Atlantic Meridional Overturning Circulation Collapse
Recent research indicates that the collapse of the Atlantic Meridional Overturning Circulation (AMOC) could lead to extreme winter temperatures in northern Europe. This study, led by Dr René van Westen from Utrecht University, was published in June 2025. It marks the potential consequences of climate change and freshwater influx from melting ice sheets.
About AMOC
The AMOC is a critical ocean current system. It transports warm water from the tropics to northern latitudes and returns cold water southward. This process regulates climate by distributing heat. Disruption of the AMOC could lead to changes in temperature patterns across Europe.
Impact of Freshwater Influx
Human-induced climate change is increasing freshwater levels in the North Atlantic. The melting of Greenland’s ice sheet adds freshwater, reducing seawater salinity and density. This disrupts the sinking process essential for the AMOC’s functioning.
Climate Modelling Approach
The study used the Community Earth System Model (CESM) to simulate an AMOC collapse. Researchers applied a strong freshwater forcing to the North Atlantic. This approach helped to address biases in climate models that previously suggested the AMOC was more stable than observed.
Projected Climate Consequences
The simulations revealed stark outcomes. Under a scenario of 2 degrees Celsius warming, winter temperatures in London could drop to an average of 1.9°C, with extreme lows approaching -19.3°C. In Edinburgh, temperatures could reach -29.7°C. Oslo may experience average winter temperatures of -16.5°C, with lows near -48°C.
Seasonal Temperature Variability
While winter temperatures could plummet, summer conditions might remain warmer than pre-industrial levels. This could create dramatic seasonal contrasts, leading to intense heatwaves in summer. The climate would shift from extreme cold in winter to extreme heat in summer.
Broader Implications Beyond Europe
The study suggests that an AMOC shutdown could also impact global weather patterns. It could shift the Intertropical Convergence Zone southward. This shift may weaken monsoon systems in regions like India, West Africa, and the Amazon, altering rainfall patterns.
Societal and Infrastructural Challenges
The potential for extreme cold poses challenges. Current societal structures and infrastructures in Europe are not designed to withstand such severe winter conditions. This raises concerns about preparedness for extreme weather events in a warming world.
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