For the first time, ESA evaluations can include impacts on polar bears from greenhouse gas emissions
Science
31 Aug 2023
Vol 381, Issue 6661
pp. 949–951
Abstract
In 2008, projections that up to two-thirds of the world’s polar bears could disappear by mid-century (1) led to polar bears becoming the first species listed under the US Endangered Species Act (ESA) because of threats from anthropogenic climate warming. Updated analyses (2) corroborated the 2008 projections and showed a linear but inverse relationship between Arctic sea ice extent and global mean temperature. Despite the relationship between warming and sea ice loss, absence of a quantitative link between anthropogenic greenhouse gas (GHG) emissions, sea ice loss, and declining polar bear vital rates has foiled full ESA implementation for polar bears. By quantifying the relationship between anthropogenic GHG emissions and polar bear recruitment, we show that sensitivities to cumulative anthropogenic emissions explain observed population trends, allow estimation of demographic impacts from new emissions sources, and enable ESA procedures to assess global warming impacts of proposed actions—along with impacts on the ground.
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References and Notes
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Science
Volume 381 | Issue 6661
1 September 2023
Copyright
Copyright © 2023 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
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Published in print: 1 September 2023
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Acknowledgments
S.C.A. received funding from Polar Bears International. C.M.B. received funding from National Science Foundation grant OPP-2237964. The authors thank T. McDonald for advice on statistical procedures, and P. Molnár for providing data for recruitment failure as a function of fasting duration (10). Data and code for replication are available at Zenodo (14).
Authors
Affiliations
Polar Bears International, Bozeman, MT, USA.
Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA.
Atmospheric Sciences, University of Washington, Seattle, WA, USA.
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- Steven C. Amstrup
- Cecilia M. Bitz
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Unlock the Endangered Species Act to address GHG emissions.Science381,949-951(2023).DOI:10.1126/science.adh2280
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