Abstract

Several lines of geological evidence from both the marine and terrestrial record tell us that the Antarctic Ice Sheet was much bigger than present at the Last Glacial Maximum. Determining how it has changed in both thickness and extent since then, in particular whether it has undergone any major fluctuations in the last few thousand years, is important for validating ice sheet and glacial-isostatic adjustment models that are used to project future sea level rise.

In this talk, I will present an overview of the emerging evidence for large-scale reversible retreat of the Antarctic Ice Sheet during the mid to late Holocene period. I will discuss the methods with which we can further investigate this phenomenon and present a case study from the Amundsen Sea sector illustrating how cosmogenic nuclide measurements in subglacial bedrock reveal regrowth of the Pine Island-Thwaites Glacier system from a smaller than present configuration in the Holocene. Direct evidence for reversible retreat from this and other locations in Antarctica is urgently needed in order to understand what drives regrowth of ice sheets in warm climates and the conditions under which ongoing retreat could be reversed.