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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Preprints
https://doi.org/10.5194/tc-2020-112
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-2020-112
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

  25 May 2020

25 May 2020

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A revised version of this preprint is currently under review for the journal TC.

Sensitivity of the Antarctic ice sheets to the peak warming of Marine Isotope Stage 11

Martim Mas e Braga1,2, Jorge Bernales3, Matthias Prange3, Arjen P. Stroeven1,2, and Irina Rogozhina3,4 Martim Mas e Braga et al.
  • 1Geomorphology & Glaciology, Department of Physical Geography, Stockholm University, Stockholm, Sweden
  • 2Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
  • 3MARUM - Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
  • 4Department of Geography, Norwegian University of Science and Technology, Trondheim, Norway

Abstract. Studying the response of the Antarctic ice sheets to past climate conditions similar to the present day can provide important insights for understanding its current changes and help identify natural drivers of ice sheet retreat. The Marine Isotope Substage 11c (MIS11c) interglacial is one of the best candidates for an in-depth analysis given that at its later portion orbital parameters were close to our current interglacial. However, Antarctic ice core data indicate that although MIS11c CO2 levels were close to Pre Industrial, warmer-than-present temperatures (of about 2 °C) lasted for much longer than during other interglacials. Since the global mean sea level is thought to have been 6‐13 m higher than today, there should have been some contribution from Antarctica. While substantial work has been conducted regarding the response of the Greenland Ice Sheet to the MIS11c climate, which is believed to have contributed with 3.9–7.0 m to global sea level, both configurations of the Antarctic ice sheets and their contribution to sea level rise remain poorly constrained. We use a numerical ice-sheet model to shed light on the response of the Antarctic ice sheets to MIS11c climate conditions obtained from a combination of a suite of Antarctic ice cores and the LR04 global stack of deep-sea sediment records and climate model outputs, while assessing the model sensitivity to the uncertainties in sea level reconstructions, ice sheet initial configuration, and multi-centennial climate variability. We found that the regional climate signal of the MIS11c peak warming in Antarctica captured by the ice core records is necessary for the recorded sea level highstand to be reproduced, and that warming length was more important than magnitude. However, there is a threshold for a West Antarctic Ice Sheet collapse that lies within an envelope of 1.6 and 2.1 °C warmer-than-pre-industrial regional climate conditions. Sea level forcing and multi-centennial variability were found to have played virtually no role in driving ice sheet contraction, but the choice of initial configuration of the East Antarctic Ice Sheet provided a large source of uncertainty in the quantification of MIS11c Antarctic peak sea level contribution, which falls between 6.4 and 8.8 m.

Martim Mas e Braga et al.

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Martim Mas e Braga et al.

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Latest update: 03 Dec 2020
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Short summary
We combine a computer model with different climate records to simulate how Antarctica responded to warming during Marine Isotope Stage 11c, which we know little about and can provide important information to understand Antarctica’s natural drivers of change. We found that the regional climate warming of Antarctica seen in the ice cores was necessary for the model to match the recorded sea level rise, contributing with 6.4 to 8.8 m, and that the warming duration was more important than the peak.
We combine a computer model with different climate records to simulate how Antarctica responded...
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