Global reorganization of atmospheric circulation during Dansgaard-Oschger cycles

Ice core records from Greenland evidence abrupt warming event recurring at millennial time scales during previous glacial intervals. Although transitions strongly resembling these Dansgaard-Oeschger (DO) transitions have been revealed in several speleothem records, our understanding of the climate and ecosystem impacts of the Greenland warming events in lower latitudes remains incomplete. Here, we investigate the influence of these transitions on the global atmospheric circulation pattern. We comprehensively analyse d18O changes during DO transitions in a globally distributed dataset of speleothems. The speleothem d18O signals mostly represent changes in precipitation amounts and moisture source, and thereby allows us to infer spatially resolved changes in global atmospheric dynamics that are characteristically linked to the DO transitions. In addition to the previously proposed shift of the Intertropical Convergence Zone towards more northerly positions, we find evidence for a similar northward shift of the westerly winds of the northern Hemisphere. Furthermore, we reveal a decreasing trend of the transition amplitudes with increasing distance from the North Atlantic region, justifying earlier assumptions of this region being the core and origin of these past abrupt climate changes.