Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines

Biology Letters
By: , and 



Loss of Arctic sea ice owing to climate change is the primary threat to polar bears throughout their range. We evaluated the potential response of polar bears to sea-ice declines by (i) calculating generation length (GL) for the species, which determines the timeframe for conservation assessments; (ii) developing a standardized sea-ice metric representing important habitat; and (iii) using statistical models and computer simulation to project changes in the global population under three approaches relating polar bear abundance to sea ice. Mean GL was 11.5 years. Ice-covered days declined in all subpopulation areas during 1979–2014 (median −1.26 days year−1). The estimated probabilities that reductions in the mean global population size of polar bears will be greater than 30%, 50% and 80% over three generations (35–41 years) were 0.71 (range 0.20–0.95), 0.07 (range 0–0.35) and less than 0.01 (range 0–0.02), respectively. According to IUCN Red List reduction thresholds, which provide a common measure of extinction risk across taxa, these results are consistent with listing the species as vulnerable. Our findings support the potential for large declines in polar bear numbers owing to sea-ice loss, and highlight near-term uncertainty in statistical projections as well as the sensitivity of projections to different plausible assumptions.

Publication type Article
Publication Subtype Journal Article
Title Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines
Series title Biology Letters
DOI 10.1098/rsbl.2016.0556
Volume 12
Year Published 2016
Language English
Publisher Royal Society Publishing
Contributing office(s) Alaska Science Center Biology MFEB
Description Article 20160556; 5 p.
First page 1
Last page 5
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