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New studies confirm weakening of the Gulf Stream circulation (AMOC)

Filed under: — stefan @ 17 September 2020

Many of the earlier predictions of climate research have now become reality. The world is getting warmer, sea levels are rising faster and faster, and more frequent heat waves, extreme rainfall, devastating wildfires and more severe tropical storms are affecting many millions of people. Now there is growing evidence that another climate forecast is already coming true: the Gulf Stream system in the Atlantic is apparently weakening, with consequences for Europe too.

The gigantic overturning circulation of the Atlantic water (dubbed AMOC) moves almost 20 million cubic meters of water per second – almost a hundred times the Amazon flow. Warm surface water flows to the north and returns to the south as a cold deep current. This means an enormous heat transport – more than a million gigawatts, almost one hundred times the energy consumption of mankind. This heat is released into the air in the northern Atlantic and has a lasting effect on our climate.

But since the 1980s, climate researchers have been warning of a weakening or even a cessation of this flow as a result of global warming. In 1987, the famous US oceanographer Wally Broecker titled an article in the scientific journal Nature “Unpleasant surprises in the greenhouse”. Even Hollywood took up the subject in 2004 in the film “The Day After Tomorrow” by the German director Roland Emmerich. However, there were no measurement data that could prove an ongoing slowdown.

Only since 2004 has there been continuous monitoring at 26°N in the Atlantic (RAPID project). Although the data show a weakening of the current system, the measurement series is still too short to distinguish a possible climate trend from decadal variability. For the longer-term development of the Gulf Stream system, we must therefore rely on indirect evidence.

A long-term AMOC weakening should lead to a cooling in the northern Atlantic. Such a regional cooling in the middle of global warming has been predicted by climate models for a long time. And indeed, the evaluation of data on sea surface temperatures shows that the northern Atlantic is the only region of the world that has escaped global warming and has even cooled down since the 19th century (see graph). In addition, one can see a particularly strong warming off the North American coast, which according to model simulations is part of the characteristic “fingerprint” of a weakening of the Gulf Stream circulation.

Diagram of the Gulf Stream system with the warm surface current and the cold deep current. The actual Gulf Stream off the US coast is a part of this more comprehensive circulation system. The color shading shows the measured temperature trend since the late 19th century. This diagram is based on Caesar et al., Nature 2018 and first appeared in the Washington Post.

This fingerprint is regarded as important evidence, and not least because of this, the Intergovernmental Panel on Climate Change (IPCC) stated for the first time a year ago in the Summary for Policy Makers of its Special Report on the Oceans:

 “Observations, both in situ (2004–2017) and based on sea surface temperature reconstructions, indicate that the Atlantic Meridional Overturning Circulation (AMOC) has weakened relative to 1850–1900.”

New studies support long-term weakening

Two new studies now provide further independent evidence of this weakening. In August a paper by Christopher Piecuch of the Woods Hole Oceanographic Institution on the Florida Current – the part of the Gulf Stream system along the Florida coast – was published. Although continuous measurements of the current have only been available since 1982, Piecuch was able to reconstruct the strength of the Florida Current over the last 110 years from measurements of the sea level difference between the two sides of the current. To do so, he used 46 tide gauge stations in Florida and the Caribbean as well as a simple physical principle: the Coriolis force deflects currents in the northern hemisphere to the right, so that the water on the right side of a current stands higher than on the left. The stronger the current, the greater the difference in sea level. Comparison with measurements since 1982 shows that the method works reliably.

The result: the Florida current has weakened significantly since 1909 and in the last twenty years has probably been as weak as never before. Piecuch’s calculations also show that the resulting reduction of heat transport is sufficient to explain the ‘cold blob’ in the northern Atlantic.

This Monday, in Nature Climate Change a further study appeared, of researchers of Peking University and Ohio State University (Chenyu Zhu and Zhengyu Liu). For the first time, their paper provides evidence for an AMOC slowdown based on data from outside the North Atlantic. Model simulations show that a weakening of the AMOC leads to an accumulation of salt in the subtropical South Atlantic. This is due to the fact that strong evaporation in this region constantly increases the salinity, while the upper branch of the ocean circulation drains the salty water northwards, continually bringing in less salty water from the south. When this current weakens, the water in this region becomes saltier. This is exactly what the measured data show, in accordance with computer simulations. The authors speak of a “salinity fingerprint” of the weakening Atlantic circulation.

Video animation of ocean currents in the CM2.6 climate model of the Geophysical Fluid Dynamics Lab in Princeton:

In addition to these oceanographic measurements, a number of studies with sediment data indicate that the Gulf Stream circulation is now weaker than it has been for at least a millennium.

These current changes also affect Europe, because the ‘cold blob’ out in the Atlantic also influences the weather. It sounds paradoxical when you think of the shock frost scenario of the Hollywood blockbuster The Day After Tomorrow: but British researchers found that in summer the jet stream in the atmosphere likes to take a route around the south side of the cold blob – this then brings warm winds from the southwest into Europe, leading to heat waves there, as in the summer of 2015. Another study found a decrease in summer precipitation in northern Europe and stronger winter storms. What exactly the further consequences will be is the subject of current research.

