Recent research indicates the AMOC has been stable for the last 40-60 years, and paleo data takes that further back.
New modeling by Baker et al. shows that Atlantic circulation is hard to change. The researchers simulated a sudden 4x increase in carbon dioxide levels and let the models run for a century. They write that “it [the AMOC] does not collapse in the model experiments considered here.”
That depends on how you define stable. The paper says
a few global climate models suggest that the AMOC could collapse (that is, weaken to zero or reverse)
So they equate “collapse” with weaken to zero. The models show AMOC weakening, but no complete collapse. Would you say your income is stable if it drops in half but doesn’t go to zero?
The conclusion that there wasn’t a complete collapse in the past and there wont be one in the future isn’t really good news. Paleo data shows that AMOC changes in the past had large climate impacts. If future weakening is like past weakening, we can expect future climate impacts to also have large impacts. Good news would be a collapse in the past but not in the future. Unfortunately, that’s not what they’re saying.
The authors conclude
The future extent of AMOC decline remains uncertain despite its critical impact on heat, carbon and nutrient transport and thus on global climate and ecosystems.
Here’s their graph of model AMOC weakening. Each curve is a different climate model. None go to zero and the authors conclude there will be no complete collapse. Roughly, the models show AMOC weakening by about half.
Consensus is not proof. The scientific method tests hypothesis against reality. All consensus says is that many think the hypothesis is valid while few doubt it. That’s not proof. I love the way Richard Feynman started one of his lectures, “You start with a guess. All it is is a guess.”
Some parts of Europe might see temperatures plunge by up to 30 degrees Celsius over a century, the study finds,
“might see temperatures plunge” is not proof, it’s a hypothesis, a guess. This hypothesis suggests that global warming with rearrange temperatures, some higher, some lower.
Stefan Rahmstorf, a physical oceanographer at Potsdam University in Germany, who was not involved with the study, said it was “a major advance in AMOC stability science.”
I was thinking of the Volkov paper that came out in September:
Florida Current transport observations reveal four decades of steady state https://www.nature.com/articles/s41467-024-51879-5 The results of this study indicate that, if climate models are correct that the AMOC is slowing or will soon slow down, this slowdown has not yet been reflected in the FC [Florida Current] and the AMOC transports, or the observational records [since 1982] are still too short to detect it with confidence. This is in accord with other observation-based studies.
Absolutely. If you want proof go to math. The square root of 2 is irrational, prime numbers go on forever, the Pythagorean theorem. All rigorously proven.
Science is not math. Science gives evidence, not proof. If the evidence is strong you get consensus. There’s no proof that apples fall from trees, the Sun will rise tomorrow, microbes cause disease, smoking causes cancer, or humans are changing the climate. It’s all evidence and consensus.
Atlantification drives recent strengthening of the Arctic overturning circulation
Arthun et al. https://www.science.org/doi/10.1126/sciadv.adu1794
Abstract:
The Arctic Ocean is the northern terminus of the Atlantic Meridional Overturning Circulation (AMOC), whose dense water masses are key to the global ocean circulation. The Arctic climate is rapidly changing, and it is not known how the Arctic Ocean overturning circulation is responding.
Here, we use a high-resolution ocean reanalysis, corroborated by observations, to show that a poleward expansion of warm Atlantic waters and corresponding sea-ice loss, a phenomenon referred to as an “Atlantification” of the Arctic, has caused a poleward shift of the dense water source regions in recent decades (1993–2020).
This is manifested in enhanced surface water mass transformation in the Arctic Ocean, compensating for a reduction in the Nordic Seas. The associated strengthening of the Arctic Ocean overturning circulation has ensured that the transport of dense overflow waters across the Greenland-Scotland Ridge to the AMOC’s lower limb has remained stable. Our results thus provide evidence for a resilient northern overturning circulation in a warming climate.
What you acknowledge by posting this paper is that climate change is causing major changes in ocean currents and the global distribution of hot and cold ocean water in real time. It is all happening now. It is not hypothetical. We just don’t know what the consequences will be.
