by Alan Longhurst
“Never before in 1000 years the Atlantic Meridional Overturning Circulation (AMOC), also known as the Gulf Stream System, has been as weak as in the last decades“.
This announcement from the Potsdam Institute for Climate Impact Research was headlined recently in my morning newspaper in France (and in dozens of others elsewhere) as being the result of the anthropogenic ‘rechauffment climatique.’ We were warned that the consequences would include more rigorous winters for us over here in Europe. Whoever wrote that cannot have critically examined the old adage that it is the Gulf Stream that brings Western Europe a comfortable maritime climate, because folklore it turns out to be…
Rahmstorf and his colleagues in Potsdam have hammered away at this issue for a long time now. Their new paper is brief, presenting bundles of proxies intended to demonstrate that flow of the Gulf Stream has weakened in recent decades, and so put the equable maritime climate of Europe at risk.
But this a misleading oversimplification: in reality, the Gulf Stream is no more than a short segment of the wind-driven Subtropical Gyre of the North Atlantic and, as Wyville-Thompson wrote in 1871 concerning the Gulf Stream “after leaving the Strait of Florida…at about 42oN a large portion…turns eastward and southward and, eddying around the Sargasso Sea, fuses with the northern edge of the equatorial current and rejoins the main circulation.” 
So the North Atlantic Current which continues towards Europe and eventually enters the Arctic Ocean carries just a very small fraction of the water that had previously passed along the Florida coast as the Gulf Stream, together with slope and shelf water received from the seas around Newfoundland and the Gulf of Saint Lawrence.
Long-term change in SST is difficult to quantify, but the evolution of sea surface temperature indicated by the HadNMAT2 archive for the northern oceans is shown below. Although the authors of this study suggest that these data support “existing estimates of global warming” it is difficult to imagine that they contain a progressive anthropogenic signal: the data are dominated (i) by the consequences of the numbers of ships at sea (ii) by the imprecision of the early bucket-over-the-side observations and (iii) by the advent of automated free-drifting instrumentation. These observations do not support the progression of the North Atlantic temperature/circulation indices that were offered by Potsdam to support their proposal for an exceptional slowdown in North Atlantic circulation during approximately the same period.
And the pattern of SST changes on much smaller scale obtained by coastal sampling at lighthouses, tide gauge sites, and so on suggests that southeast coast of the US washed by the Gulf Stream has not, in fact, warmed progressively. Here are the data for three regions of the western Atlantic. They do not support the trends indicated by Potsdam’s proxies over the last 150 years.
Such statements require evidence – in this case, not hard to find: the consequences of progressive adjusting, cleaning and homogenising of the original observations that previously had been shown as individually-coloured data plots at NASA Goddard were recently edited on their public website so that it became difficult to visualise any but the final homogenised data. Fortunately for us, they seem to have done the job by hand, and sloppily.
So I was able to find – and recover – their original plots for two stations very relevant to this discussion: Valentia Observatory on the shore of Galway and Vestmannaeyjar on an island south of Iceland. In each, the darker lines of the earlier year of the homogenised data have been shifted very significantly down to introduce significant warming where there was none in the lighter lines representing the unadjusted data. NOAA performs only a very modest adjustment of their GHCN-all data by warming just the final decade to produce their GHCN-M (adjusted) archive.
The pattern of the Galway data, having warmer periods around 1940 and also at the end of the century is repeated at rural stations in Western Europe; it also perfectly reflects the changing value of the NAO and the evolution of the atmospheric pressure field over the northeast Atlantic.
But warnings such as those from Potsdam have had a long history, despite rebuttal: the supposed effects on climate, especially of Europe, of a slowdown of North Atlantic deep convection were discussed in Nature in 2005 just prior to a post-Kyoto climate meeting, in relation to observations of deep flow at lower latitudes. This notion was rapidly challenged by a comment from Carl Wunsch entitled ‘The Atlantic Conveyor may have slowed, but don’t panic yet!’ And it is not surprising that he should have reacted so dogmatically as he did: ‘European readers should be reassured that the Gulf Stream’s existence is a consequence of the large-scale wind system over the North Atlantic Ocean, and of the nature of fluid motion on a rotating planet. The only way to produce an ocean circulation without a Gulf Stream is either to turn off the wind system, or to stop the Earth’s rotation, or both.’
Wunsch might well also have commented that the strongest heat flux from the Gulf Stream to the atmosphere occurs in the western ocean to the south of Nova Scotia, where sun-warmed water from low latitudes encounters very cold polar air. This process is dominated by latent heat of evaporation and is an anomaly of global scale – but along the coasts of western Europe there is little or no heat remaining in he ocean to transfer to the atmosphere.
Consequently, it is clear that the popular image of a broad Gulf Stream sweeping eastwards across the Atlantic Ocean at about 45oN, bearing heat gained in the tropics to maintain Europe’s maritime climate, is unhelpful.
The fact is that everybody seems to have been forgotten that a perfectly good maritime climate exists at similar latitudes on the Pacific coast of North America – where there is no equivalent of the Gulf Stream: in fact, the cold water mass lying along this coast at about the same latitude as Europe, originates in the Gulf of Alaska and brings no warmth with it. But winters are warm and summers cool here, as Richard Seager, an apparently naive English oceanographer, discovered to his surprise when he first visited the US West coast. This maritime climate lacking a Gulf Stream analogue is the consequence of heat carried by south-westerly winds from the distant subtropical gyre across the cold coastal current.
The warmth that these winds bring is not lost to the ocean in passing across the cold Alaskan coastal water, because sensible heat flux between ocean and atmosphere is almost everywhere a loss term. This is due to the micro-structure of the oceanic skin layer across which molecular diffusion dominates; only in high latitude autumn and winter, when strong wind-stress creates breaking waves which disrupt the molecular skin-layer, is there any significant flux of sensible heat from ocean to atmosphere. 
When these ‘anti-trade’ winds pass across the Rocky Mountains, their gyral structure is vertically compressed, expanding horizontally to preserve angular momentum. This forces the storm tracks to curve southwards across the continent so that they encounter the ocean again at a significantly lower latitude – in the northern Caribbean and east of Florida, where sensible heat is transferred to the chilly atmosphere very rapidly. Then, during its north-easterly movement across the Atlantic towards Europe, the surface air mass picks up further heat from the surface of the ocean by sensible heat flux and carries it at a rate that significantly exceeds that carried in the ocean. If these winds crossed the ocean to Europe at the same latitude as they encountered the western Rocky mountains, their consequence for European climate would be much less positive.
