| Summary: | Investigating past interglacial climates not only help to understand how the climate system operatesin general, it also forms a vital basis for climate predictions. We reconstructed vertical stratificationchanges in temperature and salinity in the North Atlantic for a period some 400 ka ago (MIS11),an interglacial time analogue of a future climate. As inferred from a unique set of biogeochemical,geochemical, and faunal data, the internal upper ocean stratification across MIS 11 shows distinctdepth-dependent dynamical changes related to vertical as well as lateral shifts in the upper Atlanticmeridional circulation system. Importantly, transient cold events are recognized near the end of thelong phase of postglacial warming at surface, subsurface, mid, and deeper water layers. These datademonstrate that MIS 11 coolings over the North Atlantic were initially triggered by freshwater inputat the surface and expansion of cold polar waters into the Subpolar Gyre. The cooling signal was thentransmitted downwards into mid-water depths. Since the cold events occurred after the main deglacialphase we suggest that their cause might be related to continuous melting of the Greenland ice sheet, amechanism that might also be relevant for the present and upcoming climate.
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