However, the latest generation (CMIP6) of climate models shows one thing: if we continue to heat up our planet, the AMOC will weaken further – by 34 to 45% by 2100. This could bring us dangerously close to the tipping point at which the flow becomes unstable.

This article appeared originally in German in Der Spiegel: Das Golfstromsystem macht schlapp

171 Responses to “New studies confirm weakening of the Gulf Stream circulation (AMOC)”

  1. 1
    Russell says:

    Huge thanks to Stefan for rendering this in English- I know from interview experience that Der Spiegel’s idiom can defy translation..
    Roland Emmerich made his cinematc debut with a 1984 Berlin Festival Cli-Fi film, The Noah’s Ark Principle ( Das Arche Noah Prinzip) which he directed as his thesis at the Hochschule für Fernsehen und Film München

  2. 2
    Brian Mapes says:

    The time series I expected the post to have is here.
    https://www.nature.com/articles/s41467-020-17761-w/figures/2

  3. 3
    mike says:

    Seems like it might be bad news.

    I think it has something to do with this:

    Daily CO2

    Sep. 16, 2020: 411.66 ppm

    Sep. 16, 2019: 408.64 ppm

    We should flatten that curve.

  4. 4
    Ken Fabian says:

    Would a shutdown be followed by a restart or would different, more localised circulations emerge? I did wonder if an AMOC shutdown with regional cooling, followed by restart and regional warming could become a longer term oscillation that persists.

  5. 5
    Nemo says:

    There is only one oceanographer who has been continuosly measuring gulf stream velocity for 40 years , thomas rossby , and he says slowing of the gulf stream is pure nonsense

    [Response: Nice discussion of Tom Rossby’s work in further comments below. Let me add that we showed Rossby’s measured trend in our RC article of 2018 in Fig. 4. It does not contradict our findings if you compare like with like, i.e. the same time intervals. Can you give a source for your alleged quote from Tom please? -Stefan

  6. 6

    This recent paper is a curveball:

    “Yu, Y., Liu, H., Lin, P. & Lan, J. “The impact of oceanic processes on the transient climate response: a tidal forcing experiment” Acta Oceanologica Sinica 39, 52–62 (2020).

    They find a significant change in models of AMOC circulation once tides are added.

    “In the present study, the impact of tidal forcing on the sensitivity of transient climate change is investigated using two sets of experiments with and without tidal forcing in a coupled climate model. After introducing the tidal forcing, we found that the TCR is reduced from 2.32 K to 1.90 K.

    In the paper they state “we do not focus on explaining why the AMOC was enhanced in Exp_Tide” but note that Munk & Wunsch anticipated it years ago.

    “Munk and Wunsh (1998) pointed out that the winds and tides are the only possible source of mechanical energy to drive ocean thermohaline circulations. The box model simulations also supported this new viewpoint (Huang, 1999; Guan and Huang, 2008; Shen and Guan, 2015). It is estimated that tides can provide 1 TW energy to drive the interior mixing, and the remaining energy comes from winds. In our recent work (Yu et al., 2016), we introduced eight barotropic equilibrium tides into an ocean general circulation model. We also found that the upper cell of the AMOC is significantly changed. Therefore, we will investigate the change in the OHU and the TCR in the coupled model with and without the tidal forcing in the present paper. The purpose of the present study is twofold: to fully understand the role of the tidal processes in the climate system and to understand the behavior of our coupled model when the AMOC changes.”

  7. 7
    Carbomontanus says:

    Yes, I have long been looking for a plausible physical explaination of that “cold blob” southeast of Grønland.

    On the other side, there is a most remarkable hotspot or hot blob at the islands of Severnaya Zemlya, the most mysterious islands in the world, hidden and forgotten in fogs and ices until quite recently. And not on the world maps until the days of Stalin. Today you can easily sail arond them in the season.

    I have kept Severnaya zemlya as my personal landmark of climate change now for years.

    At the same time, the north-western ices and seaways do not seem to thaw up equally fast. Roald Amundsen would hardly have got all the way to Gjøa haven in the first season now 2 years ago, and he froze tight at Cape Tsjeljugin in 1918, where Nordenskjøld and later Nansen had passed easily through under sail and by some steam, quite much earlier.

    Stalin shall have borrowed Graf Zeppelin to map Severnaya zemlya, and gave them very proud names like Bolcevik, October revolutin, Komsomolets, and Pioneer island.

    Umberto Nobile with his airship ITALIA tried to get there from Ny Ålesund in a test flight for the north pole, but had to return in the fogs.

    In this year 2000 you can easily sail around Franz Josefs Land also, by very good clearence.

    S.K.

  8. 8
    Mr. Know It All says:

    My notes on the OP article:

    1×10^15 Watts with a flow of 20×10^6 cu.m./sec gives a delta T of 12.67 C (22.8 F). Souunds fairly reasonable.

