Holocene Climate Variability in the Beaufort Sea, Arctic Ocean from Benthic Foraminifers, Stable Isotopes and Pollen

Satellite observations of declining Arctic sea-ice coverage underscore the importance of understanding Arctic climate variability on decadal to centennial timescales. A majority of marine proxy records from Arctic sediment cores, however, do not resolve sub-millennial-scale changes due to low sedimentation rates (< 1 cm kyr-1) in central Arctic Ocean basins and variable preservation of biogenic carbonate. Here we present benthic foraminiferal assemblages, stable isotopes and terrestrial pollen assemblages from HLY0205 core GGC19 collected at 369 m water depth in Barrow Canyon on the Beaufort Sea continental shelf-slope break. A linear age model from nine radiocarbon dates obtained on benthic foraminifera and mollusk material yields an average sedimentation rate of 67 cm kyr-1, providing for multidecadal to centennial scale sampling resolution. Benthic foraminifera are well preserved through the length of the core and dominated by E. excavatum, I. helenae, C. reniforme, and N. labradorica. Foraminiferal assemblages and isotopic records suggest broad changes in regional oceanography and productivity over the last 7000 calendar (cal) years. Abrupt shifts in foraminiferal assemblages around 5000, 1500, and 800 cal years BP may be related to changes in mid-depth ocean circulation (i.e., strength of the Atlantic Layer) or surface ocean processes (i.e., sea-ice formation and brine rejection) along the Beaufort Sea margin. The addition of terrestrial pollen reconstructions allow for the first coupled land-ocean paleoclimate record in the Western Arctic region.