| Summary: | The climate predicted to occur over the next centuries by the Intergovernmental Panel on Climate Change appears to be unprecedented over the last 150 years. This requests therefore to go back in the past history of the Earth looking for analogues. As we are presently in an interglacial (the Holocene), the interglacials of the late Pleistocene are particularly well suited. This is why we have investigated the response of the climate system to insolation and CO2 at the peaks of the interglacials over the past 800,000 years using models of different complexity. These simulations show that the relative contributions of insolation and CO2 to the intensity and duration of each interglacial vary from one interglacial to another. They also show that CO2 plays a dominant role on the variations of the global annual mean temperature and of the southern high latitude temperature and sea ice, whereas, insolation plays a dominant role on the variations of monsoon precipitation, vegetation and of the northern high latitude temperature and sea ice. In the explanation of the warmer climate during the interglacials after about 430,000 years ago than those before, boreal winter is found to be a key season, a phenomenon similar to the present-day global warming. If we identify the peaks of the interglacials with Northern Hemisphere summer occurring at perihelion, MIS-1, MIS-11 and MIS-19 (respectively 12, 409 and 788 thousands of years ago - ka) show a pretty similar latitudinal and seasonal distribution of the incoming solar radiation (insolation). When compared to the average of the last 9 interglacials, they are under-insolated over the whole globe during boreal summer and are over-insolated during boreal winter with a maximum at the South Pole. This insolation distribution leads to a cooling over all the continents in boreal summer and to a warming over the whole Earth, except the Arctic, in boreal winter. A warming over the Southern Ocean in austral winter occurs during MIS-1 and MIS-19 due to the summer remnant effect of ...
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