.
The above values are averages. The local and temporal variations are large.
The net evaporation is the difference between gross evaporation and gross condensation. The amount of gross evaporation depends only on the temperature of the extreme skin layer of ocean and on the surface roughness influenced by winds. This is so, because gross evaporation is formed by individual molecules getting loose from the liquid. This involves an loss of kinetic energy as the molecules of water attract each other and breaking the attractive bond takes energy. The gross condensation depends on the moisture and temperature of air on the atmospheric side of the skin. Here the Knudsen layer is an important factor. When a water molecule get bound to the liquid, the bonding energy is released as kinetic energy of the molecules. The mixing of air near the surface is very important in removing moisture from the atmospheric side of the skin, and affects thus the rate of net evaporation. At microscopic distances from the ocean surface the air is almost saturated by moisture and its temperature is very close to the ocean skin temperature, but the moisture and temperature gradients may be large in that thin part of the atmosphere. The net evaporation is controlled also by these gradients and the gradients by mixing with the atmosphere further from the surface.
All the above can be expressed by equations. These equations are not the full description of all detailed processes, but they tell, how different energy fluxes, temperatures and atmospheric moisture are interlinked. The coefficients of these equations are not known precisely, but well enough to provide a good general view of what happens. From the point of view of this discussion the essential conclusion is that every subprocess is influenced by temperatures of ocean and atmosphere at different distances from the surface and the subprocesses in turn influence the temperatures. The subprocesses do not interact much in other ways. (E.g. increased IR from above warms the whole skin layer, the warmer skin layer both emits more radiation and has stronger evaporation. Its increased temperature also reduces heat flux from below. All these effects combine to reach balance.)
Ocean absorbtion of solar irriadiance is spectrally dependent eg sim
http://lasp.colorado.edu/sorce/images/instruments/sim/fig01.gif
Another way of showing this fact is in this picture that I linked in one of my earlier messages
http://en.wikipedia.org/wiki/File:Water_absorption_spectrum.png
Here we see that around 600 nm only 2% of light is absorbed in a meter of pure water. but for most of IR the absorption is more than million times stronger.
pure water amazing
In ocean the difference cannot be as large as the relative influence of impurities is largest, when pure water is most transparent.
But we knew already from everyday experience that pure water is very transparent for visible light, while sea or lake water is never as transparent.
No you are guessing.Bio optics is a distinct science Monin devotes an entire book to this in his volumes on the ocean.
Andre Morel is one of the leading practioners in this fielld eg ocean colour.
Suprisingly the clearest waters on the planet are the so called purple patches in the transect east of Rapanui.
http://www.obs-vlfr.fr/proof/ftpv/biosope/prj_life/others_papers/accepted/Morel_et_al_LO_07.pdf
Corresctio Suprisingly the clearest waters on the planet are the so called purple patches in the transect north west to east of Rapanui.
http://oceancolor.gsfc.nasa.gov/cgi/browse.pl?sen=am
Amazing things are observed.
In the areas of clearest waters the heating by solar SW seems to extend at significant intensity to several hundred meters depth.
What I had really in mind, but didn’t say explicitly, is that for IR the absorption by water molecules is so strong that even major impurities have little effect. When the main molecules absorb very efficiently that determines the result. Those observations tell that the natural water can be so clear that the situation is nearly the same even for the visible light and near UV.
One more point related to the size of loss of kinetic energy in every molecular evaporation event. The rate of such events is essentially proportional to exp(-E/kT) where E is the energy required for the molecule to get out of water. Thus the events are the more rare, the larger E is. Increasing the temperature of water reduces the strength of this dependence on E. Therefore gross evaporation is controlled by the temperature.
There are significant complicating details in what happens at and very near to the surface, but the general principle holds and has been confirmed empirically.
Pekka,
Thank you for your detailed reply and the time you havre spent compiling it.
I will give it some time to sink in and assess whether it changes my understanding.
