Séminaire
Dansgaard-Oeschger (D-O) cycles are the most dramatic, frequent, and wide-reaching abrupt climate changes in the geologic record. On Greenland, D-O cycles are characterized by an abrupt warming of 10±5°C from a cold stadial to a warm interstadial phase, followed by gradual cooling before a rapid return to stadial conditions. The mechanisms responsible for these millennial cycles are not fully understood. Here, we investigate three different mechanisms whether or not they induce a D-O event. These mechanisms are i) increasing the Southern Ocean winds, ii) strengthen the North Atlantic Subpolar Gyre iii) a warm pool anomaly in western Equatorial Pacific Ocean. We employ a fully coupled (atmosphere-ocean-land-seaice) climate model for the MIS3 climate. The results show that Southern Ocean can change the Atlantic Overturning Circulation and induce a D-O event in 150 years.
Julie.Deshayes@locean-ipsl.upmc.fr