New research suggests the Atlantic current, which makes European winters milder, might be nearing a tipping point. This finding comes from advanced climate models that simulated a complete collapse of this vital system.
The Atlantic Meridional Overturning Circulation (AMOC) works like a giant conveyor belt, moving warm water from the tropics to the North Atlantic. There, it cools, sinks, and returns south. This process affects weather patterns and rainfall far beyond the Atlantic, including regions like the Amazon and West Africa.
If the AMOC weakens significantly, northern Europe could experience much colder winters, even as global temperatures rise. Additionally, some coastal areas could see higher sea levels than the global average.
In the Utrecht University study, researchers used the Community Earth System Model to investigate the AMOC. They gradually added fresh water to the North Atlantic over 1,700 simulated years. This added fresh water makes surface water less salty and less dense, which disrupts the sinking process and can lead to a collapse.
Initially, the model showed a gradual weakening of the AMOC. Then, it abruptly failed. The northward movement of heat in the Atlantic dropped by 75%, cooling western European waters by up to 10 degrees Celsius. Arctic sea ice expanded southward, and temperatures in several European cities plunged by 5 to 15 degrees within a century. This rapid shift would drastically change what people consider a “normal winter.”
To monitor early warning signs, researchers focused on how the AMOC exchanges fresh and salty water near 34 degrees south. They noticed clear trends: as the system became unstable, the exchange pattern became more negative. About 25 years before the predicted collapse, the data showed a defined minimum, acting as a physical warning signal. Historical data supports this trend, revealing a similar negative shift over the past 40 years, suggesting the current AMOC is approaching a tipping point.
While the study does not specify when a real collapse might occur, it emphasizes the importance of addressing greenhouse gas emissions and monitoring ocean currents. The findings highlight a strong link between the AMOC’s stability and emissions levels. Cutting emissions could mitigate the influx of fresh water into the North Atlantic. Moreover, expanding ocean observing systems will be crucial for scientists to spot early warning signs as they happen.
For more information on the research, you can view the full study in Science Advances.
