Antarctic Ice Sheet Response to Past Warmer than Present climates

ended

The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), identified the future evolution of the Antarctic Ice Sheet, particularly of its portions grounded on land that is below current sea level (marine-based), as one of the most dramatic unknowns in global climate predictions, severely hampering reliable estimations of sea-level rise for coming decades and centuries. Our objective is to study geological records of past deglaciations to understand the processes, rates and drivers of marine-based East Antarctic Ice Sheet (EAIS) loss. Because our climate is evolving to global atmospheric CO2 concentrations higher than 400 ppm (already higher than during Mid-Pliocene Warm Period in average), we propose to study two end-members: the last deglaciation (Holocene), and two Pliocene deglaciations taking place under a range of climatic and oceanic conditions. With this innovative approach, we can better understand the processes, rates and drivers of marine-based EAIS loss under warmer than present climates, their contribution to global sea level rise, and to assess their biological impacts. We will use strategically located paleoclimate records collected in a depth transect (continental shelf-to-rise sediment cores) from the East Antarctic Wilkes Land margin during the Integrated Ocean Drilling Program Expedition 318. In addition to the work proposed for this project, we benefit from an exceptional pool of unpublished and published geological material from these cores, which will allow us to conduct a high-resolution multiproxy study of the proposed glacial terminations in the timeframe of this project. Boundary conditions from these records will be key to validate and test current ice sheet models, which at present are highly parametrised and critically need observations (e.g. melt rates, ocean conditions and circulation, freshwater flux and stratification).