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The role of an Arctic ice shelf in the climate of the MIS 6 glacial maximum (140 ka)

Abstract : During the last decade, Arctic icebreaker and nuclear submarine expeditions have revealed large-scale Pleistocene glacial erosion on the Lomonosov Ridge, Chukchi Borderland and along the Northern Alaskan margin indicating that the glacial Arctic Ocean hosted large Antarctic-style ice shelves. Dating of sediment cores indicates that the most extensive and deepest ice grounding occurred during Marine Isotope Stage (MIS) 6. The precise extents of Pleistocene ice shelves in the Arctic Ocean are unknown but seem comparable to present existing Antarctic ice shelves. How would an Antarctic-style ice shelf in the MIS 6 Arctic Ocean influence the Northern Hemisphere climate? Could it have impacted on the surface mass balance (SMB) of the MIS 6 Eurasian ice sheet and contributed to its large southward extent? We use an Atmospheric General Circulation Model (AGCM) to investigate the climatic impacts of both a limited MIS 6 ice shelf covering portions of the Canada Basin and a fully ice shelf covered Arctic Ocean. The AGCM results show that both ice shelves cause a temperature cooling of about 3 °C over the Arctic Ocean mainly due to the combined effect of ice elevation and isolation from the underlying ocean heat fluxes stopping the snow cover from melting during summer. The calculated SMB of the ice shelves are positive. The ice front horizontal velocity of the Canada Basin ice shelf is estimated to ≈ 1 km yr−1 which is comparable to the recent measurements of the Ross ice shelf, Antarctica. The existence of a large continuous ice shelf covering the entire Arctic Ocean would imply a mean annual velocity of icebergs of ≈12 km yr−1 through the Fram Strait. Our modeling results show that both ice shelf configurations could be viable under the MIS 6 climatic conditions. However, the cooling caused by these ice shelves only affects the Arctic margins of the continental ice sheets and is not strong enough to significantly influence the surface mass balance of the entire MIS 6 Eurasian ice sheet.
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Submitted on : Friday, December 16, 2011 - 4:05:33 PM
Last modification on : Friday, September 25, 2020 - 9:16:03 AM

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F. Colleoni, G. Krinner, M. Jakobsson. The role of an Arctic ice shelf in the climate of the MIS 6 glacial maximum (140 ka). Quaternary Science Reviews, Elsevier, 2010, 29 (25-26), pp.3590-3597. ⟨10.1016/j.quascirev.2010.06.023⟩. ⟨insu-00652954⟩

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