Atmosphere Ocean Science Colloquium

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The impacts of Indian Ocean warming on the Atlantic: from the meridional overturning to the warming hole

Speaker: Shineng Hu, Columbia

Location: Warren Weaver Hall 1302

Date: Wednesday, February 12, 2020, 3:30 p.m.

Synopsis:

The tropical Indian Ocean (TIO) has warmed progressively by 1°C since the 1950s and will probably continue to warm as the atmospheric carbon dioxide level keeps rising. In this talk, I will discuss how the TIO warming could influence global climate via interacting with the Atlantic Ocean, which has been largely overlooked before. For the fast response, the TIO warming could strengthen the surface westerly winds over the subpolar North Atlantic and therefore cool the underlying ocean within a few months to years. This mechanism could potentially explain the suppressed warming trend in the subpolar North Atlantic (i.e. the so-called "warming hole") during the historical warming period. For the slow response, the TIO warming could increase the tropical Atlantic salinity via rainfall reduction and thus strengthen the Atlantic meridional overturning circulation (AMOC) after several decades. The resultant AMOC strengthening then leads to a warmer global mean surface temperature, a stronger hemispheric asymmetry, and a northward shifted intertropical convergence zone (ITCZ). Implications for past and future climate changes will be discussed.