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

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 117; no. 8; pp. 3996 - 4006
• Main Authors: 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, Zoe 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, Cooper, Alan
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 25-02-2020
• Series: PNAS Plus
• Subjects: Deoxyribonucleic acid; Destabilization; DNA; Environmental changes; Glaciers; Hydrates; Ice; Ice sheets; Methane hydrates; Microorganisms; Mountains; Ocean models; Ocean temperature; Ocean warming; Physical Sciences; PNAS Plus; Polar environments; Sea level; Sea level changes; Sheet modelling; Thermal expansion; Water circulation; Antarctica; Weddell Sea; Southern Ocean; Antarctic ice sheets; marine ice sheet instability (MISI); polar amplification; tipping element; paleoclimatology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1902469117

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 (~2 m), ocean thermal expansion, and melting mountain glaciers (~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 theWeddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by majormethane hydrate reserves. Constrained by awidespread 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.