In the meantime Willis Eschenbach made a good point which I am currently directing my attention to.
Hello Willis. I have given some thought to your good point that down welling IR on the face of it provides enough energy to evaporate 4.5 metres of water whereas actual average global precipitation is only 1 metre.
The point to note is that water vapour contains more than 5 times the amount of energy as compared to water for the same sensible temperature.
Then I see that it only requires 419KJ to heat water to 100C (where it must vaporise at existing atmospheric pressure) from 0C.
Most ocean water is well above 0C so in practice it will take less than 419KJ to vaporise it.
So the energy cost of evaporating that 1 metre of rainfall is relatively small. Far less than the figure you mentioned.
However, once that water evaporates at a relatively low energy cost it has to acquire the extra energy it needs from somewhere and I contend that most if not all of it comes from the down welling IR.
Now in vapour form the energy content is as you say but not all the IR has been used to create evaporation. A small portion induced the evaporation but the rest was mopped up by the evaporative process.
So it is perfectly feasible to propose that 1metre of rainfall when converted to water vapour is enough to carry the same amount of energy as would have been required to evaporate 4.5 metres of water if the energy shortfall had not come from the down welling IR.
The fact that the 4.5 to 1 ratio is not quite the same as the enthalpy of vaporisation could be accounted for by other factors such as the solar contribution.
Does that make sense?
2.5 MJ/kg is the latent heat of vaporization, which is the relevant number here, as Willis says. This can be seen the energy to separate water molecules from the fluid bonds.
Pleae ignore the above post since I see the flaw.
Hello Pekka,
I’ve had a go at understanding your comments but cannot see anything that invalidates what I have said previously (in my humble opinion).
I’ll pick out a few of your comments and provide my responses so that you can then make your objections clearer to me.
i) ” First I tell, what I mean by the skin layer: For me it’s a layer that is just thick enough to take care of the phenomena that don’t influence directly the rest of ocean.”
That is fine by me. Presumably you mean the Knudsen layer where all the evaporative activity takes place or perhaps just a bit deeper. You can’t be meaning the 1mm deep layer that is cooler than the ocean bulk below because that layer does not seem to be directly affected by what goes on above.
ii) “Thus the heat fluxes to a thin skin layer must always be very close to balance.”
Agreed, otherwise events in that layer would affect the air above and the ocean layers below.
iii) “but the net evaporation (or net condensation) is much less that the gross exchange”
I agree with that too because other processes are in operation as you say but I would say that evaporation holds the balance due to the huge amounts of energy that can be moved by a phase change of water.
iv) “The solar SW penetrates typically a few meters in ocean water, but a small fraction reaches much larger depths. A small part of the energy of SW may result in increasing the average temperature of the ocean water, but most of it moves ultimately up to the skin, from where it’s released to atmosphere and space.”
Agreed but I would add that the rate of upward transfer is dictated by the equilibrium temperature of the bulk ocean set by the level of solar input, atmospheric pressure and the energy value of the enthalpy of vaporisation.
v) “The net evaporation is the difference between gross evaporation and gross condensation. The amount of gross evaporation depends only on the temperature of the extreme skin layer of ocean and on the surface roughness influenced by winds.”
We depart slightly there because all the means of heat loss by the oceans including evaporation will be determined primarily by the equilibrium temperature of the ocean. The temperature of the skin affected as it is by events above the water is a secondary factor.
vi) “At microscopic distances from the ocean surface the air is almost saturated by moisture”
That is as may be but the vapour rich air is constantly being moved away by convection and wind because water vapour is lighter than air. The gradients do not control the net evaporation. It is the net evaporation that controls the gradients. Thus the combination of net evaporation, upward radiation convection and conduction combined create that cooling gradient worldwide day and night so that the ocean bulk is always overlain by a 0.3C cooler layer 1mm deep which lies below the layer where the evaporative processes occur.
vii) “(E.g. increased IR from above warms the whole skin layer, the warmer skin layer both emits more radiation and has stronger evaporation. Its increased temperature also reduces heat flux from below.”
