Early Holocene Laurentide Ice Sheet deglaciation causes cooling in the high-latitude Southern Hemisphere through oceanic teleconnection

The impact of the early Holocene Laurentide Ice Sheet (LIS) deglaciation on the climate at Southern Hemisphere high latitudes is studied in three transient simulations performed with a global climate model of the coupled atmosphere-ocean-vegetation system. Considering the LIS deglaciation, we quanti...

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Bibliographic Details
Published in:Paleoceanography
Main Authors: Renssen, H., Goosse, Hugues, Crosta, X., Roche, D. M.
Other Authors: UCL - SST/ELI/ELIC - Earth & Climate
Format: Article in Journal/Newspaper
Language:English
Published: Amer Geophysical Union 2010
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Online Access:http://hdl.handle.net/2078.1/33662
https://doi.org/10.1029/2009PA001854
Description
Summary:The impact of the early Holocene Laurentide Ice Sheet (LIS) deglaciation on the climate at Southern Hemisphere high latitudes is studied in three transient simulations performed with a global climate model of the coupled atmosphere-ocean-vegetation system. Considering the LIS deglaciation, we quantify separately the impacts of the background meltwater fluxes and the changes in topography and surface albedo. In our model, the meltwater input into the North Atlantic results in a substantial weakening of the Atlantic meridional overturning circulation, associated with absence of deep convection in the Labrador Sea. Northward ocean heat transport by the Atlantic Ocean is reduced by 28%. This weakened ocean circulation leads to cooler North Atlantic Deep Water (NADW). Upwelling of this cool NADW in the Southern Ocean results in reduced surface temperatures (by 1 degrees C to 2 degrees C) here between 9 and 7 ka compared to an experiment without LIS deglaciation. Poleward of the polar front zone, this advective teleconnection between the Southern and Northern hemispheres overwhelms the effect of the "classical" bipolar seesaw mechanism. These results provide an explanation for the relatively cold climatic conditions between 9 and 7 ka reconstructed in several proxy records from Southern Hemisphere high latitudes, such as Antarctic ice cores.