Biomarker record of sediment core MSM44_353-3

Arctic sea ice is a critical component of the climate system, known to influence ocean circulation, earth's albedo, and ocean-atmosphere heat and gas exchange. Current developments in the use of IP25 (a sea ice proxy with 25 carbon atoms only synthesized by Arctic sea ice diatoms) have proven it to be a suitable proxy for palaeo-sea ice reconstructions over hundreds of thousands to even million years timescales. In the NE-Baffin Bay, off NW-Greenland, Melville Bugt is a climate-sensitive region characterized by strong seasonal sea ice variability and strong melt-water discharge from the Greenland Ice Sheet (GIS). Here, we present a centennial-scale resolution Holocene sea ice record, based on IP25 and open-water phytoplankton biomarkers (brassicasterol, dinosterol and HBI III) using core GeoB19927-3 (73°35.26' N, 58°05.66' W). Seasonal to ice-edge conditions near the core site is documented for most of the Holocene period with some significant variability. A cold interval, in the lower-most part, characterized by extensive sea ice cover and very low local productivity is succeeded by an interval (~9.4-8.5 ka BP)) with reduced sea ice cover, enhanced GIS spring melting, and strong influence of the West Greenland Current (WGC) in the earliest part of the record. From ~8.5 untill ~7.8 ka BP, a cooling event is recorded by ice algae and phytoplankton biomarkers. They indicate an enhanced sea ice cover, possibly related to the opening of Nares Strait, which may have led to an increased influx of Polar Water into NE-Baffin Bay. The interval between ~7.8 and ~3.0 ka BP is characterized by generally reduced sea ice cover with millennial-scale variability of the (late winter/early spring) ice-edge limit, increased open-water conditions (polynya-type), and a dominant WGC carrying warm waters at least as far as the Melville Bugt area. During the last ~3.0 ka BP, our biomarker records do not reflect the late Holocene 'Neoglacial cooling' observed elsewhere in the Northern Hemisphere, possibly due to the persistent influence of the WGC and interactions with the adjacent fjords. Peaks in HBI III at about ~2.1 and ~1.3 ka BP, interpreted as persistent ice-edge situations might, correlate with the Roman Warm Period (RWP) and Medieval Climate Anomaly (MCA), respectively, in-phase with the North Atlantic Oscillation (NAO) mode. When integrated with marine and terrestrial records from other circum-Baffin Bay areas (Disko Bay, the Canadian Arctic, the Labrador Sea), the Melville Bugt biomarker records point to close ties with high Arctic and Northern Hemispheric climate conditions, driven by solar and oceanic circulation forcings.