These images from Ventusky simulations for (left) air temperature close to the surface on 30 November 2011 and (right) for 31 July 2020. are chosen to show the classical softening of the western European winter climate by warm south-westerly winds (left) and also a very different situation, not often talked about in relation to European climate, concerning our very uncomfortable southern neighbours, North Africa and the Sahara desert.
Such conditions can develop also in winter as they did on 6 February this year when my car, and all the others in town, was speckled with raisin-sized blobs of damp Saharan mud aggregated from dust particles carried in (and fallen from) a low cumulus deck.
So the myth of the maritime, equable climate brought to Europe by the Gulf Stream really needs to be seen for what it is – a myth. It is perhaps appropriate to the British Isles and Scandinavia, but certainly not to the sub-continent as a whole. And, that “Gulf Stream at its lowest in 1000 years” of Potsdam that was trumpeted by a scare-hungry press is perhaps also mythical – but is certainly unhelpful in understanding how the real world actually works.
But I fear that we shall hear more, and probably much more, from the Potsdam Institute for Climate Impact Research as a result of their espousal of a failing Gulf Stream and a chilling Europe – a concept that doesn’t bear close examination: they are, after all, funded to study the fields of “global change, climate impacts, and sustainable development” and I infer from their writings that this is not interpreted as a mandate to try to understand the natural world – and so sometimes, as in this present case, they get it wrong.
Place de l’Eglise
46160 Cajarc, France
 Caesar, L e al.; (2021) . Nature Geoscience, 14, 118-120. 10.1038/s41561-021-00699-z.
 Rahmstorf, S. et al. (2015) Nature Climate Change 5, 475-480, DOI.10.1038NCLIM2554
 Nature (1871) vol. 4, 251-253. Image from Tomczac and Godfrey’s indispensible “Regional Oceanography” of 2002, freely available on-line.
 Kent, E.C. et al. (2013)J. Geophys. Res. 118, 1281-1298.
 Rahmstorf, S. et al. (2015) Nat. Clim. Change 6, DOE. 10.1038/NCLIMATE2554
 from Shearman, R.K. and S.J. Lutz (2010) J. Phys. Oceanogr. 40, 1004-1017
Neto, A.G. et al. (2021) Communications Earth Envir.| https://doi.org/10.1038/s43247-021-00143-
 Bryden, H.L. et al. (2005) Nature, 438, 655-657.
 Wuntsch, C. (2004) Nature, 428, 601.
 Broecker, W.S. (1991) Oceanography 4, 79-89; images, left – Tomczac and Godfrey again and, right, from Bedford Inst. Oceanogr. Rev. 1984.
 Seager, R. et al. (2002) Quart. Roy. J. Meteor. Soc. 128, 2563-2586.
images from Seager, R. (2006) Am. Scient. 94, 334341 and from Tomczak (2003). Annual mean ocean-to-atmosphere heat flux (W.m2)
 Seager, R. et al. (2002) Quat. J. Roy. Met. Soc. 128, 2563 doi.10.1256/qj.01.128
 Cuadros, J. et al. (2015) Atmosph. Envir. 120, 160-172
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Excellently written. Thanks Alan.
Bizzarely, Professor Rahmstorf was an early inspiration of mine, around 15 years ago or so now. He showed a orbital origin for the millennial climate cycle and determined the 1,470-year figure. He tried in vain to fit the data to the tidal influences of the Moon, which happens to have a small peak every 1,800-years.
As I understand it, he was derided by his intellectual peers for chasing the driver of this ‘imaginary climate cycle’. He eventually relented and became the opposite of what he once was: now a champion of the anthropogenic global warming alert campaign.
No doubt the author will be submitting his claims to peer review at a prominent journal where they can be scrutinized by scientific experts. Right?
I tried to offer a comment for publication, but Nature refuses to communicate with persons having no institutional email address. I lost mine when I retired long ago. So, no, I’m afraid you are my peer review, so why dont you comment on the text?
Well, for a start, your title is appropriate, as what follows below that title, is indeed nonsense. You present zero proxy data to refute the proxy data presented in the original publication …
Then you take a dump on the datasets you do present. But somehow that data you take a dump upon appears to support your refutation of said proxy data/paper.
You should get your so-called nonsense published. in a pay-to-play predatory journal. Like this one …
Everett Sarge – I am not sure which side of the proxy argument you are taking in this dispute.
I would say the use of proxies of other proxies which are proxies of other proxies, all with low resolution with respect to what they are trying to measure, would make it difficult to provide any meaningful insight into the relative strength of the gulf stream and / or the north atlantic current over the last 1k years.
If the premise is false the proxies are irrelevant. The AMOC speed does not control Europe’s temperature. Rahmstorf has been a joke for a long time. I read him for laughs.
Nature is funny as well! They in effect claim that the only people who understand science are at universities. This exemplifies the sorry state of climate science today. BTW it is also true for NSF research grants. Only the left wing works, which is why there is only flopping about.
Alan, you aren’t the one making bold claims of an unprecedented change in the jet stream. David’s appeal to authority ignores the obvious fact that you are merely casting doubt on their wild claims. It’s not necessary to disprove claims little green alien creatures are playing croquet in Peoria. It’s up to Stephan and Potsdam to prove that they are.
Well done article.
I did a simple search for information on the Gulf Stream.
First noticed and documented in small part by Ponce de Leon, just around 600 years ago.
First Gulf Stream charting with scientific measurements led by Benjamin Franklin in the 1770s.
First organized scientific study with recorded data by US Coast Survey in 1843.
If I was to pay attention to scientists and data, a millenium-long comparative statement, starting with “never” and concluding with the adjective “weak” has to be at least 60% pure guesswork, but likely closer to 90%.
It is a shame, since this announcement would seem to indicate that anthropogenic global warming will mean cooling in Europe — meaning that it is neither global nor warming, and possibly not even anthropogenic. Should we celebrate?
“But I fear that we shall hear more, and probably much more, from the Potsdam Institute for Climate Impact Research as a result of their espousal of a failing Gulf Stream and a chilling Europe…”
There’s also the contradiction of studies which show the Arctic sea-ice has accelerated melting due to warmer bottom waters from Atlantic intrusion (which has happened in the past on millenial timescales).
The poleward heat transport has decreases by 1.2%. Check “Parametrizarion of energy cycles between the hemispheres”
“So the myth of the maritime, equable climate brought to Europe by the Gulf Stream really needs to be seen for what it is – a myth. It is perhaps appropriate to the British Isles and Scandinavia, but certainly not to the sub-continent as a whole”
Here is a photo of the palm trees in one of the coastal towns in South West England
We have some quite exotic palms susceptible to frosts as well as those that look palmish but are quite hardy. We also have a number of semi tropical gardens. So clearly the Gulf stream does exist and it does have an effect in as much we would expect to be several degrees warmer than inland during the winter but we are likely cooler in the summer.
