Impact of melt water on high latitude early Last Interglacial climate

Recent data compilations of the early Last Interglacial period have indicated a bipolar temperature response at 130 ka, with colder-than-present temperatures in the North Atlantic and warmer-than-present temperatures in the Southern Ocean and over Antarctica. However, climate model simulations of this period have been unable to reproduce this response, when only orbital and greenhouse gas forcings are considered in a climate model framework. Here we show using full complexity General Circulation Model simulations at 130 ka with the magnitude of freshwater forcing derived from data, that meltwater from the remnant Northern Hemisphere ice-sheets during the glacial-interglacial transition accounts for the observed colder than present temperatures in the North Atlantic at 130 ka and also results in warmer than present temperatures in the Southern Ocean via the bipolar seesaw mechanism. This integrated model-data approach, for the first time, provides evidence that Northern Hemisphere freshwater forcing is an important player in the evolution of early Last Interglacial climate.

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