Here we come to the crux.
I do not agree that the increased energy (not temperature because it cannot get warmer than the temperature required to initiate evaporation and the sea surface is always already at that temperature beneath an unsaturated atmosphere) in the interactive layer reduces the heat flux from below. You do accept increased radiation and stronger evaporation but seem not to have factored in the energy hungry nature of evaporation which needs five times as much energy to sustain it as it needs to induce it at current atmospheric pressure in an unsaturated environment.
Willis Eschenbach had a good go at countering that point but if you look at my response you will see that I do not agree and why.
Can you deliver a coup de grace to stop me wasting my time if I am wrong?
The Knudsen layer is on the atmospheric side, not on the side of water, but a very thin part of the atmosphere. It contains very little water compared to the skin layer (perhaps 0.01%, but the value depends on, how each layer is defined more precisely).
The evaporation is not energy hungry in the way you continue to think. Each single molecular process involves indeed relatively large energy in molecular thermal comparison, but that doesn’t lead to your results. The energy is actually many times larger than the energy of an IR photon, it’s at the level typical for photons of visible light. Only a tiny fraction (one in millions) of molecules at the surface happens to get such a kick from its neighbors thermal motion. One IR photon could not help much even if it happened to be absorbed really at surface.
But to continue: Each case of evaporation is energy hungry at the scale of thermal phenomena, but exactly this same energy hungriness makes the net evaporation to be so slow that it’s effect doesn’t dominate everything. It doesn’t do it at present GHG concentrations, and it doesn’t dominate the changes due to additional IR from more GHG’s.
Stephen, Pekka, and all.
I am puzzled by the Knudsen layer, or at least by the wording in the short wiki piece:
“From kinetic theory, it can be derived that if liquid is in contact with vapour, there is a small layer where the phase is between liquid and vapour. This region, several mean free path lengths thick, is called the Knudsen layer.[1]”
Unfortunately I haven’t found a free copy for ref [1]:
“Kazuo Aoki, Claude Bardos, and Shigeru Takata (2003). “Knudsen Layer for Gas Mixtures”. Journal of Statistical Physics”
and fear that it may have been a passing remark or a very open interpretation.
This is why.
The layer thickness varies with the mean free path, and is a small multiple of it, it does not include terms relating to chemical bonding , indicating to me that we are talking about a gas phase but one with some peculiar properties.
I consider, or speculate, that if net evaporation is taking place there will be a difference between the partial pressure above the layer and the vapour pressure of the surface, and it is likely that there is also a temperature difference.
As the gross evaporation rates and gross condensation rates differ we have a region close to the surface where the kinetic statistics of the two flows differ. E.G. the upwelling flow at a lower temperature specifically a lower value of kT than the downwelling flow. A region where it would be unsafe to use bulk gas statistics and where such concepts as diffusion would need to be considered in terms of a gas that doesn’t have the usual statistical properties.
The definition of the layer thickness is compatible with my notion that only after some multiple of free path lengths would the two stream (up and down) equilibrate.
So we are talking about a gaseous layer but one that may be far from equilibrium where standard techniques for calculating temperature and pressure gradients do not hold. (see quote below)
I think the thickness of the layer is two or more orders of magnitude greater than the molecular diameter taking it well beyond the reach of intermolecular forces.
I cannot see that my view is compatible with the notion that the phase is in doubt once a molecule is more than a small multiple of its diameter above the surface a region orders of magnitude thinner than the Knudsen layer.