I would reckon to lose the succulents in my own garden every fourth or fifth winter due to an extended cold spell which is brought in by the direction of the wind. As the author suggests the gulf stream effect is quite limited in its geographic extent and a lot of the extra winter warmth is due to the cloud cover and rain brought in by the prevailing south westerlies rather than the warmth of the water .
Incidentally the relative warmth of coastal Britain was recognised by Tacitus the Roman Historian 2000 years ago
And yet it warms. )
Tacitus also said what a daft idea solar panels were at our latitude. Or at least he commented on our frequent mistiness and cloudiness which is much the same thing
Its pouring with rain at present and the central heating is back on today at 7degrees Centigrade at 10AM Mind you that is only weather of course.
Ah, Tacitus. )
As a “silver surfer” who frequently immerses himself in the North Atlantic I am happy to be able to confirm that the “Gulf Stream” still keeps me warmer than those poor souls on the other side of the pond who indulge in similar nonsensical activities at a similar latitude:
There’s a dilemma here.
My home in Northern Ireland is at the same latitude, 54N, as Prince Rupert Island in British Columbia. The two locations share a similar West coastal location and similar maritime climate.
Yet monthly temperatures average 3C cooler in Prince Rupert Island.
If the North Atlantic circulation is not the cause of the temperature difference , I would be interested to hear your explanation.
The report mentions and I specifically quote it just above, that the British Isles does benefit from it.
Mind you I do think our prevailing winds also have an awful lot to do with our milder winter climate
“Mind you I do think our prevailing winds also have an awful lot to do with our milder winter climate”
This year has emphasised that. Usually NI gets ” warm wet westerly winds in Winter”.
This year we’ve had a lot of Northerlies and Souther!ies. The weather has swung repeatedly between shirtsleeves and snow.
There’s a considerable literature building up on a slowing AMOC.
I think I saw the first paper suggesting reduced sinking off Greenland in 2011.
Is the North Atlantic understood? No! Discussed here: https://1ocean-1climate.com/the-gulf-stream-is-weakening-says-science/ Concerning UK wind, the weather from the East may also play a decisive role. A good example is winter 1939/40, see Fig. https://1ocean-1climate.com/wp-content/uploads/2017/12/3.jpg
As I point out, the West Coast has cold water from Alaska offshore, while Europe has water of the Atlantic Subtropical off its coasts.
Prince Rupert BC averages more than 100 inches of annual precipitation (maybe at least double where you are?) The cooler temperatures could be explained by way more cloud and rain, and consequently a lot fewer hours of sunshine reaches the ground.
More about the Potsdam Institute.
Sorry wrong link in my potsdam comment
Here is the correct link
‘No doubt the author will be submitting his claims to peer review at a prominent journal where they can be scrutinized by scientific experts. Right?’
Well; who is David Appell? And what is the pronunciation of his last name: like ‘apple’ (stress on the first syllable) or French-like Ap´pell, like ‘appeal’, from Anglo-French ‘apeler’, from Old French ‘apeler’, from Latin ‘appelare’ (all verbs), ending up with the English (verb and noun) ‘appeal’. Now, should this explanation be subjected to “peer review”? I have, in my time, had my papers, and other things, subjected to so-called “peer-review” by, on the one hand, some serious experts who were able to furnish me with some diligent comments, and, on the other hand, some fools who had not read half of the words and did not understand the other half. Personally, I have also made expert assessments of papers and research proposals for journals, conferences, and research agencies in a number of countries; and, in these processes also recommended projects that were contrary to my own basic beliefs in my field of expertise. It’s just a matter of integrity and reasoning. But there are also reviewers in the “language sciences” (in a fairly broad sense) who might say that the account above is just “crap” and that the essential thing is the “gender signalling” of Davis Appell’s last name. These “scientists” may not know the difference between the words ‘syllable’ and ‘syllabus’, because that is, in the “language sciences” (in a fairly broad sense), not “relevant”. Neither do they know the difference between UK and US spellings, for instance in ‘scrutinized’ and ‘scrutinised’. So, once again; who is Davis Appell?
Dr Hans Götzsche
Emerito Professore Universitario
Via S. Apollinare 19,2
36063 Marostica (VI)
“Who is David Appell?”
That seems to be a common question around these parts.
Clearly a sufficient threat to the denialist worldview that they feel the need to ridicule him.
No threat. If he elevated his discourse beyond 5th grade equations and actually knew the science as he purports to know, he might be a threat. Greta is not being dismissed because she is a threat. She is being dismissed because she egregiously oversimplifies the debate.
Longhurst is not the Lone Ranger. This paper finds no declining AMOC. There is a debate about the issue in the scientific community.
I hadn’t realised that an ability to solve the Navier-Stokes equations was a necessary qualification for posting comments here.
That disqualifies almost everybody.
I believe this question is best answered by Mr. Appell himself:
No Appell biography is needed. Everything one needs to know about him is included in that one thread.
New phone. Who dis?
At least the second time Hans hides his true qualifications.
This paper mentions the very large uncertainty about the future of the AMOC. It doesn’t say uncertainty. It doesn’t even say large uncertainty. It says very large uncertainty.
Acknowledging uncertainty by the scientists is not unusual. It is to be expected. In a very complex field such as climate science that is the way it should be. But how much of the uncertainty is conveyed in the popular press?
The press is not there to do anything as pedestrian as reporting the facts. They are on a mission to save the world. Kudos to all the scientists who try to find the truth about the science. No kudos to ideologically driven media.
I know that the overturning slows down, but looking at the RAPID data, the low MOC events, which are typically during negative North Atlantic Oscillation episodes, see a very slight speeding up of the Gulf Stream. Maybe because there is less resistance in the Gulf Stream spilling into the Arctic than by overturning at the Achilles heel of the North Atlantic.
The increase in negative NAO conditions during centennial solar minima, does appear to see more warm flow transported into the far North Atlantic and Arctic.
Interestingly in relation to the longer chart series in the post, and with this chart, is the very cold CET period 1836-1845, which was almost as cold as the coldest CET part of the Dalton minimum 1807-1817.
On second thoughts there’s a problem with that, it’s colder with more ice then.
Forgot to add the link – https://www.nature.com/articles/s41561-021-00699-z
The study compares three long term proxies each with error bars and a comparison – despite the shortcomings of individual proxies – provides a robust picture of AMOC evolution. These extend into the 20th century when temperature based proxies are possible. In the 21st century there is the 26 degrees north array.
