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Southern Ocean temperature records and ice-sheet models demonstrate rapid Antarctic ice sheet retreat under low atmospheric CO2 during Marine Isotope Stage 31

Abstract : We quantify precisely the magnitude of ocean warming using the first ever Southern Ocean molecular paleo-temperature reconstructions during the warm Marine Isotope Stage 31 (MIS31-1.085 and 1.055 million years ago). Our data show a sustained surface Southern Ocean warming and a collapse of the Antarctic and sub Antarctic ocean fronts during that warm period and under low atmospheric CO 2 concentrations. We use sea surface temperature reconstructions to test the scenarios for the AIS retreat during MIS31 using coupled ice-sheet/ice-shelf model. We propose a two-step model for deglaciating West Antarctica which involves mild ocean warming (a new temperature threshold) which forces ice margin 29 retreat followed by rapid ocean warming as the ice sheet retreats.Our work shows that the Paris Agreement target temperature of 1.5°C is sufficient to drive runaway retreat of the West Antarctic Ice Sheet. We derive this conclusion from the robust, ocean temperature proxy record and ice sheet simulation.
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Submitted on : Friday, November 29, 2019 - 12:35:15 AM
Last modification on : Thursday, July 9, 2020 - 3:39:22 AM

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Catherine Beltran, Nicholas R. Golledge, Christian Ohneiser, Douglas E. Kowalewskie, Marie-Alexandrine Sicre, et al.. Southern Ocean temperature records and ice-sheet models demonstrate rapid Antarctic ice sheet retreat under low atmospheric CO2 during Marine Isotope Stage 31. Quaternary Science Reviews, Elsevier, 2020, 228, ⟨10.1016/j.quascirev.2019.106069⟩. ⟨insu-02385673⟩

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