Mid-Holocene Antarctic sea-ice increase driven by marine ice sheet retreat

• Published in: Climate of the Past
• Main Authors: Ashley, Kate, McKay, Robert, Etourneau, Johan, Jimenez-Espejo, Francisco, Condron, Alan, Albot, Anna, Crosta, Xavier, Riesselman, Christina, Seki, Osamu, Massé, Guillaume, Golledge, Nicholas, Gasson, Edward, Lowry, Daniel, Barrand, Nicholas, Johnson, Katelyn, Bertler, Nancy, Escutia, Carlota, Dunbar, Robert, Bendle, James
• Other Authors: UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Antarctic; East Antarctica; The Antarctic; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves; Sea ice
• Online Access: https://hal.archives-ouvertes.fr/hal-03102309; https://hal.archives-ouvertes.fr/hal-03102309/document; https://hal.archives-ouvertes.fr/hal-03102309/file/Ashley_CP2020.pdf; https://doi.org/10.5194/cp-17-1-2021

International audience Over recent decades Antarctic sea-ice extent has increased, alongside widespread ice shelf thinning and freshening of waters along the Antarctic margin. In contrast, Earth system models generally simulate a decrease in sea ice. Circulation of water masses beneath large-cavity ice shelves is not included in current Earth System models and may be a driver of this phenomena. We examine a Holocene sediment core off East Antarctica that records the Neoglacial transition, the last major baseline shift of Antarctic sea ice, and part of a late-Holocene global cooling trend. We provide a multiproxy record of Holocene glacial meltwater input, sediment transport, and sea-ice variability. Our record, supported by high-resolution ocean modelling, shows that a rapid Antarctic sea-ice increase during the mid-Holocene (∼ 4.5 ka) occurred against a backdrop of increasing glacial meltwater input and gradual climate warming. We suggest that mid-Holocene ice shelf cavity expansion led to cooling of surface waters and sea-ice growth that slowed basal ice shelf melting. Incorporating this feedback mechanism into global climate models will be important for future projections of Antarctic changes.