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Kristin Laidre

Principal Oceanographer

Professor, School of Aquatic + Fishery Sciences





Department Affiliation

Polar Science Center


B.S. Zoology, University of Washington - Seattle, 1999

Ph.D. Aquatic & Fishery Sciences, University of Washington - Seattle, 2003

Kristin Laidre's Website



2000-present and while at APL-UW

Thick and old sea ice in the Beaufort Sea during summer 2020/21 was associated with enhanced transport

Moore, G.W.K., M. Steele, A.J. Schweiger, J.L. Zhang, and K.L. Laidre, "Thick and old sea ice in the Beaufort Sea during summer 2020/21 was associated with enhanced transport," Commun. Earth Environ., 3, doi:10.1038/s43247-022-00530-6, 2022.

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30 Aug 2022

The Arctic Ocean has seen a remarkable reduction in sea ice coverage, thickness and age since the 1980s. These changes are most pronounced in the Beaufort Sea, with a transition around 2007 from a regime dominated by multi-year sea ice to one with large expanses of open water during the summer. Using satellite-based observations of sea ice, an atmospheric reanalysis and a coupled ice-ocean model, we show that during the summers of 2020 and 2021, the Beaufort Sea hosted anomalously large concentrations of thick and old ice. We show that ice advection contributed to these anomalies, with 2020 dominated by eastward transport from the Chukchi Sea, and 2021 dominated by transport from the Last Ice Area to the north of Canada and Greenland. Since 2007, cool season (fall, winter, and spring) ice volume transport into the Beaufort Sea accounts for ~45% of the variability in early summer ice volume — a threefold increase from that associated with conditions prior to 2007. This variability is likely to impact marine infrastructure and ecosystems.

Glacial ice supports a distinct and undocumented polar bear subpopulation persisting in late 21st-century sea-ice conditions

Laidre, K.L. and 18 others including E.V. Regehr, B. Cohen, and H.L. Stern, "Glacial ice supports a distinct and undocumented polar bear subpopulation persisting in late 21st-century sea-ice conditions," Science, 376, 1333-1338, doi:10.1126/science.abk2793, 2022.

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17 Jun 2022

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 criteria for recognition as the world’s 20th polar bear subpopulation, is necessary to preserve the genetic diversity and evolutionary potential of the species.

A polar bear paleogenome reveals extensive ancient gene flow from polar bears into brown bears

Wang, M.-S., and 14 others including K.L. Laidre, "A polar bear paleogenome reveals extensive ancient gene flow from polar bears into brown bears," Nat. Ecol. Evol., 6, 936-944, doi:10.1038/s41559-022-01753-8, 2022.

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16 Jun 2022

Polar bears (Ursus maritimus) and brown bears (Ursus arctos) are sister species possessing distinct physiological and behavioural adaptations that evolved over the last 500,000 years. However, comparative and population genomics analyses have revealed that several extant and extinct brown bear populations have relatively recent polar bear ancestry, probably as the result of geographically localized instances of gene flow from polar bears into brown bears. Here, we generate and analyse an approximate 20X paleogenome from an approximately 100,000-year-old polar bear that reveals a massive prehistoric admixture event, which is evident in the genomes of all living brown bears. This ancient admixture event was not visible from genomic data derived from living polar bears. Like more recent events, this massive admixture event mainly involved unidirectional gene flow from polar bears into brown bears and occurred as climate changes caused overlap in the ranges of the two species. These findings highlight the complex reticulate paths that evolution can take within a regime of radically shifting climate.

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In The News

'Wholly unexpected': These polar bears can survive with less sea ice

The New York Times, Henry Fountain

The overall threat to the animals from climate change remains, but a new finding suggests that small numbers might survive for longer as the Arctic warms. See related articles on the UW News pinboard.

16 Jun 2022

Newly documented population of polar bears in Southeast Greenland sheds light on the species' future in a warming Arctic

UW News, Hannah Hickey

Scientists have documented a previously unknown subpopulation of polar bears living in Southeast Greenland. The polar bears survive with limited access to sea ice by hunting from freshwater ice that pours into the ocean from Greenland’s glaciers.

16 Jun 2022

How to count polar bears

The New York Times Magazine, Malia Wollan

Get an aerial vantage. If you spot fresh tracks, follow them until you find an animal.

15 Feb 2022

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