During the 2017/18 Northern Hemisphere cold season, sea ice extent in the Bering Sea was less than any winter in the observed or reconstructed past. The eastern and northern Bering Sea covers a shallow and expansive continental shelf that has historically exhibited 40%–100% ice cover at its annual winter maximum. This sea ice provides many important ocean climate and ecosystem services. For example, winter ice insulates warmer ocean waters from extreme cold in the atmosphere. During spring, algae growth on the undersurface of sea ice
initiates the annual onset of biological productivity (Szymanski and Gradinger 2016). The seasonal ice cover is critical to the regional climate, marine ecosystems, societal expectations, and economics through maintenance of a thermal barrier that separates two distinct temperature-adapted marine ecosystems in the northern and southern portions of the Bering Sea shelf (Schumacher et al. 1983; Mueter and Litzow 2008). We utilized remote sensing derived ice extent products for ice context; governmental and academic investigations, media, and public reports for impacts; and the Community Earth System Model’s Large Ensemble Project (CESM-LENS) for assessment of the relative likelihoods of current low ice extent.


Thoman, R.L., Bhatt, U.S., Bieniek, P.A., Brettschneider, B.R., Brubaker, M., Danielson, S.L., Labe, Z., Lader, R., Meier, W.N., Sheffield, G., and Walsh, J.E.. 2020. The record low Bering Sea ice extent in 2018: Context, impacts and an assessment of the role of anthropogenic climate change. Bulletin of the American Meteorological Society. 1011: s53-s58. https://journals.ametsoc.org/bams/article/101/1/S53/346389/The-Record-Low-Bering-Sea-Ice-Extent-in-2018. DOI: https://doi.org/10.1175/BAMS-D-19-0175.1.