Global warming is an increasingly pressing issue, with drastic implications for the environment and all its inhabitants. In particular, changes in climatic conditions have an immense impact on wildlife, and grizzly bears are no exception. Over the last few decades, grizzly bear populations in the northern hemisphere have begun to decline as the earth’s temperature has risen. To gain a better understanding of how global warming affects grizzly bears, it is important to analyze the impact it has on the grizzly bear’s habitat, diet and reproduction.
Most vulnerable to global warming are those grizzly bears whose habitats are located in the arctic or subarctic regions. As global temperatures increase, sea ice melts and snow packs recede, drastically transforming the landscape and threatening species adapted to cold climates. For example, a recent study commissioned by the U.S. Fish and Wildlife Service suggests that if no steps are taken to curb climate change, the southernmost point of the grizzly bear population in the United States will shift northward by as much as 475 miles over the next century. This would effectively eliminate grizzly bears from the contiguous United States, leaving only populations in Alaska, Canada and Russia.
Aside from physically altering their habitats, global warming is also hampering the grizzly bear’s diet. Warmer temperatures are leading to changes in species availability and dietary needs. For instance, whitebark pine, a staple food source of grizzlies in parts of the western United States, has decreased in abundance due to increased outbreaks of devastating pine beetle infestations facilitated by warmer weather and extended summers. Likewise, in Alaska, changes in the sea ice are leading to a decrease in other important grizzly bear food sources such as Pacific salmon and Pacific herring.
The changes in food supply are having an enormous impact on reproductive success. As the availability of essential food sources has decreased, pregnancy rates among grizzly bears have dropped and cub survival has significantly declined since the middle of the 2000s. Moreover, grizzly bears, who typically hibernate for five to six months of the year, are now emerging from their dens earlier and earlier, a phenomenon linked to the effects of global warming. Emerging from hibernation too early disrupts the natural cycle of births and mating in grizzly bears, resulting in a disruption to both their reproductive success and future population size.
Global warming has severely disrupted the lives of the grizzly bear and continues to pose a major threat to their existence. While these effects will take time to become fully realized, steps are necessary now to ensure their survival. Governments, as well as private citizens, must take immediate action to reduce global warming and its effects on the environment. As stewards of the earth and its inhabitants, it is our ethical and social responsibility to be aware of the serious harms global warming poses and to take appropriate action. As the saying goes, “we’re in this together” — and that means looking out for our wild neighbors in the present and in the future.
