Modeled sensitivity of the Fennoscandian Ice Sheet to paleoclimate forcings using PISM-PIK

Abstract:

The history of past ice sheets, such as the Fennoscandian Ice Sheet (FIS), provides examples of how ice-sheets and ice-shelves interacted during past variations in climate. These examples may inform predictions of the impact of ongoing climate change for present ice sheets. A crucial first step to quantitatively model the collapse of the Fennoscandian Ice sheet is to assess the sensitivity of the modeled ice sheet to paleoclimate. PISM-PIK, a coupled ice sheet and ice shelf model, is used to simulate the extent, thickness, and movement of the Fennoscandian Ice Sheet at the LGM. I modeled last glacial maximum (LGM) climate using PMIP3 GCM and compared the ice sheet geometry that results from holding climate fixed at PMIP3 LGM conditions to the observed extent of the FIS at LGM. This same procedure was completed for a modern climate scaled to LGM conditions. I then explored the impact on modeled ice sheet extent of spatially-uniform perturbations in temperature and precipitation for both LGM climates. The goal is to assess the stability of the ice sheet –ice shelf system to changes in fundamental aspect of climate (precipitation and temperature) individually and in concert. The misfit between the modeled extent of the FIS and the geomorphic record of this extent will be used to assess possible errors in paleoclimate models and representations of ice dynamics.