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

• Published in: Scientific Reports
• Main Authors: Fogwill, C., Turney, C., Golledge, N., Etheridge, D., Rubino, M., Thornton, D., Baker, A., Woodward, J., Winter, K., Van Ommen, T., Moy, A., Curran, M., Davies, S., Weber, M., Bird, M., Munksgaard, N., Menviel, L., Rootes, C., Ellis, B., Millman, H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2017
• Subjects: Antarctic; Southern Ocean; The Antarctic; Weddell Sea; Weddell; Antarc*; ice core; Ice Sheet
• Online Access: http://hdl.handle.net/2440/103934; 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. C.J. Fogwill . & A. Cooper