Mid-Holocene sea-ice dynamics and climate in the northeastern Weddell Sea inferred from an Antarctic snow petrel stomach oil deposit

Abstract. Understanding past variability in Antarctic sea ice is of critical importance to determine how it regulates global climate processes and biogeochemistry, and Southern Ocean marine ecosystems. Records of changes in Holocene sea-ice extent in the Weddell Sea is limited to a few marine sediment cores and inferences from continental ice cores. Here we present a novel record of sea-ice and climate from ~6700 – 2000 cal. yr BP based on accumulation rates and multi-proxy geochemical analyses of a snow petrel stomach-oil deposit from the Heimefrontfjella Range, Dronning Maud Land, East Antarctica. Three different sea-ice configurations are interpreted from the record. From 6700 – 6200 cal. yr BP there was a period of low sea ice cover and extensive polynyas associated with warmer temperatures and regional ice shelf retreat. From 6200 – 4700 cal. yr BP there was a gradual transition to more extensive sea-ice configuration and a switch towards foraging in coastal polynyas at the retreating ice-shelf front. Finally, between 4600 – 2000 cal. yr BP increased sea ice extent restricted access to foraging grounds which by ~6700 cal. yr BP resulted in abandonment of the nest. Our results highlight how specific Holocene sea-ice configurations can be interpreted from the geochemical composition of snow petrel stomach-oil deposits, providing insight into the interactions between oceanographic forcing, climate change, ice-shelf extent and ecosystem adaptation. We also show, for the first time, the utility of phytol and cholesterol analysis for understanding past avian diet.