Southern Ocean temperature records and ice-sheet models demonstrate rapid Antarctic ice sheet retreat under low atmospheric CO 2 during Marine Isotope Stage 31

• Published in: Quaternary Science Reviews
• Main Authors: Beltran, Catherine, Golledge, Nicholas R., Ohneiser, Christian, Kowalewskie, Douglas E., Sicre, Marie-Alexandrine, Hagemang, Kimberly J., Smith, Robert, Wilson, Gary S., Mainié, François
• Other Authors: University of Otago Dunedin, Nouvelle-Zélande, Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), Worcester State University Worcester, Variabilité de l'Océan et de la Glace de mer (VOG), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), LEFE/IMAGO 2013
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDV]Life Sciences [q-bio]; [SDU]Sciences of the Universe [physics]; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Antarctic; Antarctic Ocean; Southern Ocean; The Antarctic; West Antarctic Ice Sheet; West Antarctica; Antarc*; Antarctica; Ice Sheet; Ice Shelf
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-02385673; https://hal-insu.archives-ouvertes.fr/insu-02385673/document; https://hal-insu.archives-ouvertes.fr/insu-02385673/file/Beltran%20et%20al-pre-print.pdf; https://doi.org/10.1016/j.quascirev.2019.106069

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.