‘a, The SST-based proxies (light and dark blue) represent the North Atlantic temperature response to changes in the Atlantic meridional heat transport associated with an AMOC slowdown. b–k, It is compared with proxy records of subsurface ocean temperatures (purple) (b), δ15N data of deep-sea gorgonian corals (magenta) (c,h), mean grain size of sortable-silt data ss¯¯¯¯¯ (shades of green, shown with a 12-year lag to the temperature-based indices3) (d,i), δ18O data in benthic foraminifera (shades of brown) (e,j), the relative abundance of T. quinqueloba in marine sediment cores (orange-red) (f), methanesulfonic acid concentration in Greenland ice cores (orange) (f,k), both indicators for local/regional marine productivity, and the relative change in Atlantic Ocean heat content versus that in the Southern Ocean (dark magenta) (g). As a reference for the actual change in volume transport, the April 2004–April 2018 linear trend of the RAPID data4 (black) is given (g). The map (using the same colour-coding as the time series) gives an overview of the various locations the proxies were taken from (with small markers denoting single sites and large markers denoting the areas with multiple proxy sites). All curves were smoothed with a 20-year (50-year) LOWESS filter for the shorter (longer) time series to make them more comparable. Shading and error bars show the 2σ (95%) confidence intervals of the individual proxies as they were reported and the uncertainty of the AMOC representation of the Caesar et al. (2018) temperature proxy, respectively (Methods). SPG, subpolar gyre; VPDB, Vienna PeeDee Belemnite; ZJ, zetajoules.’
I am far too skeptical to read much of this post. The warning signs and the lack of rigour are all too apparent.
I’m sorry that you didnt read the rest, because then you’d have understood the main point of the post – that the heat transported in the ocean to Europe is not what gives Europe its maritime climate but rather it is transport in the atmosphere as Richard Seager has demonstrated in a series of papers; if you are interested, I’ll post a bibliograohy of the topic. So, for this issue, which was what Potsdam ensured should hit the Press, the proxies are largely irelevant.
Changing your premise? I suggest you retract and rewrite.
One small correction, Valentia is in Southwest Ireland, Co. Kerry.
(Galway is 150km north along the West coast)
Second Note, Another paper from Worthington et al published around the same time as Cesar et al that relied on observations to build a higher resolution model, found that over last 30 years no weakening of AMOC. Interestingly this paper got no publicity!. Second Interesting thing is that one researcher – G McCarthy was contributor to both papers!
The data from the 26 degree north array is unambiguous – they then tune a model to it. Models are suddenly sacred writ? Beyond nonsense.
Nice reverse trolling re climate models, lol…
Two of the authors are members of the RAPID MOC research team (https://rapid.ac.uk/rapidmoc/people.php)…
Oh and in case you did not get the memo, here is more recent nonsense from them where annoying measurements suggest a pending recovery in the AMOC.
Going straight to the memo’s conclusive conclusions.
‘However, the lead–lag relationships between the AMOC at two latitudes (26 and 45◦ N) cannot be conclusively determined. Additionally, the AMOC at 26◦ N does not yet appear to be responding to the intense buoyancy loss in the subpolar gyre in 2013–2015. Based on the findings in Desbruyères et al. (2019) that the AMOC at 45◦ N lags basin-wide surface forced transformation in the subpolar gyre by 5 years, and
the tentative 0- to 2-year lag from the AMOC at 45◦ N to the AMOC at 26◦ N, we would anticipate an intensification
in the overturning strength at 26◦ N in response to the 2013–2015 forcing by 2018–2022 and may become apparent in the next recovery of the RAPID observations.’ https://os.copernicus.org/articles/16/863/2020/
I’ll had a quick look, Needs further thought. I am rather confused about how a decline in AMOC strength connotes a pending recovery. Something to do with winds and the state of the north Atlantic. From Smeed et al 2014.
And Smeed et al 2018 for good measure.
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Oh, i just saw “Entropic Man” saying about David Appell that “Clearly a sufficient threat to the denialist worldview that they feel the need to ridicule him.” Then I wonder, what is a “denialist”? My Mac dictionary says that “a person who refuses to admit the truth of a concept or proposition that is supported by the majority of scientific or historical evidence: the small minority of very vocal climate change denialists | [as modifier] : the denialist view.” So even lexicographers can be confused, or deluded. The Currie blog is, so to speak, evidence that there is no conclusive evidence “supported by the majority of scientific [whatever]”. And the notion of truth has been contemplated by philosophers for more than 2.500 years and it is not an easy concept, so the lexicographer jumps to conclusion. Apart from that the misnomer “climate change denialist”, is beautifully abbreviated by non-denialists from the original ‘ANTROPOGENIC climate change denialist’. I feel no urge to ridicule “Entropic man” but I might ask what thermodynamics has to do with him personally? Have a nice weekend.
Quit playing dumb, Hans. There’s a whole range of things contrarians deny:
And indeed you’re trying to ridicule EM with your apophasis. Since you like wordology:
“The device is also called paralipsis (παράλειψις) – also spelled paraleipsis or paralepsis – or occupatio, and known also as praeteritio, preterition, or parasiopesis.”
Mostly they deny that Climateball, willard’s sole contribution to the climate conversation, has anything to do with the reality of people searching to understand the extent and implications of human contributions to climate change.
Turning it all into a game to allow you to make fun of your opponents has not only limited utility, it had a limited lifespan for everyone but yourself.
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Even though ‘the word sciences’ are my business’ I don’t know the word “wordology”, but, of course new words pop up all the time. Neither have I heard the phrase “don’t play dumb” but it must be an idiomatic expression in some dialect. What we know we know by means of the words we use about things, and the words we use about each other are often not based on what we know. On this blog some of you play the word game and others take part in the data wars. In order to find out how things work in the big context I prefer the last kind of activity, but the exchanges are often disturbed by word games. As for “paralipsis” you might observe that not everyting on some Wiki-page is correct. All the best. HansG
You have yet to enter in one of what you call “data wars,” Hans, and there’s a big difference between saying that something might be untrue and showing that it is. As for playing dumb:
You might wish to search for the expression “going emeritus” too.
Lastly, be aware that you can reply directly to the comments to which you reply. Just click on “reply” right above the comment. Like I just did.
Thanks for the information. So I’ll do. I don’t interfere much in the ‘data wars’ because not much of it is my field of expertise. I read the blog because I would like to know more about the things I don’t know so much about; among other things the Longhurst article above. Therefore I prefer less word games. As for truth it’s not easy to “show that something might be untrue”. Only contingent truths can be falsified; the others truths are based on inferences and other kinds of reasoning so it’s more complicated. I can’t find “go emeritus” but I guess it’s a kind of invective.
