By Robert Bradley Jr.
Ed. note: A recent peer-reviewed article in Nature (discussed here) has, once again, knocked this speculative “fat tail” hypothesis down to size. “Based on the here identified relationship and observation-based estimates of the past air-sea heat flux in the North Atlantic from reanalysis products,” the authors concluded, “the decadal averaged AMOC at 26.5°N has not weakened from 1963 to 2017 although substantial variability exists at all latitudes.”
Climate alarm is the name of the game for the government-led Climate Industrial Complex to keep the taxpayer grants going to the wind, solar, and battery rent-seekers. Nature is optimal and fragile, and the game is to throw hypotheticals against the wall to see what might stick. The mainstream media is hungry for a scary scenario too.
One perennial fear is a potential collapse of a crucial system of ocean currents known as the Atlantic Meridional Overturning Circulation (AMOC). A few scientists are ‘out there’ predicting an increasing chance of a collapse, but the consensus leans the other way. [1]
Forty-four scientists, including Michael “Climategate” Mann, published an open letter with ominous implications. “Recent research since the last IPCC report does suggest that the IPCC has underestimated this risk and that the passing of this tipping point is a serious possibility already in the next few decades,” the letter states. The missive closes with a call to action:
Recognizing that adaptation to such a severe climate catastrophe is not a viable option, we urge the Council of Nordic Ministers to (a) initiate an assessment of this significant risk to the Nordic countries and (b) take steps to minimize this risk as much as possible. This could involve leveraging the strong international standing of the Nordic countries to increase pressure for greater urgency and priority in the global effort to reduce emissions as quickly as possible, in order to stay close to the 1.5 °C target set by the Paris Agreement.
The media loved it. “Key Atlantic current could collapse soon, ‘impacting the entire world for centuries to come,’ leading climate scientists warn,” wrote Sascha Pare in LiveScience. “How much should you worry about a collapse of the Atlantic conveyor belt?,” asked Bob Henson at Yale Climate Connections.
Carl Wunsch Rebuttal
Are the risks of a collapse of the dominant mechanism of northward heat transport in the North Atlantic, ushering in record cold, a real threat? Has it been “greatly underestimated” as the above letter states? In such instances, a good second opinion is needed, and Carl Wunsch of MIT is about as good as one can get.
I emailed Professor Wunsch with the query:
Many years ago, Dick Lindzen gave me your address to ask about the fear of a disruption of the conveyor belt in regard to the Atlantic Meridional Overturning Circulation. You expressed doubt back then.
This alarm is in the air today, and I wondered if you had some thoughts on this post (below) to share on LinkedIn where a debate is taking place.
Among the many reasons why we ought to cut climate-warming greenhouse gas emissions as quickly and sharply as possible, the weakening of a system of ocean currents known as the Atlantic Meridional Overturning Circulation, or AMOC, ranks high indeed. Several key scientific papers over the last couple of years have put this long-percolating climate concern back on the front burner. It’s hard to overstate how widespread and calamitous the impacts could be if this conveyor belt were to collapse – and it’s a process that could begin in the next several decades, if the new work is on target.
He responded:
I’m aware of the fuss going on about the AMOC. Indeed I co-authored a paper about it not long ago (I’ve attached it). It’s somewhat technical.
To clarify however: I am *not* a climate skeptic, and I regard the threat of major climate change as very real and very worrisome. In that context, one can argue that alarming the public about elements such as the behavior of the AMOC could lead to useful actual political and scientific/engineering progress and precautions.
Where I become conflicted is when the particular science is mis-interpreted and mis-understood. Turning the AMOC on and off as an explanation of major past and possible future change has become a go-to-story for people who want a simple explanation of a very complicated system. [Wallace] Broecker [here] did the world a great dis-service with his advocacy of the “conveyor belt” which leads people to think they understand a system which looks nothing like his picture (a memorable graphic however).
There are lots of issues connected with the fuss over the AMOC. Amongst them, prominently, are the use of numerical models which produce ocean circulations that are far from what we actually observe. How seriously should one take their “predictions”? That the climate can change dramatically from what we have known for the last several hundred years is a fact, and a very worrisome fact at that. Does that mean the AMOC stories in the media are correct?Climate is a global phenomenon. Consider a hypothetical situation: turn the North Atlantic Ocean abruptly into all land. Zero AMOC; removal of a major current system. How does the climate system adjust? At the present time, the Earth is in near thermal balance (radiation incoming from the sun is almost equal to that radiated back to space—the small excess of incoming over outgoing is the global warming phenomenon). Physics suggests that the system would adjust to the removal of the North Atlantic by ultimately re-establishing global near-heat balance.
