Greenland melt is a leading driver: added freshwater is less dense than salty water, making it harder for the AMOC’s northward flow to sink and complete the circulation that redistributes Atlantic heat.
For the United States, the clearest near-term concern is the East Coast, where a circulation slowdown was estimated in a 2025 study to explain 20% to 50% of the rise in Northeast coastal flood days since 2005.
Other research and the IPCC’s 2021 assessment also tie a weaker AMOC to shifts in Atlantic rainfall, storm tracks and broader weather patterns that could reach eastern North America, though regional US impacts remain uncertain.
This report explores how the Atlantic Meridional Overturning Circulation (AMOC) moves heat from the tropics northward, shaping global and regional climates. It explains that changes in the AMOC, influenced by factors like the North Atlantic Oscillation and ocean heat transport, can reshape environmental conditions across the North Atlantic. The weakening of the AMOC, shown by both models and sea surface temperature data, leads to regional sea level changes and could trigger more extreme weather, especially along US coasts. Understanding these connections is crucial for predicting future climate impacts and preparing effective responses.