The proposal was not “go emeritus”, but “going emeritus”. Actually, it is a polite term: https://www.reddit.com/r/skeptic/comments/2ewtub/til_when_an_older_scientist_loses_touch_with/
It possible to say that Hans has gone emeritus, George. Ask Hans about how verbs work.
It’s very easy to prove that some contingent statement might be untrue, Hans. For instance, there would be no need to rely on fuzzy description logic to show how thy Wiki is incorrect in how it describes your passive aggressive irony.
The AMOC has enemies on all sides.
The warmists don’t like it because it provides a non-CO2 explanation for climate change.
The sun worshipers don’t like it either for the same reason – it provides a non-solar explanation for climate change.
But denying the AMOC – and denying oceanography in general – is futile. The ocean is real. Ignoring it won’t make it go away.
And it’s not only the – admittedly alarmist – Potsdam institute who hold to the controversial view that the earth has a billion odd km cubed of water around it. And not only Potsdam believe in the AMOC. A much more significant paper on the AMOC was published this year by a French group, matching climatic changes over the last 50,000 years with changes in the AMOC measures by ocean floor profiles of sediment grain size. They confirm that periods of faster AMOC are warmer (in the NH at least) due to more poleward ocean heat transfer, and conversely slower AMOC circulation results in colder periods.
This will annoy the carbonara warmists who up to now have argued that both speeding up and slowing down of the AMOC – both cause warming! Sorry but you can’t have your cake 🎂 and eat it.
“French group, matching climatic changes over the last 50,000 years with changes in the AMOC measures by ocean floor profiles of sediment grain size. They confirm that periods of faster AMOC are warmer (in the NH at least) due to more poleward ocean heat transfer, and conversely slower AMOC circulation results in colder periods.” – Phil
That fits the increase in tidal energy due to new physics gravitational forcing. More tidal energy at the equator implies stronger ocean currents.
On a glacial timescale, the extra ocean energy poleward would also increase precipitation which falls as snow, which accumulates.
The oscillation of the AMOC between stronger and weaker phases arises from the North Atlantic being an excitable medium, driven by the salinity-downwelling positive feedback in the region of the Norwegian Sea. Here are some thoughts along these lines –
There’s the same amount of evidence for this hypothesis as there is for new physics gravitational forcing.
And the evidence for a “new physics gravitational forcing” is what?
“And the evidence for a “new physics gravitational forcing” is what?” – Appell
It’s a logical possibility and should be recognised as so by the science community. The hypothesis predicts that the solid body earth-tides of the equator are steadily increasing. A careful satellite study could test for this, with the equatorial bulge of the lithosphere rising up by around 1m.
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Alan mentions that “the North Atlantic Current… eventually enters the Arctic Ocean” but his infographic doesn’t extend far enough north to show the West Spitsbergen Current.
Over the last few weeks lots of by now ex Arctic sea ice has been driven to destruction in its “warm and salty Atlantic Water”. See for example:
Allow me to summarise my experience after entering the debate on “North Atlantic Nonsense”. If you’re not interested you can skip this. I don’t think Judith Currie is interested; I guess she knows how it works. But I shall try to make it short.
Many comments are balanced and reasonable but I noticed some comments by Davis Appell, one of them referring to “peer riview”. It is well known that much peer review of today doesn’t work, among other things because papers may have more than 25 co-authors and because experts on one’s tiny sub-topic may be hard to find outside the group of co-authors. So what was the point of saying so? I therefore left a comment and made my identity explicit. I admit that my comment was ironical, dealing with the last name “Appell”, to illustrate the void reference to “peer review”, and it was explicating my personal experience with the peer review system. I also asked for David Appell’s background for his – as perceived by me – unpleasant comments.
One comment (“Entropic man”) instantly fused personal matters with the subject of the debate in the word “denialist”, and then the scene was set for person-bashing. Willard found my INTEL connection and my academic affiliation, followed by Appell’s remark: “Hans … is a weak man and not a man of science”. So David (all Americans seem to be at first-name terms with all other American) knows me better than my wife’s dog; a very nice cairn terrier, originally from Skye. Some metaphysics must have been invoked here. Also Willard knows me better than my wife because he can say: “don’t play dumb, Hans”, and refers to the ‘contrarians matrix’. This “matrix” looks as if amateur phychology has taken over the debate on a scientific subject. And Willard refers to a Wiki-page explaining the word “paralipsis”, and introduces the word “wordology”. This is, actually, my field of expertise and Wiki-pages are not always accurate. It is also a field (terminology/nomenclature) in which I can contribute to the theme of “climate”. On
the word history of ‘climate’ is accounted for, and it should, only, mean ‘the weather over a long period of time in a certain place on the surface of earth. By semantic confusion it has ended up as also meaning “global climate”, which is, in the outset, a contradiction in terms. Does it matter? I don’t know. I’ll presumably be dead when somebody remembers the historical past of certain words.
Another thing that I can say something about is ‘theoretical approaches’. Language use, economical dynamics, the spread of a virus, and the atmosphere are all complex dynamical systems. Maybe the atmosphere is a hyper-complex system but there are parallels in the approaches that can be made to the different systems; and this should be acknowledged. My basic attitude on the theme of so-called global warming is the question of uncertainties in chaotic systems. There is a reach literature on this but answers are not yet definitive.
And just a few words on science. The word has been used by so many and in so many contexts that it is, today, almost vacuous. But there is no such thing as ‘science as such’. There are scientist who, mostly, try to do a decent job. And a scientist can be defined as a person who is employed (or has been and is now emeritus) by a research institution, often a university, that is expected to produce, store and disseminate reliable knowledge. The core word is here: reliability. I agree with the biologist Richard Dawkins that ‘scientific truth is under threat’ (I can’t find the link) but I wouldn’t use the word ‘truth’. I prefer the term ‘reliable and justifiable knowledge’. And this is what Longhurst’s article above lives up to; so it can be the topic of a qualified debate. If the – should we call them – ‘externalities’ of the debate have to follow, then also I will have to live with that.
But not everything in this line of comments is qualified and it’s hard to be a newcomer as a commenter. In the company of hard-bloggers I’m just an amateur. I have no personal experience with so-called social media; you won’t find me on facebook or twitter; but I taught linguistics and communication on Communication Studies for more than ten years and I’ve supervised quite a lot of student projects on social media, so I’ve heard sufficiently about the public guillotine in action. But, anyhow, I was surprised by the patronising expressed by hard-line bloggers here.
