Session: Warm Climates (Mid-Holocene, Last interglacial, Deep-time, Pliocene)
Author: Louise Sime / lsim@bas.ac.uk / British Antarctic Survey
Co-author: Jochen Voss, University of Leeds;
                    Dario Domingo, University of Leeds;
                    Max Holloway, British Antarctic Survey;
                    Irene Malmierca, British Antarctic Survey;

Abstract:
Far-field sea level records have provided evidence that parts of the Antarctic Ice Sheet and Greenland ice sheet were likely lost during the Last Interglacial (LIG) period, 116-129 thousand years ago. Reconstructing ice sheet changes within the LIG however remains a difficult problem. Sediment cores from beneath the West Antarctic Ice Sheet (WAIS) support the view that parts were lost within the last 1.3 million years (e.g. Scherer et al., 1998), but again the timing of the loss is unknown. And set against this, proximal ice-rafted debris evidence from marine sediment cores has been interpreted to suggest that there was no major loss of the WAIS in the last 250,000 years (e.g. O’Cofaigh et al., 2001) or last 1.8 million years (Hillenbrand et al., 2002). Near field marine and sub-ice sheet sediment core data has not provided conclusive evidence of LIG changes in the WAIS, or the wider Antarctic or Greenland ice sheets. The resultant lack of agreement and knowledge about the ice sheet changes, particularly the WAIS, during the LIG hampers our ability to calibrate models of potential ice sheet loss in the future. Ice cores provide amongst the best dated proximal evidence of LIG change across the Antarctica and Greenland (e.g. Masson-Delmotte et al., 2011; Capron et al., 2014), it is therefore very helpful if we can use ice core measurements to provide constraints on the rate and timing of ice sheet change throughout the LIG. Holloway et al. (2016) thus explored the ice core signal of WAIS change; we found that ice sheet meltwater and/or ice sheet morphology changes would be recorded in Antarctic and Greenland ice cores. Here we present our recent progress on reconstructing ice sheet changes, simulating how possible LIG ice sheet and sea ice changes would be imprinted on Antarctic and Greenland ice cores using isotopically enabled climate model simulations of the LIG. We present initial results from a novel statistical approach to this problem, using isotopic model output emulation, to test the interplay of ice sheet, meltwater, and sea ice changes on the ice core record.