Here is the informative quote I found:
“In the present study, we consider the situation of small Kn, i.e. weakly rarefied flows, which is typical of the flow regime in the above applications. In general, for a weakly rarefied flow, almost the entire flow field can be described by hydrodynamic equations except a thin Knudsen layer immediately close to the wall (e.g. catalytic walls or CVD substrates) [4]. Despite its small thickness, which is of the order of the mean free path, the Knudsen layer plays an important role in determining the surface reaction rates. The reason is that, in many hydrodynamic problems in the presence of surface reactions, the reaction rates are determined based on the assumption that the gas molecules striking the wall have a Maxwellian distribution. However, the Knudsen layer causes deviation of the distribution from the equilibrium Maxwellian distribution [5, 6]. Therefore, the non-Maxwellian distribution of gas molecules at the wall should be taken into account.”
“Role of the Knudsen Layer in Determining Surface Reaction Rates Based on Sticking Coefficients Peng Zhang and Chung K. Law”
Which was presented to:
“2007 Fall Technical Meeting
Eastern States Section of the Combustion Institute
University of Virginia
October 21-24, 2007”
http://lcg.princeton.edu/publications/conference-publications/zhang-role-of-the-knudsen-layer-in-determining-surface-reaction-rates-based-on-sticking-coefficients.aspx
This is a long way from the wiki quote which conjures up the prospect of some sort of part gas part liquid froth.
Any thoughts.
Alex
Alex,
Checking most easily available literature, it’s indeed obvious that Knudsen layer is that part of the gaseous phase that is so close to the liquid or solid surface that molecules have a significant likelihood of immediate (past or future) contact with the surface. This is just equivalent to saying that the distance from the surface is less than a few mean free paths.
The proximity of the surface affects in many ways the properties of the gas. In particular the shape of the velocity distribution of the molecules may differ from the Maxwell-Boltzmann distribution. All chemical reactions and in particular the evaporation are certainly affected by these surface effects. Also on the side of the liquid, the molecules that are close enough to the surface to “feel” it behave certainly somewhat differently from the bulk of the liquid.
The interaction with IR may differ from that further from the surface, but the effect cannot influence significantly the overall energy balance, because IR passes so easily through such thin layers. Only a very small part (something like 0.01%) can interact in this layer, because there are no microscopic mechanisms that could lead to much stronger interaction. It’s not necessary to know much about the complex details of these phenomena to be sure that their effect on the energy fluxes is much less than 1% of total.
You, Jim D, and me, we all have stated in our earlier messages that the energy of evaporation is much larger than that of typical thermal radiation photon. It’s actually equal to the energy of a photon in the very near IR almost visible as red light. Such wavelengths are practically nonexistent in thermal radiation from a source of lower temperature than 400 C or so (they get common at temperatures, where the material is visibly reddish, when observed in darkness). Due to the huge number of molecules at the surface some of them happen even so to collect enough energy from their neighbors to break the attractive bonds and evaporate. As I have written before, the rate of such events depends only on the temperature of water and roughness of the surface, which determines the ratio of the surface area as determined at the microscopic level to that measured at macroscopic level. The IR absorption influences the process through the temperature of the whole skin layer. It may have some barely observable additional influence from those cases, where the absorption occurs where close to the surface, but this effect cannot be large due to the rarity of such absorption as well as the relatively low energy released in each case of absorption.
Concepts like “rare” get a different meaning, when the total number of molecules is as large as it is. Thus the evaporation of 1 m in a year corresponds to about 7 molecules in second from the area occupied by a single molecule of water at the surface, but 7 molecules in second is extremely little compared to the number of collisions this same molecule has had during a second with its neighbors. Every molecule of air has about 10 billion collisions in a second, and the number is several times larger in liquid, although defining, what is collision is less clear in liquid. The ratio of 7 to 50 billion is of the same order of magnitude as exp(-E/kT) = 9×10^-9 for E the energy of evaporation and T=288K.
A surface phenomenon like evaporation requires a sequence of processes
– heat transfer to the surface of liquid water (otherwise the water would cool and rate of evaporation be reduced)
– the release of molecules from the surface determined by the temperature
– the removal from the evaporated molecules further in the atmosphere (otherwise net evaporation stops as the rate of condensation gets equal to rate of evaporation)
Any of these subprocesses may be the principal limiting factor and the particular circumstances change often the limiting factor. (All steps influence the outcome, but very often a single one dominates.)
