
The collapse of a key Atlantic Ocean current system could plunge winter temperatures across northern Europe to unprecedented lows, even in a world warmed by greenhouse gas emissions.
That was the conclusion of a major climate modelling study led by Dr René van Westen and colleagues at Utrecht University, published in the journal Geophysical Research Letters on June 11, 2025. The research explored what could happen if the Atlantic Meridional Overturning Circulation (AMOC) — a vital component of Earth’s climate system — were to shut down entirely in the future.
The AMOC forms part of a larger network of ocean currents that transports warm surface water northwards from the tropics and returns cold, dense water southward along the ocean floor. It helped regulate temperatures across Europe and other regions by shifting heat from equatorial to higher latitudes.
Scientists warned that human-induced climate change, particularly the melting of Greenland’s ice sheet, had been adding large amounts of freshwater to the North Atlantic. This influx reduced the salinity and density of seawater, disrupting the sinking process that drove the AMOC.
Instead of focusing on whether a full collapse may occur, the study simulated the long-term climate consequences under different warming scenarios if such a tipping point were crossed.
To model an AMOC collapse, van Westen and his team used the Community Earth System Model (CESM) and applied a strong freshwater “forcing” to the North Atlantic. This extreme scenario allowed them to bypass a known bias in climate models that made the AMOC appear more stable than observations suggested. The simulations projected conditions hundreds of years after a shutdown, assuming the climate had reached a new equilibrium.
The results were stark. Under an intermediate emissions scenario where global warming stabilised at 2 degrees Celsius above pre-industrial levels — a shutdown of the AMOC caused profound cooling in parts of Europe.
In London, average winter temperatures fell to 1.9°C, with cold extremes approaching -19.3°C once every decade. In Edinburgh, one-in-ten-year lows reached -29.7°C. Oslo saw average winter temperatures of -16.5°C, with extreme lows near -48°C. In such a scenario, winter sea ice extended to the coasts of Great Britain and Scandinavia, amplifying the regional cooling.
While summer temperatures remained slightly cooler than today’s levels, they still rose well above pre-industrial conditions—leading to dramatic seasonal swings. “The extreme winters would be like living in an ice age,” Tim Lenton, a climate scientist at the University of Exeter, who was not involved in the study, was quoted in an article by climate science website Carbon Brief. “But at the same time summer temperature extremes are barely impacted… It would be like coming out of the freezer into a frying pan of summer heatwaves.”
The study showed that under a higher emissions pathway, where warming exceeded 4°C by 2100, the cooling from an AMOC collapse would no longer offset global heating. Northern Europe would still warm, albeit more slowly and without significant sea ice advance.
Van Westen told Carbon Brief the most striking result was that Europe could become colder in a world that was otherwise warmer. “Parts of the Netherlands and the UK will experience spectacular cold extremes down to -20°C or even lower,” he said. “Our societal structure and infrastructure is not built for these cold extremes.”
The research also highlighted potential changes beyond Europe. A shutdown of the AMOC could shift the Intertropical Convergence Zone southwards, weakening monsoon systems across India, West Africa and the Amazon and altering rainfall patterns in the tropics.
The research underscored the risk that Europe could become an outlier in the climate crisis, cooling in winter even as the planet heated overall.