Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica

Turney, Chris S. M., Fogwill, Christopher J., Golledge, Nicholas R., Mckay, Nicholas P., van Sebille, Erik, Jones, Richard T., Etheridge, David, Rubino, Mauro, Thornton, David P., Davies, Siwan M., Ramsey, Christopher Bronk, Thomas, Zoë A., Bird, Michael I., Munksgaard, Niels C., Kohno, Mika, Woodward, John, Winter, Kate, Weyrich, Laura S., Rootes, Camilla M., Millman, Helen, Albert, Paul G., Rivera, Andres, van Ommen, Tas, Curran, Mark, Moy, Andrew, Rahmstorf, Stefan, Kawamura, Kenji, Hillenbrand, Claus-Dieter, Weber, Michael E., Manning, Christina J., Young, Jennifer, and Cooper, Alan (2020) Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica. Proceedings of the National Academy of Sciences of the United States of America, 117 (8). pp. 3996-4006.

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Abstract

The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level cannot be fully explained by Greenland Ice Sheet melt (similar to 2 m), ocean thermal expansion, and melting mountain glaciers (similar to 1 m), suggesting substantial Antarctic mass loss was initiated by warming of Southern Ocean waters, resulting from a weakening Atlantic meridional overturning circulation in response to North Atlantic surface freshening. Here, we report a blue-ice record of ice sheet and environmental change from the Weddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by major methane hydrate reserves. Constrained by a widespread volcanic horizon and supported by ancient microbial DNA analyses, we provide evidence for substantial mass loss across the Weddell Sea Embayment during the LIG, most likely driven by ocean warming and associated with destabilization of subglacial hydrates. Ice sheet modeling supports this interpretation and suggests that millennial-scale warming of the Southern Ocean could have triggered a multimeter rise in global sea levels. Our data indicate that Antarctica is highly vulnerable to projected increases in ocean temperatures and may drive ice-climate feedbacks that further amplify warming.

Item ID: 62625
Item Type: Article (Research - C1)
ISSN: 1091-6490
Keywords: Antarctic ice sheets, marine ice sheet instability (MISI), paleoclimatology, polar amplification, tipping element
Copyright Information: Copyright © 2020 the Author(s). Published by PNAS. This Open Access article is distributed under Creative Commons Attribution License 4.0 (CC BY).
Funders: Australian Research Council (ARC), Royal Society of New Zealand (RSNZ), Antarctic Logistics and Expeditions, Natural Environment Research Council (UK) (NERC), Coleg Cymraeg Cenedlaethol, European Research Council (ERC), Fulbright Commission, Japanese Society for the Promotion of Science (JSPS), Ministry of Education, Science, Sport and Culture, Japan
Projects and Grants: ARC FL140100044, ARC LP120200724, NERC NE/1027576/1, Fulbright (259253 and FP7/2007-2013), Japanese government Grant-in-Aid for Scientific Research (15KK0027 and 17H06320)
Date Deposited: 25 Mar 2020 07:35
FoR Codes: 04 EARTH SCIENCES > 0402 Geochemistry > 040203 Isotope Geochemistry @ 20%
04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040605 Palaeoclimatology @ 40%
04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040602 Glaciology @ 40%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960303 Climate Change Models @ 20%
96 ENVIRONMENT > 9603 Climate and Climate Change > 960306 Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) @ 50%
97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 30%
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