Atmosphere Ocean Science Colloquium

Changes in ocean water masses reveal excess heat in the climate system

Speaker: Jan Zika, U. New South Wales

Location: Warren Weaver Hall 1314

Date: Friday, January 31, 2020, 4 p.m.


Accounting for 93% of the excess heat in the earth system, ocean warming is central to understanding climate change. The recent Argo observing program has revealed regional patterns of warming and cooling up to ten times the global average. So the regional distribution of excess heat is being obscured by large and compensating regional patterns of change. Regional ocean heat content changes occur either through the addition of excess heat at the ocean surface or through redistribution within the ocean of existing water masses. Here we present a novel diagnosis of the ‘excess’ and ‘redistributed’ contributions to regional heat content change between 2006 and 2017 based on water mass theory. A planetary scale southward redistribution of up to 0.1PW explains broad heat content changes in the Southern Ocean and North Atlantic.  Meanwhile 0.4±0.08PW of excess heat is concentrating in tropical and subtropical regions with the largest reservoir in the North Atlantic.