East Antarctic Ice Sheet sensitivity under vulnerable conditions studied by combination of focused geophysical techniques

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The long-standing paradigm that the East Antarctic Ice Sheet (EAIS) remains relatively stable, while only the marine-based West Antarctic Ice Sheet is vulnerable to the currently progressing climate change, has been challenged. The East Antarctic Ice Sheet around Denman Glacier in the Davis Sea sector of the southern Indian Ocean has recently been identified as potentially vulnerable to incursions of warm deep water. This is highly relevant for future climate and sea-level projections, because the potential ice mass loss of the Denman Glacier and connecting ice masses in its catchment hinterland would contribute to a sea-level rise of up to 1.5 to 2 m. Records of its behavior during past warm periods will provide constraints on this vulnerability. One of the basic data knowledge required for an assessment of past EAIS behavior is a mapping and analysis of the glacial-marine sediments on the continental shelf and rise as they represent archives of past ice sheet dynamics. Comprehensive shallow sub-surface hydroacoustic and high-resolution seismic to deep-basin seismic surveys on the continental shelf offshore Denman and neighboring outlet glaciers, to be acquired during RV Polarstern expedition PS141 in early 2024, will provide the key data of this project. The reconstructed seismic stratigraphy, linked to ocean drilling sites for chronostratigraphic control, will contain pattern of glacially transported sediments from erosion to deposition and, thus, enable a quantification of periods of major ice sheet advances and retreats. The combination of the different seismic recording setups will allow to image glacial structures at different depth at optimal resolution. In addition, the basement structures imaged by deep-basin seismics reveal tectonic lineaments and faults as well as former ice sheet grounding pinning points indicating possible extents of rift basins acting later as pathways for ice streams. The main work will be carried out by two PhD students, one at Kiel University and the other one at AWI, who will work very close together as the different hydroacoustic and seismic data sets complement each other. The reconstruction of glacial dynamics, in particular in past warm times, e.g. the Oligocene, Mid-Miocene, Pliocene warm periods as well as the last interglacials and retreat from the Last Glacial Maximum, will be used to feed the parameterization of paleo-ice sheet modelling simulations. The goal is to reveal the vulnerability of the East Antarctic Ice Sheet in warm periods in comparison to observations and models for the West Antarctic Ice Sheet. The results of this project will help lift the projections of the future behaviour of the East Antarctic Ice Sheet to a new level.