Drilling priorities to determine the past extent of the Antarctic Ice Sheet

Introduction and priority research questions

The response of the Antarctic ice sheets to warmer-than-present climates is a pressing scientific question due to its linkage to global sea level. Evidence of former cosmic-ray exposure in subglacial bedrock can reveal the dimensions of ice sheets and glaciers under warmer climate conditions in the past. Recent projects at the Pirrit Hills and the Ohio Range in Antarctica have now demonstrated the feasibility of recovering intact bedrock cores for isotope measurements, which provide strong constraints on the glacial history of the sites. As the number and geographic distribution of sites expands, this approach has the potential to constrain the history and dynamics of ice sheets under various past warmer climates. Major questions address three critical time periods: How big was the Pliocene Antarctic ice sheet? What happened to the West Antarctic Ice Sheet (WAIS) during warm and/or prolonged late Pleistocene interglacials such as Marine Isotope Stages (MIS) 5e and 11? Was the WAIS smaller than present during the late Holocene?