Ka-Kit Tung presents "Varying planetary heat sink led to global-warming slowdown and acceleration"

At the 2014 MCRN Annual Meeting, Ka-Kit Tung (MCRN node-leader at the University of Washington) presented "Varying planetary heat sink led to global-warming slowdown and acceleration," explaining the 15-year hiatus in increasing global temperatures. This had been a mystery that has generated many theories among climate scientists. K.K. reviewed the theories and explained the problems in each one. Data from 3500 Argo floats covering the earth's oceans revealed that the Atlantic Ocean is saltier than the Pacific. K.K. explained how it is the salinity of the Atlantic that is responsible for the periodic warming of the deeper Atlantic water rather than the surface air, thus explaining why global temperatures did not increase during the hiatus.

This is work Ka-Kit Tung and Xianyao Chen (University of Washington and Ocean University of China) published in Science 22, August 2014: Vol. 345 no. 6199 pp. 897-903, DOI: 10.1126/science.1254937

Abstract: A vacillating global heat sink at intermediate ocean depths is associated with different climate regimes of surface warming under anthropogenic forcing: The latter part of the 20th century saw rapid global warming as more heat stayed near the surface. In the 21st century, surface warming slowed as more heat moved into deeper oceans. In situ and reanalyzed data are used to trace the pathways of ocean heat uptake. In addition to the shallow La Niña–like patterns in the Pacific that were the previous focus, we found that the slowdown is mainly caused by heat transported to deeper layers in the Atlantic and the Southern oceans, initiated by a recurrent salinity anomaly in the subpolar North Atlantic. Cooling periods associated with the latter deeper heat-sequestration mechanism historically lasted 20 to 35 years.

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Ka-Kit Tung at the 2014 MCRN Annual Meeting


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