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

• Published in: Climate of the Past
• Main Authors: K. E. Ashley, R. McKay, J. Etourneau, F. J. Jimenez-Espejo, A. Condron, A. Albot, X. Crosta, C. Riesselman, O. Seki, G. Massé, N. R. Golledge, E. Gasson, D. P. Lowry, N. E. Barrand, K. Johnson, N. Bertler, C. Escutia, R. Dunbar, J. A. Bendle
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Environmental pollution; TD172-193.5; Environmental protection; TD169-171.8; Environmental sciences; GE1-350; Antarctic; East Antarctica; The Antarctic; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves; Sea ice
• Online Access: https://doi.org/10.5194/cp-17-1-2021; https://doaj.org/article/b3d220c787124d858c4429a93e335953

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 multi-proxy 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.