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A modelling study published in Geophysical Research Letters looks at the impact of a weakened AMOC (Atlantic Meridional Overturning Circulation) on European climate.
Prof Richard Allan, Professor of Climate Science, University of Reading, said:
“Although scientists are moderately confident that the North Atlantic ocean overturning circulation will not fizzle out this century, given the dire consequences for global weather patterns it is important to test the ground for these unlikely but high impact possibilities, in the same way that we insure our homes against improbable calamity.
“Since warm upper ocean currents keep Europe milder than it would otherwise be, the simulations of an abrupt shut down in this circulation show temperatures drop like a stone in winter, while less influence in summer means hot extremes still worsen with greenhouse gas heating. Such marked winter cooling in the North Atlantic and Europe in contrast to a background of greenhouse gas warming across the rest of the world would also play havoc with wind patterns and weather systems over the continent and more widely across the globe.
“The new study is by no means the last word since it only considers one modelling centre’s simulations that may not be realistic and are not expected to play out in the real world over next few decades. But even the mere possibility of this dire storyline unfolding over coming centuries underscores the need to forensically monitor what is happening in our oceans and to continue building momentum across all sectors of society to cut greenhouse gas emissions which are driving our climate into dangerous, uncharted territory.”
Prof Jon Robson, Research Fellow at the National Centre for Atmospheric Science, University of Reading, said:
“A collapse in the strength of the AMOC would have serious implications, including for people living in Europe. This research adds to a growing worry that a collapse in the strength of the AMOC could mean sharp drops in European winter temperatures and increases in winter storminess across Northern Europe, even in a globally warming climate.
“There remains, however, a long list of questions, including whether such a collapse is likely in the real world, how quickly it could unfold, and what the precise impacts would be. It is critical that we continue to deepen our understanding of such events and their implications using all available approaches and across a range of simulations.
“Ultimately, continued greenhouse gas emissions only heightens the risks that we could unwittingly trigger such a calamity, further underlining the importance of reaching net zero.
Dr Karsten Haustein, Climate Scientist, Leipzig University, said:
“I believe their statement is a bit too assertive. I’d rather say ‘A strongly reduced AMOC state and intermediate global warming…could have a profound cooling effect on Northwestern Europe with more intense cold extremes.’
“There’s a strong north-south gradient in how much the cold extremes intensify. The UK (as well as Ireland, Iceland) and Scandinavia are most affected, with little change for countries south of the North and Baltic Sea.
“Most importantly though, it is absolutely vital to stress that warm extremes continue to increase. In other words, summer temperatures continue to go up, with heatwaves remaining or becoming the main threat linked to climate change. Accordingly, the seasonality of temperature extremes strongly increases over NW Europe, as the authors rightly point out.
“In short, the climate in NW Europe is potentially becoming more continental, with colder winter and hotter summer extremes. Not great either, but a rather different message compared to their statement.
“The study builds on existing evidence, but takes it a step further. Now greenhouse gas induced anthropogenic warming is included in the analysis, allowing to assess their balancing effect compared to scenarios without additional warming. The methods and model data are solid. Since only one climate model is used, they run two different experiments to account for the range of uncertainty (high and low freshwater flux forcing). Based on the results, it is fair to say that a collapse of the AMOC is still not a certain outcome under moderate warming conditions (RCP4.5).
“In fact, their results indicate that moderate warming might not be enough for an AMOC collapse, which – even if it does occur – does not necessarily rescue NW Europe from intensified summer heat.
Dr Alejandra Sanchez-Franks, Senior Research Scientist in Physical Oceanography, Marine Physics and Ocean Climate (MPOC), National Oceanography Centre, said:
“While these modelling studies are of great value to our community, it is important to be aware that our observational ocean records have not yet captured a tipping point, so the results of this study and their immediate impact on the real world must be interpreted with caution.”
Dr Dafydd Gwyn Evans, Senior Research Scientist in Physical Oceanography, National Oceanography Centre, said:
“This is an interesting study that provides some useful information from a theoretical point of view, but we shouldn’t use the conclusions of this study to inform us as to how the AMOC and European climate will respond to potential short term AMOC changes. The study uses an idealised experiment with unrealistic freshwater changes to force an AMOC collapse. Very importantly, the author’s conclusions refer to the European climate 200 years after an AMOC change and do not describe what will happen to European temperatures and sea-ice in the years/decades following an AMOC collapse. Therefore, the study does not serve to tell us how an AMOC tipping point / collapse will affect us immediately.”
Dr Bablu Sinha, Leader of Climate and Uncertainty, Marine Systems Modelling (MSM), National Oceanography Centre, said:
“The results are physically plausible and in line with what we know from previous modelling studies and physical reasoning. We have always expected there to be opposing effects from greenhouse warming versus AMOC shutdown but as far as I know this is the first study that tries to quantify that (suggesting that moderate greenhouse warming would not be enough to outweigh the AMOC related cooling), even though there are many caveats. The study also highlights the important influence of sea ice changes on the climate impacts.”
Dr Jenny Mecking, Research Scientist, National Oceanography Centre, said:
“Given that observational data is limited theoretical climate modelling approaches need to be taken to properly investigate this topic. Van Westen and Baatsen motivate the need for more detailed investigation into the combined impacts of global warming and AMOC decline on European extreme temperatures.”
‘European Temperature Extremes under Different AMOC Scenarios in the Community Earth System Model’ by Rene M. van Westen and Michiel L.J. Baatsen was published in Geophysical Research Letters at 2pm UK time on Wednesday 11 June 2025.
Declared interests
Richard Allan: “no conflicts of interest”
Jon Robson: “I do not have any interests to declare”
Karsten Haustein: “No conflict of interest”
For all other experts, no reply to our request for DOIs was received.