    Quote: “Even Hollywood took up the subject in 2004 in the film “The Day After Tomorrow” by the German director Roland Emmerich. However, there were no measurement data that could prove an ongoing slowdown.”…..

    So scientific papers here on RC are now citing Hollywood movies as evidence of AGW? Really?

    Quote: “Although the data show a weakening of the current system, the measurement series is still too short to distinguish a possible climate trend from decadal variability.”

    That’s the bottom line, not enough evidence, thus the title which says the weakening is “confirmed” is misleading at best. No, you cannot extrapolate out a 14 year measurement into needed 30 years of data needed to be considered “climate” as I have been reminded approximately 1,000 times on this website, right BPL? :)

    Quote from IPCC: ” “Observations, both in situ (2004–2017) and based on sea surface temperature reconstructions, indicate that the Atlantic Meridional Overturning Circulation (AMOC) has weakened relative to 1850–1900.””

    This is the type of malarkey I’d expect from the IPCC. There were essentially NO measurements of any temperatures in the Atlantic during that period. In fact, per this article, they didn’t even start to gather data until 2004.

    Quote: “…. was able to reconstruct the strength of the Florida Current over the last 110 years from measurements of the sea level difference between the two sides of the current.”

    That is not science – it’s his best guess, an estimate that has as much probability of being wrong as it does being right. I do this type of estimate all the time for back of the envelope calculations.

    Quote: “The result: the Florida current has weakened significantly since 1909…”

    Really? Since 1909. I’d like to see the math that came up with that date! Seems fairly precise given there were no measurements until 2004, no?

    Quote: “However, the latest generation (CMIP6) of climate models shows one thing: if we continue to heat up our planet, the AMOC will weaken further – by 34 to 45% by 2100. This could bring us dangerously close to the tipping point at which the flow becomes unstable.”

    It could all turn out to be true, but at this point there just isn’t sufficient data to say. Science is slow. How long did the debate over a flat earth go on?

  9. 9
    Jan says:

    Thanks for the nice Article.

    Several issues I have. One is that the western boundary currents are warming about 4x the rate of the ocean surface. Therefore, a decline in energy content of the AMOC would be interesting and not only in strength measured in volume.

    The other is that Greenland is melting from the surface which has increased tremendously during the last decades. Greenland’s ice losses are the greatest in the southern area. That’s where the cold blob is. And meltwater is less dense and stays on the surface therefore the cold blob is at least to a good part an outcome of ice loss.

    I did not read the studies, maybe they address these issues. So my main points are that the decline in energy content is in the median time range the main issue and how much of the cold blob is due to meltwater (if the AMOC slows down it can not cool down the region below normal (just the amount of heating gets smaller). The cold blob is cooled down water below normal values which should be because of meltwater). Moreso, because this is also the region with huge sea ice losses (leads also to meltwater at the surface).

    ALl the best

    Jan

  10. 10
    MA Rodger says:

    Nemo @5,
    There appears to be a few errors in what you write which, I’m sorry, make your comment @5 to be the “pure nonsense”
    Thus is is not 40 years that Rossby has been “continuosly” measuring the strength of the Gulf Stream (although Rossby has been doing measurements of ocean currents for over 40 years). Back in 2014, that ‘measurement’ period only spanned 20 years which I’m sure does not make Rossby the “only one oceanographer” you suggest.
    At that time Rossby’s measurements did not find evidence for a slowdown (with the research paper being discussed here) saying his results contradicted other findings.
    But he did not brand a slowdown as being “pure nonsense.” Instead, in the 2014 paper he discusses possible reasons for the contradictory data while in the 2014 commentary he is quoted saying “there is good reason to be concerned about the long-term stability of the Gulf Stream, since if the Gulf Stream were slowing, a decrease in the flow of warm water to the northern North Atlantic could cause significant cooling in parts of Europe.”

  11. 11
    Ann Kah says:

    @Nemo (5) The only reference I find for that is from 2014, and it sounds as if Rossby based his conclusion only on direct current speed measurements. The article here mentions the small amount of information from direct measurements but describes other methods of analysis as well, which were neither acknowledged nor addressed by Rossby in the reference I found.

  12. 12
    Ric Merritt says:

    I’m pretty sure Rossby, though semiretired, still studies the gulf stream, and is not convinced, at least yet, that he has evidence for slowing. If he said that claims of slowing are “pure nonsense”, you’d better provide a reliable link for that.

  13. 13
    David Karoly says:

    Stefan, thanks for this clear and helpful update. Something that is not so clear in the article is the distinction between the Gulf Stream, which usually refers to the near-surface current system in the North Atlantic transporting water northward off the North American east coast, and the Atlantic Meridional Overturning Circulation (AMOC), which refers to the deep overturning circulation in the North Atlantic. They are closely linked but they are not the same. The Gulf Stream is driven in part by the surface westerly winds from North America across the North Atlantic, which may be independent of variations in the AMOC. Some of the observational data and analysis described in this article may be better for documenting changes in the AMOC and some may be better for documenting changes in the Gulf Stream.