How does that happen? Change in clouds? Change in ocean circulation? Change in distribution of ice sheets? Change in atmospheric circulation? All global. How long does it take (years, decades, centuries)? What will the climate be like during the transition? We do not have numerical models with the demonstrated skill to answer such questions. Could be terrible, however. Suppression of the AMOC, should it happen, raises precisely the same global questions with the added complication that the North Atlantic circulation itself would also change.
Isn’t it worth taking some precautions? It’s an insurance problem in the same sense that I would rewire my house if an electrician told me that the existing wiring could cause a fire (not that a fire *will* happen; only that we know it could).
Comment
We live at a time when climate scientists do not want to be labeled a skeptic or denier, yet honest scientists are still doing their duty to weigh in against undue alarmism. (Note the beginning and end of Wunsch’s reply above.)
Also note that how the Deep Ecology notion of an optimal, stable, fragile climate is the default thinking of so many natural scientists. The idea that the human influence on climate could be positive and even a ‘fat tail’ good (such as cancelling out a series of volcanoes or a natural global cooling) is not part of the analysis.
[1] Atlantic Meridional Overturning Circulation (AMOC) describes the movement of water from north to south and back from south to north in the Atlantic Ocean. This circulation is responsible for warmth in different parts of the world and carries essential nutrients for ocean life.
The question is whether this (very slow) process is slowing down because of anthropogenic warming of the water, which would cause droughts in South Africa and sea level rise in the eastern U.S.
Source: What is the Atlantic Meridional Overturning Circulation (AMOC)?
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A non-skeptical scientist is not a scientist!
I read somewhere that the difference between a skeptic and a denier is that the skeptic would like to discuss meaningful critical facts in regards to an idea/hypothesis/theory
So if you are not a skeptic, are you sure that you are not denying something rather unpleasant?
Rahmstorf realclimate blog is rather critic of the article mentioned above -a climate skeptic by my definition- and that´s okay.
What is not okay is that he then proposes a rather absurd idea (using CMIP5 models rather than the newer and better CMIP6 models which do not reproduce his idea at all) and not one of that crowd says word about that . . you can witness a solid denial that anything could be wrong about that idea!
Carl Wunsch is a skeptic of alarm, but as Robert Bradley suggests he is aware of how the appearance of such can be poison to his career. He was featured in The Great Global Warming Swindle years ago, but became alarmed that he was portrayed as a skeptic of the “crisis” so he loudly denounced his heresy and did not appear in a subsequent version of the video. Courage is not one of his traits, to be sure. However, even a diluted skepticism is better than none.
‘Recent research’. Well, so much for the ‘climate science is settled’ meme.
The real problem is, all the observational science says (e.g. RAPID Buoy array) says nothing is happening with AMOC. So ‘recent research’ means only climate models. Hint. Climate models can never comprise true scientific research. Yet climate alarmists have perpetrated this false idea for decades, including movies like ‘Day after tomorrow.’
Some other notable ‘settled climate science’ canards:
Isn’t there such a thing as inertia? Never have I ever heard it mentioned. It would seem to me that this would have an impact.
Art Bell and Whitley Strieber deserve a hat tip here, for their 1999 book The Coming Global Superstorm which sparked the sudden-glacier-disaster movie “The Day After Tomorrow”.
In their book, in order to stop the AMOC so that a stalled curtain of warm air surrounded the poles trapping a tremendous mass of frozen Arctic air until it all escapes all at once and flash-freezes the entire northern hemisphere, they first had to melt all the glaciers to dilute the Atlantic’s salinity.
Bell and Strieber’s speculative hypothesis has a more likely chain of causality than Michael Mann’s “44 scientists” have come up with.
Since we’re already 11,000 years into an interglacial warming period, and the ice caps haven’t melted yet, perhaps the real “tipping point” that Mann’s 44 “scientists” should be warning us about is the natural return of planetary glaciation in about 25,000 years.
The “rapid” return to glaciation started 500 years ago when the date of orbital aphelion first occurred later than the boreal summer solstice in the present cycle. Northern hemisphere peak solar intensity is on the increase; northern ocean basins are warming fast and new snowfall records are a feature of weather reporting.
https://www.msn.com/en-us/weather/extreme-weather-events/see-it-record-snowfall-buries-parts-of-japan/ar-AA1yuNUF
Snow begins it journey to land from the oceans. Warmer oceans mean more snow.
