Holocene Ice Shelf Collapse and Subsequent Antarctic Ice Sheet Retreat in Lützow-Holm Bay, East Antarctica, Driven by Warm Deep Water Inflow and Sea Level Rise

Recent observations and model simulations show that the inflow of warm Circumpolar Deep Water (CDW) causes rapid and significant melting and thinning of the ice shelves of the West Antarctic Ice Sheet, contributing to the ongoing increase in the discharge of grounded ice. This process is also thought to contribute to the deglaciation of the West Antarctic Ice Sheet after the Last Glacial Maximum (LGM). However, the role of the CDW in a potential large-scale ice-mass loss in East Antarctica is largely unknown. In this study, we present new, well-dated sedimentary core records of the ice sheet and ice shelf retreat since the LGM, including a signature of the ice shelf collapse in Lützow-Holm Bay (LHB), eastern Dronning Maud Land, East Antarctica. Foraminiferal C-14 ages indicate the ice shelf collapses occurred at ca. 9 ka, which is consistent with the initiation of the thinning of the East Antarctic Ice Sheet revealed by Be-10 surface exposure dating along the southern coast of the bay. In addition, foraminiferal carbon isotope data from the cores suggest that the CDW inflow had intensified and reached the southern coast during this period. Using a hierarchical modelling approach that combines climate and high-resolution ocean simulations, we find that freshwater discharge from adjacent sectors of the AIS into the Southern Ocean likely enhanced regional CDW inflow into submarine troughs in the LHB between 10 and 9 ka. Our results suggest that a series of cascading tipping points propagated around the Antarctic margin during the last glacial termination, highlighting the importance of feedbacks between meltwater input, CDW intrusion onto the continental shelf, ice shelf stability and ice sheet dynamics, and relative sea level rise for both historical and future changes in the AIS.