    Oceanographers such as Stefan will be able to correct what I say here.

  14. 14
    Jeffrey Davis says:

    #5 “There is only one oceanographer who has been continuously measuring gulf stream velocity for 40 years …”

    Then he should be able to prove the study wrong.

  15. 15
    nigelj says:

    Mr. Know It All @8, spouts pure nonsense. A ten second google search shows Atlantic ocean temperatures have been measured by ships using buckets, from approx. 1850.

    https://www.ncei.noaa.gov/news/planet-postcard-bucket-full-data#:~:text=Measuring%20Sea%20Surface%20Temperature%20with%20Buckets&text=They%20then%20recorded%20the%20temperature,%2C%20to%20New%20Orleans%2C%20Louisiana.

    “Science is slow. How long did the debate over a flat earth go on?”

    Hilarious. A long time, because we didn’t have a thing called science back then perhaps?

  16. 16

    KIA 8: No, you cannot extrapolate out a 14 year measurement into needed 30 years of data needed to be considered “climate” as I have been reminded approximately 1,000 times on this website, right BPL? :)

    BPL: It depends on the individual series and how long it takes for the standard deviation to stabilize. 30 years is the figure usually used for global temperature based on this analysis:

    http://bartonlevenson.com/30Years.html

  17. 17
    Susan Anderson says:

    I thought it might be useful to check. Here’s Mike Mann on the “controversy” (I’ve included the full item):

    Some critics have tried to make hay over a previous article from last year by URI Graduate School of Oceanography scientist Tom Rossby (see: http://www.gso.uri.edu/b…/rossby-gulf-stream-is-not-slowing/ ) they claim contradicts our recent Nature Climate Change study finding evidence for a long-term slowdown of the Atlantic Meridional Overturning Circulation (“AMOC”). [Tom incidentally is the son of the great meteorologist Carl-Gustaf Rossby of “Rossby wave” fame: http://en.wikipedia.org/wiki/Carl-Gustaf_Rossby . He also happens to be a friend. He is one of leading physical oceanographers of our time. His scientific work is extremely thoughtful, careful, and solid].

    Rossby employs direct measurement of Gulf Stream transport using a ship-board acoustic Doppler current profiler (ADCP) over the interval 1993-2012. I have no reason at all to doubt Rossby’s findings. And they do *not* conflict with our own findings (though some have misleadingly sought to assert they do) for two fundamental reasons:

    1. One man’s signal is another man’s noise: Over the relatively short interval (1993-2012) in question, we too find little or no net trend (!). The trends that we identify in our article are longer-term in nature, and are corroborated by independent studies and independent data (e.g. Nitrogen isotope data from corals) as documented in our article.

    2. What Rossby is measuring is largely associated with the wind-driven boundary current of the subtropical horizontal ocean gyre, the warm poleward current that hugs the coastline of the southeastern U.S., the current that *physical oceanographers* refer to as the “Gulf Stream”. This is rather different from what we are looking at, which is what oceanographers instead refer to as the “AMOC” and more specifically, the “thermohaline circulation” (sometimes also called the “conveyor belt” because of the shape of the circulation cell, which in the Atlantic carries warm waters northward near the surface and cold waters southward at depth, thus providing a net transport of heat poleward). That vertical overturning circulation is driven instead by lateral density contrasts that arise due to variations in temperature and salinity. The shallow component of this ocean circulation pattern does not recirculate within the subtropical gyre and instead continues northward across the North Atlantic toward Iceland and Europe. That component is typically referred to as the “North Atlantic Drift” by oceanographers. It is not the “Gulf Stream”. But the problem: in common parlance (and numerous news articles and reports), it *is* referred to as the “Gulf Stream”.

    So in short, we and Rossby aren’t really looking at the same current system (though one might think so due to the confusing and often inconsistent use of the “Gulf Stream” terminology), and even if we were, both studies agree that there was little or no trend over the quite short interval of 1993-2012.

    It is always useful to question new studies, and subject them to the full scientific scrutiny they deserve. And Carl Sagan’s famous maxim “the more extraordinary the claim, the more extraordinary the evidence must be” certainly applies. But bad faith efforts to confuse the public by erroneously conflating two very different findings has no place in the public discourse over the science and its implications.

    https://www.facebook.com/MichaelMannScientist/posts/some-critics-have-tried-to-make-hay-over-a-previous-article-from-last-year-by-ur/873222562733947/
    [Facebook, can’t live with it; can’t live without it]

  18. 18

    nigelj said:

    ““Science is slow. How long did the debate over a flat earth go on?”

    Hilarious. A long time, because we didn’t have a thing called science back then perhaps?”

    It’s actually more related to the fact that earth sciences can’t do controlled experiments like other scientific disciplines (e.g. condensed matter physics, chemistry, etc) are allowed to perform. So like back then, the test of time is the only way to validate a model.

