East Antarctic meltwater influx from the Wilkes Subglacial Basin since the Last Glacial Maximum as determined by beryllium isotopes

Behrens, Bethany1,2, Miyairi, Yosuke1, Sproson, Adam D.1, Yamane, Masako3, Yokoyama, Yusuke1,2,4

1Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Japan 2Graduate Program on Environmental Science, University of Tokyo, Komaba, Japan 3Institute for Space-Earth Environmental Research, Nagoya University, Furocho, Japan 4Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, Hongo, Japan

The West Antarctic Ice Sheet (WAIS) and East Antarctic Ice Sheet (EAIS) contain an amount of ice equivalent to 3-5 m and 53 m sea level rise, respectively (1). The WAIS, as a largely marine-based ice sheet, is susceptible to changes in ocean temperatures and prone to retreat. Recent research has revealed that areas of the EAIS situated below sea level are also very sensitive to atmospheric and oceanic temperature changes and vulnerable to retreat (2, 3). The two largest subglacial basins in East Antarctica, the Wilkes and Aurora basins, hold a total ice mass equivalent to 28 m sea level rise (4), demonstrating that even a partial collapse of the EAIS would have a major effect on global sea level.

While we know the general timing of post-LGM glacial retreat around Antarctica, there is scarce data on specific locations with detailed, high-resolution records of ice sheet dynamics during the Holocene. Here we present meteoric beryllium-10 (10Be) analysis of a marine sediment core from the Adélie Basin, located on the continental shelf offshore the Wilkes Basin, extracted during IODP Expedition 318. Our record covers the most recent period of major Holocene ice sheet retreat, sea level rise, and increased atmospheric CO2 since the Last Glacial Maximum ice sheet retreat (5). The beryllium isotope data suggest oceanic or climatic changes occurred at ca. 9.8 ka, ca. 6.3 ka, and from ca. 4.1 ka. From prior research, we can conclude our high meteoric 10Be values at ~9.8 ka and ~6.3 ka are attributed to an open marine environment created by the retreat of grounded ice along with an increased influx of meltwater (6-8). The elevated concentration and frequency variation of meteoric 10Be values starting from ~4.1 ka indicate a change in regime, possibly linked to changes in climate.

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(8) Behrens B, Miyairi Y, Sproson AD, Yamane M, Yokoyama Y. Journal of Quaternary Science. 2019;34(8):603-8.


Biography

Bethany is a PhD candidate at the Atmosphere and Ocean Research Institute, the University of Tokyo where she is analyzing beryllium isotope ratios of marine sediment cores extracted from the Southern Ocean and lake sediment cores from Tasmania to better understand ice sheet dynamics between glacial and interglacial periods.

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