Session: Glacial Climates (LGM, Last deglaciation, Ice sheet uncertainties, Glacial-interglacial cycles)
Author: Matthias Prange / email@example.com / MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany
Co-author: Irina Rogozhina, MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany;
André Paul, MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany;
Pepijn Bakker, MARUM - Center for Marine Environmental Sciences, University of Bremen, Germany;
Julien Seguinot, Laboratory of Hydraulics, Hydrology and Glaciology, ETH Zürich, Switzerland;
Jorge Bernales, GFZ German Research Centre for Geosciences, Helmholtz Centre Potsdam, Germany;
The British-Irish Ice Sheet of the last glacial was situated in a region that is critically sensitive to the poleward oceanic heat transport in the Atlantic. We employ the results of two Last Glacial Maximum (LGM) global climate simulations by the Community Climate System Model (CCSM) versions 3 and 4 at about 1° resolution in both the ocean and the atmosphere. The simulated North Atlantic sea-surface conditions are compared to temperature reconstructions by the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) project, while the atmospheric model output is used to force an ice-sheet model of the northern hemisphere. The results show that a reduced northward ocean heat transport associated with a weakened AMOC in the glacial CCSM3 simulation is consistent with extensive ice-sheet cover over the British-Irish Isles as inferred from independent geological evidence for the LGM. By contrast, a strong AMOC in the glacial CCSM4 simulation results in North Atlantic surface temperatures that are several degrees warmer than the MARGO reconstructions. As a consequence, the advection of relatively warm air from the North Atlantic towards Europe prevents the formation of a British-Irish Ice Sheet in the corresponding ice-sheet simulation. We suggest that ice-sheet modelling provides a powerful tool to evaluate paleoclimate model simulations within the framework of PMIP4.