Whilst understanding most of the points made here I still have some questions but rather than using up more of others’ valuable time here I’ll go and see if I can work them out first.
Thank you for the courtesy and consideration shown.
Pekka’s post has tempted me back but I’ll try to be brief.
Pekka said
“The IR absorption influences the process through the temperature of the whole skin layer. ”
I assume that you mean the 1mm deep layer that is 0.3C cooler than the ocean bulk below.
Is there any evidence that increased IR from GHGs in the air reduces the temperature differential between that layer and the ocean bulk?
Not specifically 1 mm, perhaps only 0.2 mm or as much as a few millimeters. In any case a layer thin enough to reach rapidly an almost uniform temperature through the whole layer. That allows for sizable temperature gradient even within the layer, but not such a huge gradient that would lead to significant temperature differences. At the very surface (within one or two intermolecular distances) it’s possible that defining the temperature is not possible due to strong dynamic processes, which could be described better by non-equilibrium thermodynamics. In that case I mean the temperature just far enough from the surface to make it well defined.
I don’t know, how well the fine details have been studied empirically, and I have not tried to get comprehensive knowledge on the empirical research that has been done. Measuring changes in the temperature differential are certainly very difficult or even impossible in real world situations. Some laboratory simulations of the typical conditions would certainly be possible, but I don’t think than they would be considered particularly interesting from the scientific point of view. Knowing more on the temperatures of different ocean layers of the real oceans is of interest for many reasons, but the natural variability is so large that determining the average change in the differential may well be beyond reach. It perhaps slightly more realistic to determine the changes in the average energy fluxes through the sea surface. Then the balance must be filled by the heat flow within the ocean.
Yes, I have found that the fine details are very vague and that there are attempts in progress to improve measuring facilities.
It is important from a scientific point of view because IR must reduce that temperature differential between skin and bulk if it is to reduce the upward flow as proposed by AGW theory.
I notice that earlier you did say that you thought the skin layer did warm (thus reducing the differential with the bulk) and that as result the upward energy flow slows down so that ocean heat content rises.
However you now seem to suggest that that has not been empirically verified which is as I thought.
I agree about the huge scale of natural variability from internal ocean processes (and possibly also solar effects on the upper atmosphere) that in my view swamp the IR effect anyway.
I will need to adjust my ideas as to the relative powers of evaporation, radiation, convection and conduction in light of Willis’s figures but the net outturn does still seem to be that the surface air pressure distribution changes in response to more energy in the air from increased IR rather than the ocean heat content increasing.
That surface pressure redistribution being insignificant as compared to natural variability as you seem to accept.
I have tried to make it clear that it’s not at all necessary to verify empirically every result. Physics is a mature enough science to allow for extensive reliable knowledge on what is going to occur in many new situations, and for physicists to know, when they have strong reason to trust such conclusions and when they are more speculative that good knowledge. All physics textbooks are teaching those capabilities and most textbooks cover only areas, where the understanding is strong and stable.
All basic physics has been verified empirically, and so is the capability of physicists to perform as I described above. Everything is linked to empirical knowledge, but all details are not checked one by one – and need not be, unless they are of particular importance.
Concerning the energy balance of oceans and atmosphere there is a lot of empirical data of various kinds. They are compared with theoretical expectations. This tells in general terms, how well the physics is known, and that tells also, how well we can trust our understanding of the important processes. If the theory would fail seriously on some point, that would lead immediately to conflicts with existing observations in a way that would be totally obvious. In this indirect way we can trust that conclusions of the type that I have presented, are not far off. (One person can certainly make all kind of errors, but many people are involved in related work, and serious errors would certainly be observed.)