    Here is a hilarious interview with Physics Nobel laureate Murray Gell-Mann where he describes how glacially slow the science of geology proceeds:

    “Because the theories people have put forward about the phenomenon are unsatisfactory, that doesn’t mean the phenomenon doesn’t exist. But that’s what most American geologists did until finally their noses were rubbed in continental drift in 1962, ’63 and so on when they found the stripes in the mid-ocean, and so it was perfectly clear that there had to be continental drift, and it was associated then with a model that people could believe, namely plate tectonics. But the phenomenon was still there. It was there before plate tectonics. The fact that they hadn’t found the mechanism didn’t mean the phenomenon wasn’t there. Continental drift was actually real. … And as that evidence accumulated, the American geologists voted more and more strongly for the idea that continental drift didn’t exist. The more the evidence was there, the less they believed it. Finally in 1962 and 1963 they had to accept it and they accepted it along with a successful model presented by plate tectonics….

    I’m struggling with a similar problem in identifying oceanic variability with tidal processes. As the precise repeat period of a tidal cycle can last a few hundred years (depending on the detail desired) then any attribution of an observed behavior with a tidally-modeled process may also require that long to validate. That’s unless scientists are willing to experiment with cross-validation techniques that use historical data instead of future data. The future is a valuable commodity that we can’t always wait for to unfold.

  19. 19
    Michael Sweet says:

    Stephan or anyone else who knows:

    How will the slowing of the AMOC affect the melt rates of Arctic Sea Ice and the Greenland Ice Sheet? Will the slowing mean less energy is transferred north and mean slower melting of these areas? Or will deeper circulation continue to bring heat north to melt the bottom of the Ice Sheet? Could the sea ice end up melting slower while the Ice Sheet melts faster? No effect at all? Is there a paper I could read on this topic?

    I remember Dr. Hansen suggesting that deep heat transfer would still affect the ice sheet but that was a long time ago and knowledge might have changed.

  20. 20

    Yes, thanks for an interesting article.

    Too bad KIA had to chime in @8 with a bunch of foolish hooha too dumb to even bother with. It was a bit funny, though, when he essentially said “That’s not science, that’s what I do!” Could be the germ of some self-recognition in there.

    Who’da thunk?

  21. 21
    Susan Anderson says:

    Kevin McK, we all know KIA’s nonsense, but I was surprised by Nemo.

    A useful corrective from Mike Mann from my extended quote above:

    bad faith efforts to confuse the public by erroneously conflating two very different findings has no place in the public discourse over the science and its implications.

    Though perhaps “bad faith” is too generous.

  22. 22
    Phil Scadden says:

    “Science is slow. How long did the debate over a flat earth go on?”

    Since there was strong evidence of spherical earth from around 4th century BC, can you produce evidence of any widespread debate among educated classes in the west that earth was flat since then? (You do know that Columbus was not fighting flat-earthers but debating the size of the earth? He needed a small earth to convince his patrons that you could say to India by going west in a reasonable time).

  23. 23
    Christopher Hogan says:

    Can anyone provide a back-of-the-envelope estimate of the impact of projected year-2100 AMOC slowing on US East Coast sea level?

    I recall that the little “hiccup” the Gulf Stream took in 2012 lead to a measurable short-term increase in sea level on US east coast tidal gauges — several inches’ in two or three months. And that the gradual slowdown has been adding to East Coast sea level rise.

    My understanding is that, at present, there’s about a 3′ to 4.5′ difference in sea level height between the eastern and western edges of the Gulf Stream, as it moves up the US east coast.

    I’m just asking the obvious question: Would a 40% slowing by 2100 result in a 40% reduction in the existing height difference? And so, would it add another 1.5′, say, on top of generally projected sea level trend? That would be a material difference.

  24. 24
    CCHolley says:

    RE. Mr. Know Nothing @8

    How long did the debate over a flat earth go on?

    Actually intellectuals have known since the time of the ancient Greeks that the Earth was round. There really wasn’t much of a debate as it is quite easy to deduce from observations. Observations like a ship’s mast appearing first from the shore as it approaches and likewise mountaintops appear first when sailing towards land. Also it was noted that the appearance of the stars overhead change as one moves north or south which would not happen if the Earth were flat. It was also observed and measured that the angle of a shadow is different at noon depending on where you are north or south, it would remain the same on a flat Earth. The circumference of the Earth was actually quite accurately calculated around 300 BC based on this phenomena. And, it was easily noted that the Earth casts a round shadow on the moon during an eclipse. *Science* never ever theorized that the Earth was flat and in *science* it was NEVER debated. Any denial of a round Earth was, and still is, from ignorant superstitious people. Much like climate denialism.

  25. 25
    Mack says:

    @ 24 CCHolley,
    “Any denial of a round Earth was, and still is, from ignorant superstitious people. Much like climate denialism.”

