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Abstract

The cyclic growth and decay of continental ice sheets can be reconstructed from the history of global sea level. Sea level is relatively well-constrained for the Last Glacial Maximum (LGM, 26,500-19,000 years ago, 26.5-19 ka) and the ensuing deglaciation. However, sea-level estimates for the period of ice-sheet growth before the LGM vary by > 60 m, an uncertainty comparable to the sea-level equivalent of the contemporary Antarctic Ice Sheet. Here we constrain sea level prior to the LGM by reconstructing the flooding history of the shallow Bering Strait since 46 ka. Our data constraint on Bering Strait flooding are nitrogen isotope measurements in organic matter bound in the planktonic foraminifer Neogloboquadrina pachyderma from four sediment cores in the Arctic Ocean, dating back to ~50,000 years before present. These data extend the previous measurements of Farmer et al., 2021 (https://doi.org/10.1038/s41561-021-00789-y). We additionally provide new Bayesian age-depth models for each sediment core based on existing radiocarbon (14C) measurements on N. pachyderma. The nitrogen isotope data are compared with a suite of reconstructions of global mean sea-level and relative sea level at the Bering Strait from glacial isostatic adjustment modeling covering the last 120,000 years.