Once more: The knowledge is not complete, many details are not known, but the general picture is known. I’m not an expert on these issues, but my general knowledge of physics allows me to feel certain, when I avoid going too far in the details.
Well the ocean heat content is not going along with the idea that more GHGs reduce the energy flow from ocean to air but it is early days and the degree of natural internal ocean variability seems to be larger than initially acknowledged so it is still open to debate.
The reduction in the rate of energy flow from ocean to air is mostly dependent on Fourier’s Law but there is the prospect that the effect of that Law can be offset by the combined responses of evaporation, upward radiation, convection and conduction from ocean to air. I may have weighted it too heavily in favour of evaporation alone.
I have likened it to the flow of water in a river and tributary where they join. The volume of flow downstream increases but the velocity of flow from upstream does not decline.
The temperature gradient from ocean bulk to skin layer would operate the same way as gravity along the course of a river.
So at the air sea interface the background upward flow of energy from ocean to air would be joined by the energy flow from surface to air so as to increase the total upward flux without reducing the flow from water to air.
That appears to me to be consistent with basic physics but to resolve it we seem to need an empirical measurement in that particular case.
Analogies work only as far as their internal dependences are similar. After some pondering I noticed that this one works better, than I first thought.
When the flow from the tributary increases suddenly that influences also the main river upstream of the point, where they join, but in most cases cannot influence the total volume of flow from the main river for long. It’s easy to figure out, why that’s the case, but as long as the flow remains high the water level remains higher than it would be otherwise.
The analogy is true even so that the influence of the tributary to the rest of the river can be thought in terms of the changes in water levels in the whole river system. Higher water level at the join increases both the cross sectional area and the slope of the river surface downstream of the join. Upstream it reduces the slope but increases the cross section. The volume upstream is forced by flows from so far upstream that the influence is minimal (there is some influence unless free falling waterfalls separate river sections from each other, but the influence is usually too small to be observed). Even here the analogy works, but at a different time scale. The initial reduction in the flow from the main river doesn’t last long unless there is a big reservoir or flood plain just above the join, but in the ocean we have the analog of a huge reservoir (or perhaps more closely with a long section of river with an extremely small slope). Therefore the increase in the temperature of the skin reduces the heat flux for a long period. The temperature of the rest of the ocean starts to increase, but does it very slowly. Finally after a very long period (possibly thousands of years) the ocean has reached a new equilibrium. It’s not warming any more and all the heat of solar SW is lost again trough the surface.
That assumes that there is indeed a warming of the skin rather than a seamless introduction of the additional upward flow from the surface upwards.The lead up to the ocean/air interface could operate like a tributary joining a steep river bed with little or no scope for pooling or spreading.
Some empirical evidence would be helpful.
However I have elsewhere suggested that if there is any reduction of energy flow from ocean to air as a result of more human sourced GHGs then it would take millennia for the effect to become measurable due to the vast buffering effect of the ocean builk.We are agreed on that point.
AGW proponents cannot have it both ways. Either the energy from extra GHGs stays in the air and shifts the surface air pressure imperceptibly or it is offset by a reduction in energy flow from the oceans in which case we have a massive buffer.
So, either the extra GHGs in the air have no effect at all or any effect they do have will be deferred for so long that we have plenty of time to get past the coming global population peak into a period of managed (hopefuly) reduction to a sustainable level and to modify our energy technologies to wean ourselves off fossil fuels (but not before renewables become a lot more economic).
But these are exactly things that are known well enough as part of the well established and verified knowledge of physics. We know that the gross rate of evaporation is controlled by the temperature and the net rate by that and properties of the atmosphere. It’s not necessary to check that again all over the oceans. We know that the conduction is proportional to the temperature gradient. We know that IR penetrates several micrometers in water. All this is known. We know also that the heat capacity of the ocean is huge.
You started without finding out, what physicists have known for years, and you just guessed, what might happen. That way the likelihood of being right is very small, and the well known physics tells that the likelihood is actually zero.
