Simulation of the transition between Mid Miocene Climate Optimum (17-15 Ma) and Miocene Climate Transition (14 Ma)

Mid Miocene Climate Optimum (MMCO) is an interesting period. Indeed since Mid Eocene (40 Ma) the large trends of climate evolution are: a large decrease of pCO2 and a drastic cooling. The MMCO appears as a short period when these trends were reversed, during 2 Ma, followed by a new period of cooling. Using the IPSL CM5A2 coupled model, we simulated the MMCO using two different pCO2 values (2.5 PAL and 1.5 PAL) and for the Miocene Climate Transition MCT for which we used a pCO2 value of 1.5 PAL. Superimposed to these very long runs we further simulated sensitivity of these experiments to insolation at the top of the atmosphere for Antarctica ice-sheet. In our referent simulation, the astronomical parameters remained unchanged as present day, whereas we performed new simulations with maximum and minimum insolation at the top of the atmosphere for December, January, February (at 75°S). These series of experiments will be analyzed and compared with available data. Moreover, we will compare our results to other simulations using various OAGCMs. We will emphasize on the consistency between the climate simulated at high latitude and the prescribed ice-sheet reconstruction of Antarctica.