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. From ~7,000 to 3,000 years ago, reduced ice-sheet extent coincided with the inflow of warm Atlantic waters into the Nuup Kangerlua fjord in Greenland, leading to an exceptional oceanographic regime, according to sedimentological, paleoclimatic, and paleobiological data from the past 10,500 years.