East Antartic ice sheet and ocean interactions during past warmer than present climates

The recently published Sixth Assessment Report by the Intergovernmental Panel on Climate Change identified the Antarctica's contribution to sea-level change as the single greatest uncertainty in global climate predictions for the coming decades and centuries, and the highest priority issue facing climate change science. Observations show that ice sheets grounded on land below current sea level (marine-based ice sheets) are vulnerable to ocean-induced basal melting, resulting in destabilization and sea level rise. However, the exact mechanisms that drive oceanic heat exchange across the continental shelves, and their influence on the stability of the marine-based ice sheets are poorly known. High-resolution records of past ice sheet and ocean circulation interaction can fill this gap. Of particular use is the study of past warmer-than-present climate intervals, when temperatures and CO2 concentrations were similar to the present-day or those projected for the end of this century. The ICEAN project will deliver a unique shelf to open ocean transect of geological records on water masses, ocean temperature, and ice sheet position for the Mid-Pliocene warm period (~3 million years ago). Back then, atmospheric CO2 concentrations where similar to the present-day (ca. 400ppm), and mean annual surface temperatures were ca. 1.8-3.6C warmer than preindustrial values. These conditions led to reduced ice sheet extent and increased sea levels. The data produced in the ICEAN project will for the first time allow to constrain processes and drivers for ice retreat during the Mid-Pliocene warm period in a critical location off East Antarctica. The results will be key to validate and test current ice sheet models, which are used to project future seal level rise.