Arctic marine sediments reveal massive coastal permafrost erosion during the Bølling-Allerød warm period

Abstract The Bølling-Allerød interstadial (14.7-12.9 kyr BP), during the last deglaciation, was characterized by rapid retreat of ice sheets and significant sea level rise (Meltwater Pulse 1A, MWP-1A; 14.7-14.3 kyr BP). Yet, the response of the terrestrial cryosphere during this period of abrupt climate change remains elusive. Here we present a multi-proxy analysis of a sediment record from the upper slope of the Svalbard continental margin that encompasses the last 30 kyr. We show that the Last Glacial Maximum was characterised by the deposition of bedrock material locally sourced by the Barents Sea Ice Sheet. Instead, during MWP-1A permafrost-derived material rich in biospheric carbon became the dominant source of sediments despite the lack of any direct connection with permafrost deposits. Our results suggest massive erosion of Yedoma permafrost deposits during abrupt sea level rise followed by long-range sea ice transport within the Transpolar Drift towards the Arctic Ocean gateway. Overall, we show how permafrost is susceptible to large-scale remobilization in a scenario of rapid warming and sea level rise.