Session: Glacial Climates (LGM, Last deglaciation, Ice sheet uncertainties, Glacial-interglacial cycles)
Author: Pepijn Bakker / firstname.lastname@example.org / MARUM, University of Bremen, Germany
Co-author: Matthias Prange, MARUM, University of Bremen, Germany;
Irina Rogozhina, MARUM, University of Bremen, Germany;
The elevation of the Last Glacial Maximum (LGM) ice sheets that covered large parts of North America and Eurasia is uncertain. This is reflected in the PMIP4 LGM protocol through the option to use either the ICE-6G or GLAC-1D ice sheet reconstructions. Previous work has shown that the climate is especially sensitive to changes in the elevation of the Laurentide Ice Sheet, with possible impacts on the strength of the Atlantic Meridional Overturning Circulation, and temperatures over the North Atlantic, northeastern Asia and the North Pacific. Here we use the CESM1.2 coupled atmosphere (CAM5 at 2°-resolution), ocean (POP2 at 1°-resolution) and sea-ice (CICE4 at 1°-resolution) general circulation model. Firstly, we force LGM simulations with these two different ice sheet reconstructions to test the sensitivity of the LGM climate to the uncertainty in the PMIP4 ice sheet boundary conditions and analyze the underlying mechanisms. Subsequently we use the simulated climate states to force an ice sheet model, which allows us to evaluate the paleoclimate simulations in terms of their consistency with the imposed boundary conditions and with the reconstructed ice-sheet extents.