    You mean the ignorant and superstitious people like the President of the Flat Earth Society who believes in “climate change”?

  26. 26

    #25, Mack–

    Fools can ‘believe in’ true things.

    For instance, you seem to believe the Earth is round.

  27. 27
    Victor says:

    Stefan, I’m wondering whether you can provide us with evidence that a simple increase in average global temperature of 1 degree Celsius over a period of a hundred years can be responsible for ALL of the following: widespread flooding, widespread forest fires, widespread droughts, ever more frequent and powerful tornadoes, loss of arctic sea ice, undermining of the West Antarctic Ice Sheet, erosion of Greenland’s ice sheets, widespread species extinction, extreme heatwaves, ever accelerating sea level rise. And let us not forget the weakening of the Gulf Stream circulation that alarms you so much.

    Please explain what sort of science could possibly link all the above to one particular cause, especially since the driving force deemed responsible is so utterly miniscule. Earth’s temperatures range from -25 degrees Celsius in the Arctic regions to 45 degrees Celsius at the equator. How could a difference of 1 degree possibly be responsible for all these drastic and presumably dangerous outcomes? While each of these alarming effects has been studied individually, I’m wondering whether the convergence of all these very different outcomes has ever been subject to critical review.

  28. 28

    Kevin McKinney said:

    “For instance, you seem to believe the Earth is round.”

    You mean spherical, and yes, it is not uniformly spherical. Because of that imperfection, the Earth is subject to torques applied by the moon and the sun. This leads to precise corrections to the Earth’s length of day and to the cycle of the Chandler wobble. The latter is where the real scientific arguments take place, not of the flat earth kind.

  29. 29
    Karsten V. Johansen says:

    Maybe off-topic, but just as a socio-psychological comment concerning the latest postings here. Climate contrarianism differs from flat earth belief on a very central point: Climate contrarianism is almost always closely connected with some form of fossil fuel addiction. Therefore the “arguments” are routinely intrinsic contradictory, and that generally doesn’t bother contrarians at all, in case revealing that their motivation isn’t scientific.

    The most dangerous contrarians are the practical and tactical ones, often called the lukewarmers. Those who pretend not to be contrarians, they pretend to be with the science all the way. But: they just silently sabotage any kind of effective cuts to the use of fossil fuels. By doing this they also very efficiently undermine popular belief in the scientific warnings, because a lot of people look at them, fx. Obama, one day saying “I’m deeply concerned about the disappearance of the arctic sea ice”, and then the next day boasting “That whole, suddenly America’s like the biggest oil producer and the biggest gas [producer thing]—that was me, people.” https://apnews.com/5dfbc1aa17701ae219239caad0bfefb2 .

    Flat earthers, creationists etc. on the other hand aren’t normally (except for charismatic charlatans) motivated by economic interests, neither short-term nor long-term. They are just religious fanatics and/or naivists, maybe motivated by powergains/making career inside churches etc., or they are “trolls”, people who like to be destructive for the sake of it.

  30. 30
    Mack says:

    @26 Kevin McKinney,

    Sure, I believe the Earth is round.

    There are also fools who believe that the ATMOSPHERE of Earth is keeping the oceans in a liquid state. ie not all frozen solid, with an average temperature of -18 deg C.

    You’re not one of those fools, are you, Kevin ?

  31. 31
    William B Jackson says:

    @30 Mack you mean the fools who believe in reality?

  32. 32
    nigelj says:

    Victor @27 indulges in the “argument from incredulity fallacy”. This is the same Victor who claims to be a master of “critical thinking”. Sad!

  33. 33
    Mr. Know It All says:

    27 – Victor
    Don’t worry about AGW Victor. 1 or 2C rise will be welcome in much of the world. Also, FYI, you can replace that -25C in your comment with -89.2C. ;)

    Life thrives at extreme temperatures in the hot atmosphere of Venus, which is hotter than the hinges on the gates of heII! Oh yes it does, according to the latest science. Don’t be a denier! Leftist NY Times says it is true!

    https://www.nytimes.com/2020/09/14/science/venus-life-clouds.html

    “….But with powerful telescopes, they have detected a chemical — phosphine — in the thick Venus atmosphere. After much analysis, the scientists assert that something now alive is the only explanation for the chemical’s source.”

    “For the last two decades, we keep making new discoveries that collectively imply a significant increase of the likelihood to find life elsewhere,” said Thomas Zurbuchen, the head of NASA’s science directorate, who helps select missions to explore the solar system. “Many scientists would not have guessed that Venus would be a significant part of this discussion. But, just like an increasing number of planetary bodies, Venus is proving to be an exciting place of discovery.”

  34. 34
    CCHolley says:

    Paul Pukite @28

    You mean spherical, and yes, it is not uniformly spherical.

    Yes technically, it would be more accurate to call the Earth spherical or perhaps close to spherical, but just for fun note that in common parlance ‘round’ has a broad definition and is acceptable for describing something that is close to spheroid like the Earth.