Love these Bad AI/Photoshop images of Liberty up to her eyeballs in Water or Ice. If all the Ice in the world were to melt, Antarctica, Greenland and Glaciers, sea levels could only rise 220 feet…about half way up Liberty’s torso. But while Ice is possible, during the last glaciation grinding ice fields did cover Central Park but Sea Levels were 400+ feet lower.
I tried to post a comment on the RealClimate discussion, but that was about 15 hours ago, and it still hasn’t appeared, so perhaps they didn’t like what I had to say:
There’s no known mechanism by which global warming could significantly weaken the AMOC and/or Gulf Stream.
The driving mechanism for thermohaline circulation is that evaporation and cooling makes surface water in the northern North Atlantic saltier and denser than elsewhere, so it sinks. What goes down must come up, and the water eventually rises again in the tropics, roughly a millennium later.
During glaciations those currents are apparently intermittent, which causes huge climate variations, especially in northern Europe. Those variations are called Dansgaard-Oeschger cycles, and they dwarf recent climate change.
It is generally believed that Dansgaard-Oeschger cycles are, at least mostly, caused by meltwater surges in the northern North Atlantic, perhaps due to changing ice dams diverting meltwater from the great northern ice sheets. Fresher water is less dense than saltier water, so adding fresh meltwater in the northern North Atlantic prevents it from sinking, thus slowing or halting the AMOC.
https://www.nature.com/scitable/knowledge/library/abrupt-climate-change-during-the-last-ice-24288097/
https://archive.is/aUi9R#selection-415.0-419.271
https://judithcurry.com/2017/02/17/nature-unbound-ii-the-dansgaard-oeschger-cycle/
But Dansgaard-Oeschger cycles don’t happen during interglacials, like our current Holocene. That’s presumably because without the great northern Laurentide & Fennoscandian ice sheets there’s no source for the huge influxes of freshwater into the northern North Atlantic which would be required to halt or appreciably slow those currents.
When I say “huge” I mean really, really yuuuge. Some time back I did some calculations to estimate the effect of diverting the mighty Mississippi River out the Saint Lawrence Seaway, and concluded it would have a negligible effect on the Gulf Stream and AMOC.
I tried to post another comment on the RealClimate discussion, this time with no links. It hasn’t appeared, either. This is what I wrote:
G.F. Nirchard wrote, “The arguments about the need to burn oil because we might starve people are nonsense because only about 15% of global fossil fuel use is for food production and distribution.”
The fact that only a small percentage of fossil fuel use is for food production and distribution does not mean that only a small percentage of the food produced is thanks to fossil fuels. It just means that fossil fuels are also used for many other things.
For the first time in all of human history, catastrophic famines are fading from living memory. That’s a very, very Big Deal. For comparison:
● COVID-19 killed about 0.1% of the world’s population
● The catastrophic 1918 flu pandemic killed about 2%
● WWII killed 2.7% of the world’s population
● But the near-global drought and famine of 1876-78 killed about 3.7% of the world’s population.
Note that in the 1870s world population was only about 1/6 its current 8 billion total. Yet there still wasn’t enough food for many people to eat.
The main factor contributing to the end of catastrophic famines is the extraordinary improvement in agricultural productivity. E.g., in the 1800s wheat yields in the UK were 1-2 tonnes per hectare, but now they are 8-9 tonnes per hectare.
Most of the contributors to that improvement are either directly or indirectly due to fossil fuels:
1. The manufacture of synthetic nitrogen fertilizer, mostly from natural gas, using the Haber-Bosch process (which won Fritz Haber a Nobel Prize in 1918).
2. The 47% increase in atmospheric CO2 concentration (from 289 to 425 ppmv), yielded at least a 20% global improvement in crop yields, through CO2 fertilization. Some estimates are much higher.
Agricultural studies indicate that crop yield improvement with rising CO2 levels are approximately linear to above 1000 ppmv, which is much higher than the CO2 level could ever be driven by burning recoverable fossil fuels. So, practically speaking, the higher CO2 levels go, the more our crops will benefit.
The effects of elevated CO2 have been rigorously studied, on all major crops. They all benefit. There are no exceptions. Even C4 crops like corn (maize) benefit, though less than C3 crops.
