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
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Planète et Univers [physics]/Sciences de la Terre/Climatologie; Planète et Univers [physics]/Sciences de la Terre/Océanographie; Planète et Univers [physics]/Océan; Atmosphère; Antarctic; The Antarctic; East Antarctica; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves; Sea ice
• Online Access: https://oskar-bordeaux.fr/handle/20.500.12278/188612; https://hdl.handle.net/20.500.12278/188612; https://doi.org/10.5194/cp-17-1-2021

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.