Global ocean heat transport dominated by heat export from the tropical Pacific

Abstract

Heat redistribution is one of the main mechanisms by which oceans regulate Earth’s climate. Analyses of ocean heat transport tend to emphasize global-scale seawater pathways and concepts such as the great ocean conveyor belt. However, it is the divergence or convergence of heat transport within an oceanic region, rather than the origin or destination of seawater transiting through that region, that is most immediately relevant to Earth’s heat budget. Here we use a recent gridded estimate of ocean heat transport to reveal the net effect on Earth’s heat budget, the ‘effective’ ocean heat transport, by removing internal ocean heat loops that have obscured the interpretation of measurements. The result demonstrates the overwhelming predominance of the tropical Pacific, which exports four times as much heat as is imported in the Atlantic and Arctic. It also highlights the unique ability of the Atlantic and Indian oceans to transport heat across the Equator—Northward and Southward, respectively. However, effective inter-ocean heat transports are smaller than expected, suggesting that global-scale seawater pathways play only a minor role in Earth’s heat budget. Effective heat transport in the global ocean is dominated by heat export from the tropical Pacific, whereas seawater transport pathways play only a minor role, according to an analysis of a gridded ocean data product.