The URL address of the model description of ECHAM3 is http://www.dkrz.de/forschu ng/reports-eng.html Report No. 6 ECHAM3-Atmospheric General Circulation Model. Intention of the ECHAM3_T42_7000Xanom-experiments: Geological evidence points to a global Younger Dryas (YD) climatic oscillation during the last glacial/present interglacial transition phase. A convincing mechanism to explain this global YD climatic oscillation is not yet available. The Hamburg atmospheric circulation model was used to perform four numerical experiments on the YD climate. The following boundary conditions were altered: sea surface conditions, ice sheets, insolation, atmospheric CO2 concentration. Special features of this experiment (ECHAM3_T42_70005anom): This experiment was made with an global SST set derived from 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.