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Summary: A continuous, well-preserved sedimentary record of multi-decadal benthic ostracode and foraminifera faunal assemblages and sub-centennial shell isotope geochemistry extends over 2,000 years and reveals short-term paleoenvironmental changes on the Mackenzie continental shelf. Microfossil faunal assemblage composition, biogenic silica, ostracode and foraminifera δ¹⁸O and δ¹³C records reflect generally cold conditions with multidecadal variability in temperature, salinity, and terrestrially derived inputs from the Mackenzie River. Our records show summer warming oscillations during the Medieval Climate Anomaly, and a variable, colder climate from ~1250 to 1900 CE. Changes in proxies within the last ~60 years suggest longer periods of open water with greater river influx, increased productivity, and periods of higher turbidity in the bottom environment.. Because high resolution sediment records on high latitude continental shelves are rare, this record is important to understand past natural climate variability and contextualize benthic ecosystem change in the modern environment due to anthropogenic forcings. Because half of the Arctic Ocean is comprised of shallow continental shelves, which encounter a wide range of environmental conditions over seasonal to centennial timescales, it is essential to improve the understanding and modeling of patterns and causes of Arctic climate change in coastal regions.

For more information about Land-Sea Linkages in the Arctic, please see our project webpage at https://www.usgs.gov/programs/climate-research-and-development-program/science/land-sea-linkages-arctic