Weaker Nordic Seas convection and bottom water warming during Greenland stadials

Deep water formation maintains stronger bottom currents in the modern Nordic Seas, supplying overflow waters which feed the Atlantic Meridional Overturning Circulation (AMOC). Past glacial millennial-scale abrupt cold-warm climate transitions, called Dansgaard-Oeschger (D-O) events, and their driving mechanisms remain poorly understood. Here, we combine the palaeo-flow bottom-current strength proxy (´sortable silt´) with geochemical (benthic foraminiferal Mg/Ca and δ ¹⁸ O) analyses from an archive from the central eastern Nordic Seas. During most cold D-O and Heinrich stadials, intermediate waters warmed and bottom currents were weak, suggesting that the inflowing Atlantic water had thickened, and convection was suppressed. Warm interstadials had opposite conditions, with stronger bottom currents and cold intermediate waters. Bottom currents weakened during the long interstadial transitional cooling phases. Prior to the stadial onsets, bottom currents and advection of warm Atlantic surface water were revived, likely triggering cryosphere and salinity changes that resulted in stadial climate.