Speaker : Florence Colleoni, CMCC Bologna
According to geological evidence, for the Northern Hemisphere, the last two glacial cycles ended with different ice sheet distributions at the last two glacial maxima (~140 kyrs BP and ~21 kyrs BP). Indeed, at 140 kyrs BP, the Eurasian ice sheet was bigger than at the Last Glacial Maximum (21 kyrs BP). This implies that the Laurentide ice sheet could have been smaller at 140 kyrs BP than at 21 kyrs BP, under the assumption of an equal sea-level drop during the two glacial maxima. It could be that this difference in ice distribution started at the glacial inception or that it was generated at some point during the glacial cycle. To address this question, we use a coupled atmosphere-ocean general circulation model and a stand-alone thermodynamics ice sheet model to simulate the evolution of climate and ice distribution over the last two glacial inceptions spanning [125 -115] kyrs BP (MIS 5) and [236 – 229] kyrs BP (MIS 7), respectively. Taking into account only orbital and greenhouse gases variations, the results show that at the beginning of MIS 7, external forcing led to conditions that were more favorable for the growth of the Eurasian ice sheet than during MIS 5. These results indicate that a reversed Northern Hemisphere ice distribution between the last two cycles is a realistic hypothesis. However, these simulations do not account for ice-albedo and elevation feedbacks. To confirm our
results, coupled climate-ice sheets simulations are needed.
CMCC Bologna - CMCC Bologna -
29 Jun 2012
Division Organized by
- CMCC - Euro-Mediterranean Center on Climate Change
- INGV - Istituto Nazionale di Geofisica e Vulcanologia