Polar bears are susceptible to climate warming because of their dependence on sea ice, which is declining rapidly. We present the first evidence for a genetically distinct and functionally isolated group of polar bears in Southeast Greenland. These bears occupy sea-ice conditions resembling those projected for the High Arctic in the late 21st century, with an annual ice-free period that is >100 days longer than the estimated fasting threshold for the species. Whereas polar bears in most of the Arctic depend on annual sea ice to catch seals, Southeast Greenland bears have a year-round hunting platform in the form of freshwater glacial mélange. This suggests that marine-terminating glaciers, although of limited availability, may serve as previously unrecognized climate refugia. Conservation of Southeast Greenland polar bears, which meet the criteria for recognition as the world’s 20th polar bear subpopulation, is necessary to preserve the genetic diversity and evolutionary potential of the species.

Detailed methods are found in the main text and Supplemental material of Laidre et al. (2022). Citation: Kristin L. Laidre, Megan A. Supple, Erik W. Born, Eric V. Regehr, Øystein Wiig, Fernando Ugarte, Jon Aars, Rune Dietz, Christian Sonne, Peter Hegelund, Carl Isaksen, Geir B. Akse, Benjamin Cohen, Harry L. Stern, Twila Moon, Christopher Vollmers, Russ Corbett-Detig, David Paetkau, Beth Shapiro. 2022. Data from: Glacial ice supports a distinct and undocumented polar bear subpopulation persisting in late 21st-century sea-ice conditions, Science 376 (6599): 1333-1338. https://doi.org/10.1126/science.abk2793