Interbasin and interhemispheric impacts of a collapsed Atlantic Overturning Circulation

Climate projections suggest a weakening or collapse of the Atlantic Meridional Overturning Circulation (AMOC) under global warming, with evidence that a slowdown is already underway. This could have significant ramifications for Atlantic Ocean heat transport, Arctic sea ice extent and regional North Atlantic climate. However, the potential for far-reaching effects, such as teleconnections to adjacent basins and into the Southern Hemisphere, remains unclear. Here, using a global climate model we show that AMOC collapse can accelerate the Pacific trade winds and Walker circulation by leaving an excess of heat in the tropical South Atlantic. This tropical warming drives anomalous atmospheric convection, resulting in enhanced subsidence over the east Pacific and a strengthened Walker circulation and trade winds. Further teleconnections include weakening of the Indian and South Atlantic subtropical highs and deepening of the Amundsen Sea Low. These findings have important implications for understanding the global climate response to ongoing greenhouse gas increases.