A new study published in Geophysical Research Letters warns that a collapse of the Atlantic Meridional Overturning Circulation (AMOC) could drastically alter Europe’s climate, triggering extreme cold winters in northern Europe even as the planet continues to warm. The research investigates how AMOC collapse interacts with global warming under various scenarios and highlights the potential for Europe to become significantly colder—particularly in winter—due to disrupted ocean heat transport and expanded sea ice.
AMOC is a major system of Atlantic ocean currents that transports warm tropical waters northward and cold water southward. It plays a vital role in regulating climate, particularly in Europe. Scientists are increasingly concerned that human-driven climate change is weakening the AMOC, possibly pushing it toward an irreversible “tipping point.”
Using the Community Earth System Model (CESM), the researchers simulated scenarios where AMOC remains stable, and where it collapses, under varying degrees of global warming. The study focuses on long-term projections—several centuries into the future—after the climate has stabilized into a “new normal” following an AMOC collapse.
In a 2°C warmer world (aligned with the RCP4.5 emissions pathway), an AMOC shutdown could result in profoundly colder winters across Europe. London could see one-in-ten-year winter cold extremes of nearly -20°C, while Oslo could experience temperatures plunging to -48°C. These frigid conditions stem from the breakdown of oceanic heat transport and the spread of Arctic sea ice to the coasts of northwestern Europe, significantly cooling the region despite ongoing global warming.
This effect is not merely additive; the study finds a “super-additive” relationship—meaning the combined effects of warming and AMOC collapse result in more severe climate impacts than either would cause alone. While summer temperatures in affected regions would still be warmer than in pre-industrial times, the seasonal contrast would dramatically increase. This could lead to intense heatwaves in summer and severe cold snaps in winter—what researchers describe as a climate of extremes.
The study also examines what would happen in a more extreme scenario where the world warms by 4°C. In this case, global warming would dominate, and northern Europe would still warm overall, though less than the global average. The region would not experience the same level of sea ice expansion or winter cooling as in the 2°C scenario.
Importantly, the researchers emphasize that their model does not predict when the AMOC might collapse, only what the long-term effects would be if it did. Their simulations rely on artificially large freshwater inputs to trigger collapse—necessary due to the overly stable AMOC behavior in most climate models. Despite this simplification, the study offers valuable insights into the risks of compound climate impacts.
Experts unaffiliated with the study praise its contribution, noting that few modern studies have examined the interaction between AMOC collapse and global warming in such detail. However, they also caution that the findings do not reflect near-term risks but rather far-future possibilities, and should not be misinterpreted as short-term forecasts.
The authors argue that policymakers should take these findings seriously. Europe’s infrastructure is not built to withstand Arctic-like winters, and planning must account for low-probability, high-impact events such as an AMOC shutdown. The study reinforces the need to invest in ocean monitoring and improve models to reduce uncertainty around tipping points in the climate system.
Source: CarbonBrief
Website: Ocean current ‘collapse’ could trigger ‘profound cooling’ in northern Europe – even with global warming - Carbon Brief
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