LAUSR

Significance Dansgaard-Oeschger (D-O) events are abrupt atmospheric warming events in Greenland that occurred repeatedly during the last glacial period. Combining proxy records from an ice core and a sediment core, we reconstruct sea ice conditions in the Baffin Bay and the Labrador Sea during several D-O events between 34 and 42 thousand years ago. Our results reveal in detail that widespread sea ice decline was synchronous with the atmospheric warming of the D-O events, highlighting the importance of sea ice decline in amplifying abrupt high-latitude climate warming. We also find re-expansion of seasonal sea ice during the late phase of warm interstadial periods, which likely contributed to a feedback loop in the sub-polar North Atlantic driving the climate system back to cold stadial conditions.