You know much better than me on that so I take it on board.
It follows that your contention is that on the basis of established physics there must be a reduction in the temperature differential where the skin is in contact with the ocean bulk below as a result of any increase in GHGs.
Personally I would have thought that there would be a change in the temperature differential where the ocean skin is in contact with the Knudsen layer above but not necessarily where it is in contact with the ocean bulk below.
Referring back to the river analogy it is the skin that would be the pool or reservoir and not the ocean bulk. The energy flow from ocean bulk to skin would continue undisturbed just as the river flow a certain distance upstream would be undisturbed.
But as you say I’m just guessing without the benefit of the knowledge you have.
Stephen,
Everybody has basically two alternatives. The first is to learn so much about the present scientific knowledge that making own judgments is on good basis. That is a major effort and takes usually years of work. The other is to learn just enough to get a possibility of forming views on whom to trust more and whom less and then accepting views that are supported by those who are likely to know the subject better and tell honestly, what they think.
The third alternative of making guesses without sufficient background knowledge is very unlikely to succeed.
In large majority of cases professional scientists try to be honest. That’s true also for climate science. I believe that real fraud is as rare (almost, but not quite absent) in climate science as it’s in other fields of physical sciences, but there are more reasons for bias in fields as politically heated as climate science is. That has led to the result that many scientists don’t want to discuss scientific uncertainties in public, and trying to prevent the leakage of such thoughts to public they may be excessively careful even within the climate science community. It’s all too common that scientists think paranoically, how their results might be used as support for policies that they do not believe as wise. They do that in good will, but that doesn’t prevent the approach from being detrimental to science. Whenever this kind of behavior is observed, the mistrust of science increases. That and other biasing factors mean also that people like me, who have basically strong trust in science, have difficulties in finding out, what is the real state of knowledge in the most difficult parts of climate science like the construction and use of large climate models.
Good advice Pekka.
For people like me who cannot possibly spend the time to learn the vast range of scientific disciplines involved in climate science (I doubt that anyone can do it) and who have lost trust in so many experts yet have a lifelong interest in the subject the only road left open is to form one’s own opinions on the basis of what knowledge we have and then test them against better informed people in places like this.
I get a ‘bloody nose’ from time to time but so far the lessons I have had to take on board have not been fatal to my entire climate overview but have required adjustments.
The comments from you and Willis will help me refine things but the main point I am grateful for is confirmation from someone as senior as you that even if the oceans can be made to warm from more GHGs in the air the timescale is so long that catastrophic anthropogenic global warming is a non starter.
If the oceans do not warm then again it is a non starter because the necessary shift in surface air pressure would be so small.
I trust that readers here will take that on board and pass on the word.
Having rerad my original article in the light of Willis Eschenbach’s comments I found as folows:
i) I never claimed that evaporation dealt with ALL downward IR.
ii) I specifically stated that increased convection radiation and conduction were also involved and that they reduced the energy available for evaporation
iii) Therefore the implication was that evaporation exerted a ‘mopping up’ function efficiently removing any remaining IR after those other processes had taken their share.
I should have made that more explicit and asked for evidence that there was any IR left over to warm the oceans after ALL those processes had done their work. I will rectify that for the future.
Accordingly it does not matter for my hypothesis that the level of downward IR is enough to evaporate 4.5 metres of water yet in fact evaporation only mops up 1 metre of water.
Simply put, the evaporative process will deal with any downward IR not dealt with by the other processes and if that only needs to be 1 metre out of a potential 4.5 metres then so be it.
As regards Pekka’s objection I take that seriously and It seems wise to accept his assertion that downward IR may well get past the Knudsen layer and into the skin but I still have a niggling doubt as to whether that matters.
In the face of a general upward flow of energy through the skin it is not necessarily the case that the rate of flow at the point where skin is in contact with ocean bulk need be reduced.
I will keep an eye out for new data on that issue before I adjust my propositions.