The spatial and temporal variability of Arctic sea ice is important for understanding regional and global climate change and its ecological impacts. Proxy-based methods are required to study long-term Arctic sea-ice variability and its role in global climate because the satellite sea-ice record is less than 40 years long. This study tests the lipid-biomarker-based sea-ice proxy PIP₂₅, along a transect in the Bering-Chukchi Sea and finds it to accurately reflect the satellite-based sea-ice coverage. Our results showed that the ice-algal OC contribution varies systematically along the sea-ice gradient, accounting for up to 60 % of total sedimentary OC underlying the summer ice edge. Phytoplankton production, on the other hand, contributes about 60–70% to sedimentary OC at the winter ice edge on the Bering Sea shelf and gradually decreases towards the north. The terrestrial OC proportion of sedimentary TOC is generally low, averaging 25±5% except the northernmost station (80°N).
 

Sea ice,Biomarker,HBIs,Arctic