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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.

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Fig. 1: OHT as estimated through sections that separate ocean basins and delimit the tropics for the 1992–2011 time average.
Fig. 2: Meridional effective OHT.
Fig. 3: Scalar potential and vector potential as derived from the global vector field of OHT0 for the 1992–2011 time average.

Code availability

The code used to generate the results in the paper can be accessed from public repositories and permanent archives31,35. Maps shown in this paper and Supplementary Information were created using the M_map toolbox41, available at www.eoas.ubc.ca/~rich/map.html.

Data availability

The data that support the findings of this study are available from the corresponding author upon request and via the Harvard Dataverse https://doi.org/10.7910/DVN/AVVGYX. They are publicly available and permanently archived33,34.

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Acknowledgements

J. Chapin is acknowledged for helping proofread the manuscript. G.F. acknowledges support from NASA (6937342) and the Simons Foundation (549931).

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G.F. performed the analyses and wrote the manuscript. Both authors contributed to the design of the study and interpretation of the results.

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Correspondence to Gaël Forget.

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Forget, G., Ferreira, D. Global ocean heat transport dominated by heat export from the tropical Pacific. Nat. Geosci. 12, 351–354 (2019). https://doi.org/10.1038/s41561-019-0333-7

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