A Holocene fjord record from Greenland reveals exceptional Atlantic water influence during minimum ice-sheet extent

The Holocene Thermal Maximum has been considered an analog for near-future climate. Terrestrial records show that this period culminated in Southwest Greenland with the Greenland Ice Sheet retreating behind its present-day position. However, there is a paucity of Holocene coastal marine records proximal to the ice sheet from which to infer marine conditions. Here we present a multi-proxy record from Nuup Kangerlua covering the past ~10,500 years, supported by a one-year sediment trap time-series. We infer modern sea-surface conditions comparable to those following the fjord’s deglaciation from 10,000 to 8000 calibrated years before present. Warmer temperatures led to a period of pronounced meltwater discharge and peak marine productivity by 7500 calibrated years before present. We detect an exceptional oceanographic regime with no recent analog from ~7000 to 3000 calibrated years before present, when reduced ice-sheet extent was coeval with entrainment of subpolar mode water (of Atlantic origin) into the fjord.