[M-IS03] The Southern Ocean and the Antarctic Ice Sheet dynamics in past, present and future

[MIS03-P03] Antarctic slope current intensification following Last Glacial Maximum ice retreat

*Bethany C. Behrens^1,2, Yusuke Yokoyama^1,2,3, Yosuke Miyairi¹, Alexandra L Post⁴, Leanne K Armand^5,10, Stephen P Obrochta⁶, Naohiko Ohkouchi⁷, Hisami Suga⁷, Takato Takemura⁸, Philip E O'Brien⁹ (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.Graduate Program on Environmental Science, The University of Tokyo, 3.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 4.Geoscience Australia, Australia, 5.Research School of Earth Sciences, Australian National University, 6.Akita University Graduate School of International Resource Science, Japan, 7.Japan Agency for Marine-Earth Science and Technology, Japan, 8.Geomechanics Lab, College of Humanities and Sciences, Nihon University, 9.Department of Environmental Sciences, Macquarie University, Australia, 10.Deceased, Leanne Kay Armand on 4 January 2022)

Keywords:Southern Ocean, Antarctic Slope Current, Sabrina Coast, Beryllium isotopes, Totten Glacier

The Antarctic Ice Sheet holds an amount of ice equivalent to ~58 m sea level rise, with the East Antarctic Ice Sheet containing 90 % of that ice (~53 m sea level rise) (1). The smaller West Antarctic Ice Sheet, with 3 to 5 m sea level rise equivalent of ice, is a marine-based ice sheet, more susceptible to changes in ocean temperatures and sea level than ice sheets on bedrock above sea level. Recent research has revealed that areas of the East Antarctic Ice Sheet situated below sea level are also sensitive to sea level and oceanic temperature changes and vulnerable to retreat (1, 2). The two largest subglacial basins in East Antarctica, the Wilkes and Aurora basins, hold a total ice mass equivalent of 3 to 4 m (3) and 3.5 m sea level rise equivalent of ice (4, 5), respectively, demonstrating that even a partial collapse of the East Antarctic Ice Sheet would have a major effect on global sea level.

Totten Glacier is one of the largest outlet glaciers of East Antarctica and a major outlet glacier of the Aurora Basin in Wilkes Land (6). The deep, landward-sloping bed of the Totten Glacier makes it particularly vulnerable to retreat (7). Here we present grain size and reactive beryllium-10 and beryllium-9 ratio (¹⁰Be/⁹Be_reac) analysis of a marine sediment core extracted from the continental rise of the Sabrina Coast region, East Antarctica to evaluate the influence of climatic changes from the Last Glacial Maximum through the Holocene on Totten Glacier dynamics and changes in current strength to identify driving mechanisms of glacial retreat in this region. Our results suggest initiation of oceanic or climatic changes leading to increased current strength and enhanced ice sheet retreat following the Last Glacial Maximum from ca. 17 ka BP and ca. 8 ka BP.

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