Department Seminar: Wei Liu

Title: Climate impacts of a weakened Atlantic Meridional Overturning Circulation

Abstract: While the Atlantic Meridional Overturning Circulation (AMOC) is projected to slow down under anthropogenic warming, the exact role of the AMOC in future climate change has not been fully quantified. By maintaining AMOC intensity in anthropogenic warming experiments, we isolate and quantify the AMOC climatic impact in a coupled climate system. We find that a weakened AMOC leads to surface cooling south of Greenland and a reduced Arctic sea ice loss in all seasons with a delay of about 6 years in the emergence of an ice-free Arctic in boreal summer. The AMOC slowdown can also diminish the annual mean Arctic warming by 2 °C by the end of the century, which primarily results from surface albedo feedback and changes in ocean heat uptake. These two factors are inextricably linked on seasonal timescales, and their relative importance for Arctic amplification can vary by season.