Photo credit: Daniel J. Cox @ NaturalExposures.com
With increasing concentrations of greenhouse gases in the atmosphere, scientists have become increasingly concerned with the possible impact of warming on the Arctic regions. “More warming means less ice in arctic waters” (6). The presence of ice in arctic water is crucial to polar bear survival. Not only do polar bears live on these ice masses, but also they use the ice as a platform to hunt seals, their major source of food. A study by Stirling and Derocher hypothesized “that polar bears will be significantly affected by long-term unidirectional changes in the distribution and abundance of different types of seas ice habitat and in the dates of both freeze-up and break-up” (6). To support their claim, they cited a reduced access to seals that will alter the productivity of the ocean, breeding habitat, and denning behaviors of polar bears (6).
As expressed in the thermoregulation and denning sections, polar bears have the ability to slow their metabolisms with a decrease in food availability; however, this mechanism is not capable of sustaining polar bear populations alone. As a result of a decrease in hunting grounds and a decrease in food supply, polar bears move inland (22). In the Western Hudson Bay, where polar bears are already exhibiting changes in distribution as a result of early sea ice breakups, researchers have noted a decrease in survivorship and an increase in death due to starvation and freezing (22). Regehr et al. suggests that the Hudson Bay, although it is the first Arctic area to see polar bears exhibit movement inland, will not be the first if the concentration of greenhouse gases continues to increase.
While polar bears may not be the most ideal model species in which to study thermoregulation, the study of their physiology is largely important to current conservation efforts. By studying thermoregulation in polar bears, as well as behavioral patterns, we can combine our knowledge of these two areas and predict their survival with the expected warming trends. Polar bears are currently the flagship species for Arctic regions and global warming. This has prompted several studies to predict or model the future density of polar bear populations in the Arctic region.