3. Rising CO2 levels improve plants’ drought resilience and water use efficiency, through reduced stomatal conductance. That is especially beneficial in drought-prone regions, like the Sahel.
Since, historically, most catastrophic famines have been caused by drought, this benefit might be the single most important contributor to the end of catastrophic
droughts(I meant to say famines).4. Agricultural mechanization is obviously heavily dependent on energy from fossil fuels, as are food processing, packaging and transportation. (Theoretically, the combination of nuclear energy and/or renewable energy, and breakthroughs in battery storage, could replace most of this application of fossil fuels, someday.)
5. Most other agricultural chemicals, such as pesticides, are made using petrochemicals, and even phosphate mining is quite energy intensive.
7. Even the production of modern high-yielding hybrid seeds depends on fossil fuels, albeit to a smaller extent than the other major contributors to improved agricultural productivity.
Most of those benefits would cease, either immediately or eventually, if Net Zero were implemented.
Both of my RealClimate comments are still hidden. Obviously the RC moderators aren’t going to allow them.
I guess censoring other viewpoints is just what you’ve got to do if your goal is to promote a false narrative. I have a list of climate blogs which don’t do that (both skeptic & alarmist), here:
https://sealevel.info/learnmore.html?0=blogs#blogs
Dave Burton:
One can point to the Medieval Warm Period, when most of the northern ice melted (farming in Greenland, etc.), so there was obviously insufficient freshwater melt to affect the Gulf Stream or the AMOC.
Otherwise, it would have turned cold.
Blocking the Denmark strait between Iceland and Greenland with glacial ice, thus stopping the 2 Km high undersea cataract that pumps the current might be the be really yuuuge event you seek….
This is hardly a helpful condemnation of the Mann et.al. hissy fit. Professor Wunsch has clearly bought in to the ‘precautionary principle’ full force and likely the whole climate doomerism movement.
Hint Professor Wunsch, even a NEW house or NEWLY wired house can have an electrical fire due to the wiring. Does that mean we should be constantly replacing the wiring? The answer is clearly no.
Professor Wunsch had an opportunity to clearly and unequivocally state what any good scientist would when presented with the statement “Amongst them, prominently, are the use of numerical models which produce ocean circulations that are far from what we actually observe. How seriously should one take their “predictions”?”
The answer is “we can not take them seriously at all”, not 1 iota of confidence should be placed in models that in his own words produce an answer “far from what we actually observe”…observation always trumps models. A good scientist would place no faith in their models for prediction and take the observed evidence as a sign that there’s something seriously wrong with the models not the planet.
No the question is how can a higher percentage of CO2 change an ocean current? We don’t even know if added CO2 can make our climate appreciably warmer. We need to worry about real world problems like affordable and reliable energy.
I think they are working really hard on problems like affordable and reliable energy. Pretty soon they’ll have totally eliminated that particular problem.
Affordable and reliable energy just won’t be available any more.
That’s true. Obviously the Biden/Harris administration worked very hard on that, as have politicians in many other western countries, but many U.S. States have also worked hard to help make energy unaffordable and unreliable.
For example, here in NC, in 2021 the NCGA enacted, with strong bipartisan support, and Gov. Cooper signed, H951, “Energy Solutions for North Carolina,” to increase the cost and reduce the reliability of electricity in North Carolina.
Of course that’s now how it was promoted, but that’s what it does. The damage is still being phased in, and it is the main reason that North Carolina’s electricity prices keep rising.
I testified against H951, to no avail. I told legislators:
Acquiescing in Green New Deal crackpottery is feeding the crocodile, in the hope it’ll eat us last. Don’t fall for it! Be Churchill, not Chamberlin! Reject this bill!
I was ignored. In the NC House the bill passed 90-to-20, and in the Senate the it was 42-to-7. Large majorities of both Democrats and Republicans voted for it.
Duke Energy lobbied hard for H951. Can you guess why?
Duke has a financial incentive to make electricity expensive. Because of cost-plus pricing, the higher their costs go, the higher their profits are. So as North Carolinians struggle to pay their escalating energy bills, Duke laughs all the way to the bank.
When H951 was under consideration the “environmentalist” Democrats in the NCGA listened to the climate industry lobbyists, the “pro-business” Republicans listened to Duke Energy’s lobbyists, and the result was a bipartisan train wreck.