I suppose it’s a matter of a cross-Atlantic culture clash. Europeans, mainly in Scandinavia, watch so many American movies that they think they know American culture; which they don’t. One of my grandchildren is 50% American so I know how little I know about American culture. But, anyhow, I was surprised when entering this blog. Also by the blog’s untold rules and the implicit hierachy, and the group-talk, mainly expressed in collocations or idioms that are expected to be known by the bloggers.
I assume that, if anybody will reply to this, there will be personal attacks on me. But having survived an academic, scientific career makes me – if not immune then – less vulnerable. So I’ll survive.
I’m still impressed by Longhurst’s article.
All the best to everybody,
Thank you for your thoughtful post.
I’m not a scientist. Just one of the many people, all of us actually, who support science by working, producing wealth in society and … paying taxes. I’m here to see how my money is being spent. And, to learn as much as I’m able from those who have much to offer.
I’ve never met Judith Curry, but I think she actually does care, very much. 1) She provides this forum, 2) She stays out of the fray and doesn’t exert undue influence in the discussions, which is smart, and 3) Unlike most people on this blog, she actually has a job that is productive, as she owns and runs a going concern, which from my personal experience must have enormous demands on her time. Yet, she posts a prodigious amount of material for us.
If you stick around, I think you’ll find many interesting people here. Oh yes, there are those who like to hurl insults. Conversation bullies, angry nerds with words, who most probably have never had an actual physical confrontation. Ah, the life of the privileged neurotic! No matter, as in every endeavor one must separate the wheat from the chaff. And truth be told, some of the worst offenders have contributed some very interesting information. Isn’t that what we’re here for?
As for Americans, well what can I say … we can be a disrespectful bunch. Emotional, competitive, always obsessed with time and tend to take shortcuts. Our Holy Grail is ‘the answer’, which we either know and will inform you directly (whether you like it or not) (check that, mostly if you don’t like it), or we expect is just about to be discovered … by us, of course. Yet, there are some redeeming qualities …
One thing is certain, at Climate Etc there is open debate.
Enjoy, your day!
(sorry, but I still prefer old-fashioned honorifics like ‘dear’)
thanks for your kind words. And be sure:
I fully agre on Judith Currie. That’s why I use this website as my primary source of updated information on a number of scientific topics.
And I also respect people like you, just working and creating wealth for other people. But sometimes I think that you’re, somehow, exploited by academics like me. I started my teen-life going to school and working on my farther’s farm in the afternoon and in the evening, After that I was in the army, passed a teacher’s exam and was a secondary school teacher for 15 years while studying at university in the late hours. So my respect is not just a symbolic attitude; I’ve experienced real life, ie. the soil of farmland, and I know how life is for hard-working people.
I (personally) know a number of Americans whom I highly respect. Noam Chomsky, as a linguist and a decent human being – even though I disagree with his so-called ‘generative approach’ in linguistics – and other people in the US. I won’t try to pretend that Denmark, Sweden, Finland, Germany and Italy are ideal cultures; because they are not, and they lack some of the urge to personal freedom that I see in the US.
So, I’ll stick around; and maybe your words can make me offer some input on matters that I know something about. And get to know interesting people.
Hans Götzsche | May 15, 2021 at 11:35 am says (part quote) “I’ve experienced real life, ie. the soil of farmland, and I know how life is for hard-working people.”
I could not resist adding my 2c worth. “the soil of farmland”, that, as I am finding late in life, is one of the best teachers in many aspects (I share that experience). In the immediate sense it means hard work, but looking back across the centuries it also means survival and the striving to avert the First horseman – Famine-.
I do not know about Hans’ soil, but mine has been farmed for long millennia. Only relatively recently have I begun to understand the soil. How it was protected against times of flood, and how it was augmented to provide a livelihood in times of drought. Civlisations rose and collapsed because of their soil. I’m beginning to realise the(my) soil’s history, the geological upheavals that destroyed and remade it, in relatively recent times (post end of YD, and contrary to established beliefs). In contrast to today, where soil=dirt, to succumb to asphalt and concrete.
That same soil tells of the people that farmed it. Man always in the past respected the soil and returned to it all that was taken from it. The tell tales are all there, a reminder from time to time. And indelible across the millennia are his own ‘footsteps’.
We live in a ‘glitch’ of time. Millennia of agrarian practice that did not change much (except for the long biological development of strains of food types – the cereals- that may also be in danger of being lost), but in a matter of a century has been mechanised to an unbelievable degree. That scientific development can also be lost in a ‘wink’, and that would not be the first time, as I have recently found out.
How a professional modeler would address Climate Change. A “Stepwise” approach to building a robust, serious, professional Climate Model. If you are building a pregnancy test model, you don’t include men, pre-pubescent children, post-menopause women, sterile, and other populations because they make the results nonsensical. The data sets chosen have to be relevant to the questions being asked. Imagine how idiotic the results would be if we included men in pregnancy tests? That is what an aggregate climate model is. AN idiotic construction of dissimilar data sets all put in a blender. Their results are nonsensical and effectively meaningless.
How then would a professional modeler create a climate model?
1) Start with a data set that has as many exogenous and/or variables as possible.
2) Antarctica and cold and dry deserts are ideal for controlling for the Urban Heat Island Effect and Water Vapor. The only real variables are CO2, Clouds, air currents and Sun.
3) Run a regression of temperatures and CO2 using the data from Antarctica or a composite of desert locations. https://imgur.com/a/mHIjixS#BLncbpV
4) The Error you get is due to Clouds, Sun, and air currents, and the coefficient on CO2 is the relationship and CO2 and Temperature. Most likely, you will get a 0.00 on CO2, even when CO2 increases by 25%.
5) Take the error of the regression, and use that at the data for normal variation or temperature due to exogenous factors.
6) The next model would use the data set right above Antarctica. That data set is close to Antarctica, but has more exposure to the oceans.
7) Run a regression using the Antarctica Error, CO2, and Temperature. The error you get from this model is the variability due to adding the effect of oceans to the data set.
8) The next model uses the data set next higher up on the latitude that would include Land.
9) Run a regression using CO2, the Antarctica Error, the Ocean surrounding Antarctica error against temperature. The error you get is due the impact of adding land. (Yes, I know if isn’t perfect, but it is infinitely better than the nonsense being created today) The current models are a joke.
By using a stepwise approach of using similar data sets, and using the error to explain the exogenous variable, and using that exogenous variable as an indigenous variable in the new model, climate modelers would be able to slowly build more accurate climate models. Because each region of the globe has different indigenous variables, an aggregate model is a 100% complete joke.
Climate models should be done by regions to isolate the impact of the known indigenous variables on temperature.
