Polar bears and their prey have evolved to living in the extreme conditions of the Arctic. Polar bears and seals are dependent on sea-ice for foraging, resting, and reproduction. The Arctic ecosystem was shaped by climate and continues to be driven today by climate. Polar bears and ice seals, primarily ringed seals, serve as key indicators of the effects of climate change on the Arctic environment. Today, polar bear populations are facing threats previously unprecedented during recorded history in the Arctic. Recent climate change scenarios based upon modeling of climate trend data predict that the Arctic region will experience major changes in the upcoming decades. On the most drastic end of the spectrum one model predicts that the Arctic basin may be void of ice within 50 years. Other models have shown that ice thickness has decreased by 40% during the past 30 years and the average annual extent of ice coverage in the polar region has diminished substantially, with an average annual reduction of over 1 million square kilometers.
While the ultimate or progressively evolving effects of climatic change on polar bear populations is not certain, we do recognize that even minor climate changes could likely have a profound effect on polar bears.
• Climate changes on prey species will have a negative effect on polar bears
o increased snow can result in reduced success in successfully entering seal birth lairs
o decreased snow or increased seasonal rain patterns could effect seal pupping by not providing adequate snow for construction of birth lairs or if rain fall by collapsing birth lairs thus reducing seal productivity
o prey reductions could effect polar bear condition and ultimately cub production and survival
• Changes that alter the period of ice coverage could affect distribution and impact polar bears
o bears may spend greater amounts of time on land
o extended use of terrestrial areas would ultimately effect physical condition of bears when forced to rely on fat stores
o decreased physical condition could effect production and survival
o bears using deteriorating pack ice may experience increased energetic costs associated with movements and swimming
• Denning could be impacted by unusual warm spells
o access to high quality denning areas may be limited or restricted
o use of less desirable denning habitat could have impacts on reproduction and survival
o rain or warming could directly cause snow dens to collapse or be opened to ambient conditions
o loss of thermal insulative properties in opened dens could affect litter survival
While the ultimate or progressively evolving effects of climatic change on polar bear populations is not certain, we do recognize that even minor climate changes could likely have a profound effect on polar bears.
• Climate changes on prey species will have a negative effect on polar bears
o increased snow can result in reduced success in successfully entering seal birth lairs
o decreased snow or increased seasonal rain patterns could effect seal pupping by not providing adequate snow for construction of birth lairs or if rain fall by collapsing birth lairs thus reducing seal productivity
o prey reductions could effect polar bear condition and ultimately cub production and survival
• Changes that alter the period of ice coverage could affect distribution and impact polar bears
o bears may spend greater amounts of time on land
o extended use of terrestrial areas would ultimately effect physical condition of bears when forced to rely on fat stores
o decreased physical condition could effect production and survival
o bears using deteriorating pack ice may experience increased energetic costs associated with movements and swimming
• Denning could be impacted by unusual warm spells
o access to high quality denning areas may be limited or restricted
o use of less desirable denning habitat could have impacts on reproduction and survival
o rain or warming could directly cause snow dens to collapse or be opened to ambient conditions
o loss of thermal insulative properties in opened dens could affect litter survival
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