It reminded me of the classic definition of “bipartisanship.” Do you know it?
– variously attributed to M. Stanton Evans, Sen. Alan Simpson, or Sen. Everett Dirksen
Help! What is the meaning of this?
Wunsch is quoted as saying:
———————
“Turning the AMOC on and off as an explanation of major past and possible future change has become a go-to-story for people who want a simple explanation of a very complicated system. … Broecker did the world a great dis-service with his advocacy of the “conveyor belt” which leads people to think they understand a system which looks nothing like his picture (a memorable graphic …). There are issues connected with the fuss over the AMOC … prominently [.] the use of numerical models which produce ocean circulations … far from what we actually observe. How seriously should one take their “predictions”? That the climate can change dramatically from what we have known for the last several hundred years is a fact, a very worrisome fact at that.”
————————
? What is this ‘fact, very worrisome’ that indicates a dramatic change from the last several centuries, encompassing an emergence from the ‘Little Ice Age’?
Seems like wishful* thinking!
— RLW
*P.S. Q. What’s in a name?
— A search yields this: Wunsch is a German word that means “to wish” or “to make a wish”
— Notable people with the surname Wunsch:
Carl Wunsch: American oceanographer born in 1941One can wish him many more happy years, but also (sadly) note that ‘science advances one funeral at a time’ [attributed to M. Planck]
post-P.S. If wishes (Wünsche) were facts, [then] alarmists would rule
I think the fact “that the climate can change dramatically” is a reference to Dansgaard-Oeschger cycles. They are, indeed, probably caused, at least in part, by AMOC changes.
But Dansgaard-Oeschger cycles don’t happen during interglacials, like our current Holocene. That’s probably because to stop or appreciably slow the AMOC would require enormous additions of freshwater to the northern North Atlantic, and without the great Laurentide & Fennoscandian ice sheets there’s no source for the required huge influxes of fresh meltwater.
The modelers don’t understand what they’re trying to model. That’s easily seen from the varying assumptions in their models. For example, CMIP6 climate models differ from one another by a factor of >3 (!!!) in their baked-in estimates of ECS climate sensitivity. If the modelers knew what they were doing that’d obviously be impossible.
It is well known from thermodynamics that temperatures cannot be averaged. If two 10 liter bodies containing air at temperatures of 30 and 40 cent degrees are merged, then the resulting temperature could be anything from approximately 31 degrees to 39 degrees depending on the humidity of air in each body. Why, then, is it interesting to take the average of samples to calculate the ESC.
As a Canadian, I say that if CO2 has warmed the earth and extended the current interglacial that is, in the vast majority, a good thing. Anybody who thinks that not extending the interglacial should be our goal, is seriously irrational. If we have been so lucky as to have increased the interglacial with greenhouse gas emissions, we have most certainly not ended the current ice age (the polar ice caps are not going anywhere, any time soon), and efforts to end any presumed interglacial extending effects of greenhouse gases are overwhelmingly antithetical to human flourishing because our civilisation will collapse entirely on the return of glaciation. But it is beyond me why anybody would believe a prophet who says that greenhouse gas emissions have warmed the earth sufficiently to extend or end the interglacial, and are also triggering the end of the AMOC which will throw Northern Europe into a disastrous cooling. Is there any claim that is too convoluted or preposterous for climate science?
Were Canadians around for the last interglacial? Was healthcare free back then?
Is there some better significance in calling it ‘multidecadal?’ Seems like a good three pages. Fisheries biologists know about it.
Enfield, D. B., A. M. Mestas-Nuñez, P. J. Trimble. 2001. The Atlantic Multidecadal Oscillation and its relation to rainfall and river flows in the continental U.S. Geophysical Research Letters. 28(10):2077-2080. https://doi.org/10.1029/2000GL012745
“AMO warm phases occurred during 1860–1880 and 1940–1960, and cool phases during 1905–1925 and 1970–1990.”
The Atlantic Multidecadal Oscillation and the Atlantic Meridional Overturning Current are two separate phenomena, operating at different time scales
Have not read the words yet but the photo…. high water _and_ ice in NYC? Aren’t those inverse?
No. Climate Change causes the worst extremes of everything, so it is both. They should have added hurricane winds as well.
The overturning just south of Greenland slows down during negative North Atlantic Oscillation episodes and regimes, while rising CO2 forcing is expected to increase positive NAO states. Obviously the latter has failed.
https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-3-5-6.html