| Summary: | Although it is also affected by the deep-water temperature, as a first order approximation, the oxygen isotopic composition (δ18O) of the deep-sea sediments is often assumed to represent the global ice volume variation. The δ18O records of the deep-sea cores show significantly reduced amplitude of the global ice volume variations before about 450 ka ago, with less warm (cooler) interglacials and generally less cold glacials. The most glaciated interglacials MIS-13 (about 500 ka ago) during the last one million years is recorded in most of the δ18O records. At the same time, exceptional climate events have been found during this interglacial over the whole world. In particular, the extremely strong (the strongest over the last one million years) East Asian, Indian and Africa monsoon occurring during this cooler (coldest) interglacial is very surprising, because ice sheets are generally assumed to weakens the monsoon through cooling the continents. To test the impact of the ice sheets on the MIS-13 climate in particular the monsoon, we have made sensitivity experiments with the following possibilities: 1. Assuming the Greenland and Antarctica ice sheets keep their present-day volume, we analyze the response of the model to different Eurasian and North America ice sheets volumes, from the biggest 11.9, 24.2 106 km3 respectively to 0. 2. A transient experiments, where no Eurasian and North American ice sheet, using the interactive Greenland and Antarctica ice sheets model under the MIS-13 insolation and greenhouse gases forcings. 3. Many evidences show that it is a high probability that actually the ice volume signal of MIS-13 is mainly due to the Southern Hemisphere ice sheets. We therefore analyze the response of the climate to a ice sheets condition where the Greenland ice sheet is smaller and the Antarctica ice sheet is bigger than today.
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