    From the Oxford Dictionary:

    Round
    2. Shaped like a sphere ‘a round glass ball’

    The Thesaurus lists such synonyms for ’round’ as spherical, oval, elliptical, circular, spheroid, and cylindrical.

  35. 35
    CCHolley says:

    RE. Victor @27

    Sheesh, it is hard to believe that Victor could get any dumber in his posts here at RealClimate, but this one reaches a new all time low for stupidity.

  36. 36
    jgnfld says:

    @27 vic

    Wonderful example of argument from incredulity.

  37. 37

    V 27 wonders how 1 K can account for all kinds of climate damage, and cites the wide variations in temperature over Earth’s surface.

    We’re talking about the mean global annual surface temperature (Ts), Victor, not the weather. It’s a measure of the energy in the entire climate system. The difference between now and a mile of ice over Chicago and New York is only 6 K. 1 K in Ts is a huge, huge difference.

  38. 38

    M 30: There are also fools who believe that the ATMOSPHERE of Earth is keeping the oceans in a liquid state. ie not all frozen solid, with an average temperature of -18 deg C.

    BPL: That’s because it is, Mack. Without the greenhouse effect the Earth would be frozen over. Want the math?

  39. 39
    Ray Ladbury says:

    Weaktor: “Stefan, I’m wondering whether you can provide us with evidence that a simple increase in average global temperature of 1 degree Celsius over a period of a hundred years can be responsible for ALL of the following: widespread flooding, widespread forest fires, widespread droughts, ever more frequent and powerful tornadoes, loss of arctic sea ice, undermining of the West Antarctic Ice Sheet, erosion of Greenland’s ice sheets, widespread species extinction, extreme heatwaves, ever accelerating sea level rise. And let us not forget the weakening of the Gulf Stream circulation that alarms you so much.”

    It’s called physics. Maybe you should look it up.

  40. 40

    #30, Mack–

    Keep digging, Mack. Got to be a bottom somewhere, right?

    You definitely put the ‘DK’ in ‘idk’.

  41. 41
    Mal Adapted says:

    Karsten V. Johansen:

    Climate contrarianism differs from flat earth belief on a very central point: Climate contrarianism is almost always closely connected with some form of fossil fuel addiction.

    This is an important point about climate-science deniers vs. other crackpots: AGW-deniers are often unconsciously but transparently motivated by economic self-interest. That’s supported by our knowledge of denialism as a psychological defense mechanism. The deniers have been happily socializing and deferring their private climate-change costs all their lives, and don’t wish to be told they have to start paying as they go. Rather than admit to being responsible for third-party losses, they simply reject the evidence. IMHO, that’s not hard to understand.

    KVJ:

    The most dangerous contrarians are the practical and tactical ones, often called the lukewarmers. Those who pretend not to be contrarians, they pretend to be with the science all the way.

    This is a succinct description of lukewarmism, but pertains as well to the “soft denial” of Michael Hoexter (h/t Bill Henderson), of which anyone with the slightest link to the global economy is guilty. That of course includes all RC commenters. FWIW, I think the difference is that a large majority of us are willing to internalize our marginal emissions costs if everyone else does 8^). Actually, that’s what Hardin meant by “mutual coercion, mutually agreed upon”. It can be in the form of government authority (e.g. carbon tax), or as Ostrom pointed out, any joint stakeholder agreement with practical teeth (e.g. carbon-neutral commitments by utility co-ops).

    KVJ:

    But: [lukewarmers] just silently sabotage any kind of effective cuts to the use of fossil fuels. By doing this they also very efficiently undermine popular belief in the scientific warnings, because a lot of people look at them, fx. Obama, one day saying “I’m deeply concerned about the disappearance of the arctic sea ice”, and then the next day boasting “That whole, suddenly America’s like the biggest oil producer and the biggest gas [producer thing]—that was me, people.” https://apnews.com/5dfbc1aa17701ae219239caad0bfefb2 .

    Good insight, and it describes any bluish elected official in the US, who must placate all the soft denialists that support him as long as he doesn’t try to make them pay full price for their comfort and convenience.

    Thanks, Karsten. A Norwegian understands America’s peculiar institutional AGW-denial as well as any of us.

  42. 42
    Mal Adapted says:

    Mack:

    You’re not one of those fools, are you, Kevin ?

    No doubt this has already occurred to you, Kevin, but I think Mack’s just messing with you by this point.

  43. 43
    Susan Anderson says:

    @Karsten V. Johansen

    While agreeing with the general substance of your argument, I would suggest a more subtle distinction. Contrarians in many cases object to the policy that would be necessary, which involves a complete change in our habits of consumption and all the exploitative wealth we take for granted. They address the source of the necessity, while many of us who are convinced by reality are at least a little hypocritical. [One often finds they have solar panels and drive more sustainable vehicles.]