Publishing trends on data sets that don’t have linear trends is pure nonsense. ANOVA Table statistics should be published. That would give you model R^2, variable coefficients, and the significance of those variables. That is how a professional model is built. Show me any real field of science that doesn’t produce ANOVA Tables? Linear trends are nonsensical when applied to temperatures. They literally tell you nothing about what is causing the warming.
I agree with you overall but that figure that’s been circulating a lot recently is not quite representative. Apparently it takes one of the highest temperature model runs and repeats many iterations of that model – to make it look like all the models are running very high. They are – but not quite by that much.
Thanks Phil. I guess my main point is that to prove CO2 causes warming you have to use data sets that isolate the impact of CO2 on temperatures, Antarctica is the best data set and it clearly shows no warming even with a 25% increase in CO2. The data sets are warming due to something other than CO2.
Antarctica is certainly the best data set. Thats why I sued it in my recent post on polar climates. But, the South Pole set you chose is not the best. Ity has a site change problem. Using only BAS-approved data for the continental stations and AWS data from above Scott Bay, there is neglibible progressive warming during the observational period.
I suggested in my text that this supported a very low value for CO2 sensitivity – but nobody noticed the suugestion…tyey got to arguing about other matters.
Start with a data set that has as many exogenous and/or variables as possible.
Start with a data set that has as few exogenous and/or variables as possible.
In researching the AMOC I found a paper Wanamaker 2012, which said the AMOC strengthened in 1940. This triggered a memory that studies said the dynamics of warm waters affecting Pine Island Glacier thinning began in the 1940s. Smith 2017, Steig 2017, Rignot 2017. Schneider 2008 pointed out the 1939-42 El Nino affected the warm waters off PIG.
Consequently, it is clear that the popular image of a broad Gulf Stream sweeping eastwards across the Atlantic Ocean at about 45oN, bearing heat gained in the tropics to maintain Europe’s maritime climate, is unhelpful.
The fact is that everybody seems to have been forgotten that a perfectly good maritime climate exists at similar latitudes on the Pacific coast of North America
This is a big geography fail.
Take the U.K. – this is not equivalent in latitude to the USA. Not to San Francisco or even Vancouver but quite a lot further north. Britain’s latitude extent between 50 and 60 north makes it level with much colder (in winter) coastal British Columbia on the west side and northeastern Quebec on the east coast. It’s even level with the southern tip of Hudson Bay. Moving to the east Eurasian coast, we’re talking about the Kamchatka peninsula and very cold Siberian latitudes. The Shetlands are even on a latitude with Magadan. All these places, while also coastal, are quite a lot colder than Britain in winter. The traditional attribution of this to the “Gulf Stream” is correct.
The Gulf Stream and AMOC are a consequence of the current continental layout of the earth, in particular the unusual presence of a meridionally bounded ocean – the Atlantic. Bounded by land to the east and west almost from pole to pole. This forces ocean currents into a lot of north-south movement. This cases the AMOC and the related phenomenon of heat piracy across the equator stealing heat from SH to NH.
“This cases the AMOC and the related phenomenon of heat piracy across the equator stealing heat from SH to NH.” – Phil
Sounds like BS.
Heat piracy is for real.
What’s even better is that it happens in the vicinity of the Caribbean 😂
Phil Salmon: This cases the AMOC and the related phenomenon of heat piracy across the equator stealing heat from SH to NH.
How droll: “piracy” to denote physical processes without human interventions.
I did not invent the term “heat piracy”
Phil: so you believe in millennial scale climate cycles then?
“The millennial‐scale asynchrony of Antarctic and Greenland climate records during the last glacial period implies that the global climate system acts as a bipolar see‐saw driven by either high‐latitudinal and/or near‐equatorial sea‐surface perturbations.”
New physics gravitational forcing has an alternative to ‘heat piracy’. The orbital forcing would change from a north-south orientation to a south-north orientation with changing orbital inclination. The forcing body would be above the solar plane on one cycle and below the solar plane on the next cycle.
The explanation for the current Northern hemisphere warming being 3x faster than the Southern hemisphere would be due to the unknown body moving from below the solar plane to above it.
I propose that this millennial cycle is due to a ‘dark moon’ of Jupiter which is responsible for the Trojan asteroids which orbit infront of and behind the Jovian planet.
Sabine Hossenfelder’s take is that the new data discrepancies leave it as 50-50 as to whether new physics is needed or whether dark matter can be stretched to fill the holes. New physics would be cooler of course…
‘Quantum mechanics has irked physicists ever since its conception more than 100 years ago. While some of the misgivings, such as it being unintuitive, are merely aesthetic, quantum mechanics has one serious shortcoming: it lacks a physical description of the measurement process. This “measurement problem” indicates that quantum mechanics is at least an incomplete theory—good as far as it goes, but missing a piece—or, more radically, is in need of complete overhaul. Here we describe an approach which may provide this sought-for completion or replacement: Superdeterminism… Superdeterminism is a promising approach not only to solve the measurement problem, but also to understand the apparent non-locality of quantum physics. Most importantly, we will discuss how it may be possible to test this hypothesis in an (almost) model independent way.’ https://www.frontiersin.org/articles/10.3389/fphy.2020.00139/full
New physics is a superdeterministic theory of quantum mechanics and the entropic theory of gravity. Not some oddball notion of a neutron star whizzing around the solar system.
The Southern hemisphere is experiencing a cold snap this year, just like we’re experiencing here:
NEW ZEALAND SWINGS FROM RECORD HEAT TO RECORD COLD + NEW STUDY SHOWS ANTARCTIC SEA ICE IS GROWING
So you have given up your ‘new physics’ nonsense and have taken up weather forecasting instead.
‘However, there is evidence that the onset of the Heinrich Stadial 1 AMOC slowdown started ~18.5 ka (Ng et al., 2018; Stern & Lisiecki, 2013), much earlier than Heinrich Event 1 (Hall et al., 2006; Hodell et al., 2017; Stern & Lisiecki, 2013). This chain of events, whereby the onset of the Heinrich Stadial (a multimillennial period of low Northern Hemisphere temperatures, which may be linked to a relatively weak or collapsed AMOC) preceded the Heinrich Event (a shorter period of enhanced iceberg calving, captured by sedimentary ice rafted debris records in the North Atlantic), is consistent with earlier time periods (Barker et al., 2015; Bond & Lotti, 1995); note the distinction between Heinrich Stadials and Heinrich Events. Furthermore, climate models suggest that Heinrich Stadial‐like conditions can only be simulated during or close after glacial climates if unrealistically large iceberg‐derived freshwater fluxes are adopted (e.g., compared to estimates by Roberts et al., 2014). What, then, could have forced the AMOC slowdown and northern cooling that began ~18.5 ka?’ https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2017PA003308
The key to much cooler NH temps seems to be high northern latitude ice sheet feedback. But could it possibly start with borealization of the Arctic Ocean?
