Thursday, 5 October - 11:30 - EARTH SYSTEM PHYSICS SEMINAR

[Earth System Physics Section]

EARTH SYSTEM PHYSICS SEMINAR
Thursday, 5 October - 11:30 hrs
Central area, 2nd floor, ex-SISSA bldg.

"Can Arctic sea ice decline weaken the Atlantic meridional overturning 
circulation?"

Alexey Fedorov
Professor of Oceanic and Atmospheric Sciences
Dept. of Geology and Geophysics
Yale University

The ongoing decline of Arctic sea ice exposes the ocean to anomalous 
surface heat and
freshwater fluxes, resulting in positive buoyancy anomalies that can 
affect ocean
circulation. In this study, we use an optimal flux perturbation 
framework and
comprehensive climate model simulations to estimate the sensitivity of 
the Atlantic
meridional overturning circulation (AMOC) to such buoyancy forcing over 
the Arctic and
globally, and more generally to sea ice decline. It is found that while 
on decadal
timescales flux anomalies over the subpolar North Atlantic have the 
largest impact on
the AMOC, on multi-decadal timescales (longer than 20 years) flux 
anomalies in the
Arctic become more important. These positive buoyancy anomalies spread 
to the North
Atlantic, weakening the AMOC and its poleward heat transport. Therefore, 
the Arctic
sea ice decline may explain the suggested slow-down of the AMOC and the 
“Warming Hole”
persisting in the subpolar North Atlantic.



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