    We are passive to the need to change how we regard exploitation of the planet’s air, water, and earth: all living creatures take from their surroundings, and we are reaching the limits of consumption. We might feel powerless in the face of the norms of our economy, which include waste and disposables as a given, in ever increasing quantities and often toxicity as well. We take climate injustice as a given, and as long as our air and water, housing and material goods, are available in a steady, sufficient stream, are unwilling to look more closely at the dynamics of consumption.

    The tactics of deception are woven through and through with revelations about policy problems with actually acting in time to save our future.

    I’m not recommending giving up, or apathy, which disguise laziness, but even the best communicators are baffled when it comes to what to do. Hope Jahren suggests using less and sharing more, and that’s about as good as I can come up with, but it’s not enough. We regard our standard of living as non-negotiable.

  44. 44
  45. 45
    Ray Ladbury says:

    Mr. Kia: Life thrives at extreme temperatures in the hot atmosphere of Venus, which is hotter than the hinges on the gates of heII!

    Dude, your selective gullibility is showing…again. Maybe this will help
    https://xkcd.com/2359/

  46. 46
    nigelj says:

    Susan Anderson @43, good points, but regarding “We regard our standard of living as non-negotiable.” No I think many people will make some changes, although with reluctance obviously and they need proof there’s a good reason. Some people have already reduced their carbon footprints. I have made some changes, I admit not as much as I could.

    The problem is related to this, and I think its called the first mover fallacy. I cant find where I read this but it goes something like this: Most people are reluctant to sacrifice any of their standard of living until they see others doing the same, because they think they alone will make no significant difference, and they also don’t want to be taken for suckers. As a result most people are reluctant to act and so nobody acts.

    The same principle might apply to corporations and countries. Eventually enough people do usually make some changes and things reach a tipping point but the process is very slow and not universal.

    This is why the climate problem is primarily political. We have to persuade politicians to do more to ‘force’ the issue, with things like new electricity grids and carbon taxes, which force everyone to change more or less in unison.

  47. 47
    Mack says:

    @ 31 William B Jackson
    @ 42 Mal Adapted
    @ 40 Kevin McKinney

    @ 38 BPL
    “That’s because it is, Mack. Without the greenhouse effect the Earth would be frozen over”

    You say ? BPL ? Here’s a thing see, BPL. The last time I looked at the sea from my house overlooking the bay, I noticed that the sea wasn’t frozen solid, but I’m reassured by you and all the experts, don’t worry, the ATMOSPHERE is keeping it nice and liquid. It’s a good job you and all the experts are telling me this, because, silly me, here I was thinking it was the SUN that melted ice.
    Are you sure you don’t think the Earth is flat, BPL ?

    ” Want the math?” you say ?

    I know the math. Maybe you and all the experts have made a mistake in “the math”
    Reality doesn’t always agree with “the math”.

  48. 48
    Killian says:

    43 Susan Anderson:we are reaching the limits of consumption.

    We are in overshoot, not approaching it.

    We might feel powerless in the face of the norms of our economy, which include waste and disposables as a given, in ever increasing quantities and often toxicity as well. We take climate injustice as a given, and as long as our air and water, housing and material goods, are available in a steady, sufficient stream, are unwilling to look more closely at the dynamics of consumption.

    Indeed. Simplicity scares the hell out of all of you, which is why I am so hated here. Well, that and for not putting up with the insults, lies and bullying. (Yeah, go check the comments 2006-ish to 2013-ish. It wasn’t like this – and it wasn’t me who changed.)

    The tactics of deception are woven through and through with revelations about policy problems with actually acting in time to save our future.

    You really mean economics here, which is exactly why our collective response has literally been insane.

    I’m not recommending giving up, or apathy, which disguise laziness, but even the best communicators are baffled when it comes to what to do.

    How can they communicate what they do not understand, don’t want to understand (as you demonstrate above), are unwilling to do, and given they are unwilling to listen to those who do know?

    Hope Jahren suggests using less and sharing more

    Oh! Hope Jahren does! OK… You mean the Hope Jahren that sees Nature as capital, which is well-intentioned but quite literally an insane approach to solving pour problems?

    Funny, you’ve been seeing my comments here for years about reducing consumption. Where’s my shout-out?

    Oh, right… If a PhD says it, it must be true – even if they say it nonsensically. Hope you figure out whom to listen to before it’s too late.

    But, then, you’d have to maybe give up your lattes.

    and that’s about as good as I can come up with, but it’s not enough.

    It is exactly good enough, and the only option, but you have to take it to its full regenerative conclusion: Commons.

    We regard our standard of living as non-negotiable.

    Who is this “we” you speak of? Sure as hell isn’t me.

    You’ve done a nice job of succinctly exploring the collective insanity.

  49. 49

    KIA 33: 1 or 2C rise will be welcome in much of the world.

    BPL: To idiots.

  50. 50

    KIA 33: Life thrives at extreme temperatures in the hot atmosphere of Venus

    BPL: No. It does not. The life which may be there exists in the clouds 50-60 km above the surface, where the temperature is cool enough for liquid water. When you see an article, it helps to read it, if you really want to know what it says.

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