Perhaps it will work out in our favor. Perhaps it won’t. The point though is that we are unnecessarily rolling the climate dice and crossing our fingers.
My feeling is that we would be better off not taking the gamble. But then I’ve never been a big fan of russian roulette.
And what we do know from measurements (as noted upthread) is that there has been 4+ decades of steady state. Some computer studies pick that up, others haven’t, so don’t put too much faith in computer simulations/projections.
This is demonstrably false. In about 2015 a phenomenon called the cold blob was reported in the North Atlantic. This is an area near Greenland that shows significant cooling in water temperature. Further study indicates that the blob be detected in historical records about 10 years prior, indicating at least two decades of persistence. This means it represents a some large shift in ocean behavior.
In summary, we observe an actual, unexpected and persistent physical anomaly in the North Atlantic–unusually cold water temp in an area called the "North Atlantic Warming Hole. It can be detected by direct measurements of the water and by satellite imagery so there is no dispute over its existence. The only explanation that can simulate the cold blob using multiple climate models is a slowing AMOC.
…the Atlantic overturning slowdown causes an oceanic heat transport divergence across the subpolar North Atlantic, which, while partially offset by enhanced ocean heat uptake, results in cooling over the warming hole region.
Another independent study was published this month (June 2025) using different methods that support the AMOC weakening conclusion as the explanation of the cold blob. https://www.science.org/doi/10.1126/sciadv.ads1624
A weakened AMOC is also associated with colder, drier lower atmospheric conditions, which lead to a reduction in surface warming expected from increasing amounts of heat-trapping gases by reducing downward clear-sky longwave radiation at the surface. This radiative pathway and the oceanic processes contribute equally to the North Atlantic cold blob. These results highlight the importance of the AMOC’s impact on atmospheric properties and their radiative effects.
I’m not sure we’re talking about the same “this”. I was referring to:
Florida Current transport observations reveal four decades of steady state https://www.nature.com/articles/s41467-024-51879-5 The results of this study indicate that, if climate models are correct that the AMOC is slowing or will soon slow down, this slowdown has not yet been reflected in the FC [Florida Current] and the AMOC transports…
So, we have a steady current, and the AMOC is apparently also supported by ‘Atlantification’.
You claim “there has been 4+ decades of steady state.” The Arctic Ocean undergoing “Atlantification” and the appearance of the “Cold Blob” that is best explained by a slowing AMOC are clear evidence that this is not true. The oceans are in a state of flux. The oceans are changing due to climate change. And every day we find something new and unexpected about those changes.
It is only odd if one is looking at this research through the lens of ideology rather than critical reasoning.
Technology changes. Measurements taken by different methods/equipment are difficult to compare. This is particularly true when the measurements are of something that shows high variability and the differences looked for are small.
Here is a methods paragraph from your 40 year Florida current paper you linked:
To analyze the long-term change in the Florida Current (FC) strength, we use the ~40-year (1982–2023) records of (i) the daily estimates of the FC volume transport inferred from voltages measured on submarine telecommunication cables between Florida and Grand Bahama Island and (ii) the snapshot transport estimates based on direct in situ measurements at the 27°N section. In addition, we use (iii) the transport estimates inferred from cross-stream sea surface height (SSH) differences measured by satellite altimetry in 1992–2023.
Note that three different methods were used to measure water transport. The first is an indirect measure based on voltage differences from telecom cables. The authors note that this is subject to error “The cable recording system is subject to hardware problems that result in data gaps and often in spurious drifts and offsets in the recorded voltages.”
They try to adjust for this by using periodic direct measurements from ships. They spend a lot of time discussing how this recalibration was done. One can make one’s own judgement as to how successful they were but it is worth recognizing that the measurements reported and used in the analysis were highly processed. Not saying they are wrong, I’m just questioning whether there is sufficient precision in their highly processed data to be able to see relatively small changes in a highly variable system.
