Antarctic ice sheet discharge driven by atmosphere-ocean feedbacks at the Last Glacial Termination

• Published in: Scientific Reports
• Main Authors: Fogwill, CJ, Turney, CSM, Golledge, NR, Etheridge, DM, Rubino, M, Thornton, DP, Baker, A, Woodward, J, Winter, K, van Ommen, TD, Moy, AD, Curran, MAJ, Davies, SM, Weber, ME, Bird, MI, Munksgaard, NC, Menviel, L, Rootes, CM, Ellis, B, Millman, H, Vohra, J, Rivera, A, Cooper, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2017
• Subjects: Antarctic ice sheet; Last Glacial Termination; Patriot Hills; Antarctic; Southern Ocean; The Antarctic; Weddell; Weddell Sea; Antarc*; ice core; Ice Sheet
• Online Access: https://eprints.utas.edu.au/24189/; https://eprints.utas.edu.au/24189/1/Fogwill%20et%20al%202017_Antarctic%20ice%20sheet%20discharge%20at%20LGT_NatureScReports39979.pdf; https://doi.org/10.1038/srep39979

Reconstructing the dynamic response of the Antarctic ice sheets to warming during the Last Glacial Termination (LGT; 18,000–11,650 yrs ago) allows us to disentangle ice-climate feedbacks that are key to improving future projections. Whilst the sequence of events during this period is reasonably well-known, relatively poor chronological control has precluded precise alignment of ice, atmospheric and marine records, making it difficult to assess relationships between Antarctic ice-sheet (AIS) dynamics, climate change and sea level. Here we present results from a highly-resolved ‘horizontal ice core’ from the Weddell Sea Embayment, which records millennial-scale AIS dynamics across this extensive region. Counterintuitively, we find AIS mass-loss across the full duration of the Antarctic Cold Reversal (ACR; 14,600–12,700 yrs ago), with stabilisation during the subsequent millennia of atmospheric warming. Earth-system and ice-sheet modelling suggests these contrasting trends were likely Antarctic-wide, sustained by feedbacks amplified by the delivery of Circumpolar Deep Water onto the continental shelf. Given the anti-phase relationship between inter-hemispheric climate trends across the LGT our findings demonstrate that Southern Ocean-AIS feedbacks were controlled by global atmospheric teleconnections. With increasing stratification of the Southern Ocean and intensification of mid-latitude westerly winds today, such teleconnections could amplify AIS mass loss and accelerate global sea-level rise.