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Predicting climate change impacts on polar bear litter size.
Péter K Molnár1, Andrew E Derocher, Tin Klanjscek
1Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2G1. pmolnar@ualberta.ca
Nature Communications
|February 10, 2011
Summary
Climate warming threatens polar bears by reducing litter sizes due to energy limitations. Earlier sea ice breakup significantly increases reproductive failure and decreases cub survival, jeopardizing polar bear populations.
Area of Science:
- Ecology
- Climate Change Biology
- Conservation Science
Background:
- Predicting climate warming's ecological impacts is crucial for species conservation.
- Population models struggle to incorporate future warming due to unmeasurable reproduction and survival rates.
- Polar bears face threats from climate change, impacting their reproductive success.
Purpose of the Study:
- To predict polar bear litter size and reproductive success under future climate warming scenarios.
- To assess the impact of earlier sea ice breakup on polar bear population viability.
- To project potential declines in litter size for polar bear populations globally.
Main Methods:
- Utilized mechanistic energy budget models.
- Employed data obtainable under current environmental conditions.
- Simulated future conditions based on projected sea ice break-up dates.
Main Results:
- Predicted significant declines in polar bear litter size in western Hudson Bay due to climate warming.
- Projected increased reproductive failure rates for pregnant polar bears with earlier sea ice break-up (40-73% failure if 1 month earlier, 55-100% if 2 months earlier).
- Estimated mean litter size decreases of 22-67% (1 month earlier) and 44-100% (2 months earlier).
Conclusions:
- Climate warming-induced litter size declines jeopardize polar bear population viability.
- Similar declines may affect over one-third of the global polar bear population.
- The timeline of these declines is dependent on climate model-specific sea ice predictions.
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