This experiment was made with changed SSTs in the N-Atlantik, lowered SST's in the N-Pacific, but with additional ice sheets, insolation, CO2 lowered and some land points added. A winter SST set in the N-Atlantic is redefined, based on the coupled AGCM-OGCM experiments described in Schiller et al., 1996, MPI report 188. The global response to these boundary conditions was analysed using three variables: surface temperature, zonal wind speed, precipitation. The statistical significance of the changes was tested with a two tailed t-test. Moreover, the significant responses to cooled oceans were compared with geological evidence of a YD oscillation. This comparison revealed a good match in Europe, Greenland, Atlantic Canada and the North Pacific region, explaining the YD oscillation in these regions as a response to cooled N-Atlantic an N-Pacific Oceans. However, the results leave the YD climate in other regions completely unexplained. This reflects either an insufficient set of boundary conditions or the important role played by feedbacks within the coupled atmosphere-ocean-ice system. These feedbacks are poorly represented in the used atmospheric model, since ice sheets and the ocean surface conditions have to be prescribed.