Quote part from above: “Heinrich Event (a shorter period of enhanced iceberg calving, captured by sedimentary ice rafted debris records in the North Atlantic)”.
On North Atlantic ice rafting debris see fig4 in link here https://scholarworks.wm.edu/cgi/viewcontent.cgi?article=2034&context=aspubs
In fig4 B note the abrupt change at 7k2 (5200bce) and 5k2BP (3200bce)
In fig4 C -and D- note the spikes at 6200bce; 4375bce 2345bce.
All are Eddy cycle roots; in sequence. 3550bce spike is also an abrupt event, but now at near mid-cycle peak.
Evidence of a regular driver.
Evidence of irregular internal mechanisms.
I agree that it’s ice sheet feedback that is key. I guess there are several systems with feedback relating to Arctic ice, one of them being the salinity-downwelling feedback that drives the AMOC.
“Borealization” – my new word for today 😁.
Gee – I wondered why it was called thermohaline circulation.
Tropical water carried toward Europe on the Gulf Stream ocean is more saline than North Atlantic water. But eventually this water – still having higher makes its way to the region between Norway and Greenland where it gets cooled down. This combination of near freezing temperature and still higher salinity gives this water very high density – enough to make it sink right down to the ocean floor. This downwelling is the “propeller” that drives the global system of 3-dimensional ocean circulation that is – as you say – for that reason called the “Thermohaline circulation” or THC. The downwelling such as in the Norwegian Sea is also called “deep water formation”.
The reason why it’s a positive feedback is that the downwelled cold water flows south along the ocean floor. (It’s not uncommon in the THC for currents at different depths to be flowing in different directions.) For conservation of mass and to prevent an embarrassing slope developing on the ocean surface, water at the surface has to flow north to compensate; in this way the flow circuit of the Gulf Stream – called the AMOC or Atlantic Meridional Overturning Circulation, self-reinforces in a positive feedback.
This positive feedback is intermittent and not continuous – otherwise the North Atlantic would end up spinning like a washing machine or the scene at the end of Pirates of the Caribbean – at world’s end. Accelerated Gulf Stream circulation warms the Arctic by carrying warm water northward. However this warmth melts Arctic ice eventually releasing into the North Atlantic enough fresh water to choke off the Norwegian Sea downwelling. Then we’re back to square one and the cycle begins again. It’s chaotically intermittent with a time period varying between 30-70 years, and is sometimes called the AMO (Atlantic Multidecadal Oscillation).
The wind-driven Atlantic South Equatorial Current seems to bifurcate where is comes up against the eastern tip of South America – in the region of Recife, Brazil. This (apparently) results in trans-equatorial transport of a large amount of warm southern hemisphere water into the northern hemisphere (u.e. SH to NH). To maintain mass balance there must be another mode of trans-equatorial transport running from NH to SH. Credible oceanographers (Wunsch, Munk, Stommel) indicate that the mass-balance is maintained by southwards movement of the Atlantic Deepwater. So according to this theory, more Equatorial Atlantic heat gets directed into the North Atlantic.
That having been said, I do think that Broeker’s “Global Fan Belt” is a gross oversimplification and complete nonsense.
I think that might be conveyer belt – not fan belt. There are a number of processes – Coriolis force, the northern annular mode, stratification, ice formation and melting, boundary conditions – leading to ‘borealization’ – changes in complex horizontal and vertical water profiles in the Arctic Ocean that I am far from understanding. That Igor Polyakov suggests looks like a change in the state of the Arctic.
I was being sarcastic when I substituted ‘fan belt’ for ‘conveyor belt’. The idea that all the world’s currents could stop or slow-down due to a slowing of the Gulf-Stream has got to be nonsense. The surface currents are overwhelmingly wind-driven – with the Tradewinds being the key drivers. The Tradewinds are driven by the tremendously powerful Hadley Cell. The Hadley Cell – being bottom-heated (NB “heated”) makes for a vast and efficient Heat Engine. Thermohaline negative buoyancy on the other hand, is a heat-engine with miniscule driving power – being top-cooled. One could try to make a heat-engine that ran on dry-ice. But it wouldn’t get very far.
The Earth’s currents are a hugely complex, highly redundant system of multiple banks of heat engines or drivers. If one cockamamie little driver called the Thermohaline effect were to fail, the whole system would hardly notice.
Reblogged this on Climate Collections.
“Over the last 12,000 years virtually every centennial time-scale increase in drift ice documented in our North Atlantic records was tied to a solar minimum. ~Henrik Svensmark
Thank you Alan Longhurst
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If one is to form ideas about models and concepts, one has to start with available data. One of the foirst steps is to determine how much trust should be placed in the historic data. In terms of temperatures,there has been much talk about homogenisation and missing data and interpolation, but it seems that the land temperatures might have a problem not yet dealt with well enough.
As my colleage Bill Johnston has noted shown repeatedly on his blog named bomwatch, using Australian adata as an example, the solid evidence indicates that rainfall affects the temperatures observed in your typical Stevenson screen. There are valid physics behind this. Rainfall cools.
Analogy. The surveyor used to use a metal tape to measure distance between 2 places. The tape was known to expand when in hot air compared to cold air. The thermal coefficient of expansion was measured, so a correction was applied to distances affected by temperature. Surveyors who did not do this found they could not close a survey, plus their measurements could not be reproduced except by coincidence of variables, plus they risked betterr surveyors taking the badges off colleagues who failed to correct distance for temperature.
Here is a graph that relates the effect of annual rainfall and annual maximum temperatures for 24 sites around Australia. The units on the X axis are the annual Tmax temperature trend change in degrees C per meter of rainfall per year. The Y-axis shows how far the weather station was from the coastline of Australia, with + values being offshore islands and – values being far inland.
Obviously, the effects of rainfall at this annual scale are a mix of explainable properties and others yet to be explained well. There is a clear inference that the effect of rainfall on Tmax varies over an order of magnitude mathematically, so it is worth seeking a correction.
Just as surveyors correct for T on metal tapes.
Until this is done for T at your customary station, you have to wonder which version of T should be used in models using physics, Is the usual reported value valid, or should one correct for rainfall?
Over to you. Geoff S
‘H = Cp T + L q
where Cp is the specific heat of air at constant pressure, T is the air temperature, L is the latent
heat of vaporization, and q is the specific humidity [Haltiner and Williams, 1980].The quantity, H, is called moist static energy and can be expressed in units of Joules/kg.’ https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2004EO210004
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The water stripped off early is the warmest water. Sustainable throughput is needed.
You can’t stop these circulations.