[U-05] Advanced understanding of Quaternary and Anthropocene hydroclimate changes in East Asia

[U05-P06] Regional and global forcing of Holocene Totten Glacier retreat from deep-sea sediments perspective

*Huang Zihan^1,2, Bethany Behrens^1,2, Yosuke Miyairi¹, Takahiro AZE¹, Stephen Obrochta³, Takato Takemura⁴, Reisuke Kondo¹, Alix Post⁵, Leanne Armand⁶, Philip O'Brien⁷, Yusuke Yokoyama^1,2,8 (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.Graduate School of Arts and Sciences, The University of Tokyo, 3.Graduate School of International Resource Science, Akita University, 4.Department of Earth and Environmental Sciences, College of Humanities and Sciences, Nihon University, 5.Geoscience Australia, 6.Research School of Earth Sciences, Australian National University, 7.Department of Environment and Geography, Macquarie University, 8.Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo)

Keywords:Sea-level rise, East Antarctic Ice Sheet, Totten Glacier, beryllium isotopes, grain size, thermohaline circulation

Sea level rise is one of the greatest challenges we face in the 21^st century. How high and how soon the water rises has a lot to do with what happens in Antarctica. The East Antarctic Ice Sheet is the biggest source of potential sea level rise on Earth. If the entire ice sheet melts all at once, the global sea level will rise by about 53 m (1). Although this will not happen overnight or any time soon, a small change in the ice sheet can have large impacts all over the world. Marine-based sectors with ice grounded below sea level, such as the Totten Glacier in East Antarctica, are especially vulnerable to oceanic warming and hence sensitive to past, present, and future climate warming. An accurate reconstruction of the Totten Glacier’s past is needed to better understand the glacier’s response to present and future climate changes.
The physical, elemental, and isotopic composition of marine sediments give us hints of how the ice has reacted to past warming. We used beryllium isotope and grain size analysis to evaluate the Totten Glacier dynamics and interaction with the Southern Ocean since the Last Glacial Maximum. Our beryllium isotopes and grain size records reveal that the initial deglaciation of the Totten Glacier sector of the East Antarctic Ice Sheet started from around 17 ka, followed by rapid deglaciation from around 8.5 ka, likely due to the intrusion of warm ocean currents to the grounding line of the Totten Glacier.
It is possible that the Totten Glacier region of the East Antarctic Ice Sheet is in sync with changes in global ice volume. The synchronicity between the global ice volume and the Totten Glacier may be evidence for a teleconnection between global and Antarctic climates. Low-latitude signals such as El Niño-Southern Oscillation may have influenced Southern Hemisphere trade winds (2) via the Southern Annular Mode (3). This may have in turn influenced cyclonic activities along the Antarctic coast (4), creating upwelling that allows the intrusion of warm Circumpolar Deep Water under the ice shelf and leading to basal melting.

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