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Threat to Polar Bears Still Reversible if Emissions Cut

Polar Bears are one of several species at risk due to global warming and climate change. Polar Bears are one of several species at risk due to global warming and climate change.

The polar bear has been the poster child for the movement to cut greenhouse gas emissions for most of the 21st century. The ice in the arctic is disappearing because of global warming, and that presents a direct threat to the polar bear, the most popular and recognizable of the at-risk species in the area. A few years ago, studies from leading international universities suggested that the polar bear would be close to extinct by about 2050. Recent studies support that finding, but indicate that all hope is not yet lost.

Dr. Steven Amstrup, leader of a US Geographical Survey team, was one of the first to suggest that the earth was on an irreversible course towards the destruction of the Arctic, but now reports that if industrial societies act quickly to cut emissions, the polar bear’s habitat might still be saved.

Polar bears need ice to travel on for hunting and mating. Without that ice available, some bears could starve while others are simply unable to find a mate and reproduce. Other polar bears have ended up foraging closer to cities, which is not a viable long-term survival strategy. Current estimates are that 20,000-25,000 polar bears remain in the wild, with several populations in decline.

Another component of the threat to polar bear populations is the encroachment of another bear species, the grizzly bear. In parts of Manitoba, Canada, grizzly bears have been spotted in areas historically void of them, but home to polar bears. These sightings have been rare since the first observation about 15 years ago, but they are increasing.

This year, the second confirmed example of a “prizzly bear” was discovered when a hunter shot an animal he first thought to be a polar bear. DNA evidence revealed that it was a hybrid species, the offspring of one grizzly bear parent and one polar bear parent. The previous confirmed case of a grizzly-polar bear hybrid was in 2006, when the specimen was shot by another hunter.

Grizzlies and polar bears live, hunt, and mate on different terrain – polar bears on ice, grizzly bears on land – but the changing climate seems to be causing an increasing overlap of the two species ranges. Dr Brendan Kelly of the US National Marine Mammal Laboratory is one of the people advancing this theory, and points to other examples of hybridization as also potentially problematic.

For example, the bowhead whale and the right whale are thought to be inter-breeding, with one example of a hybrid possibly spotted this year. Both species are considered at risk, with the bowhead inhabiting the Arctic Ocean, and the right whale moving from the Atlantic into bowhead territory as the oceans continue to warm.

Belugas and narwhals have been known to produce hybrids since the first discovery of an interspecies specimen in the 1980s. But the narwhal is one of the few whale or porpoise species to spend a long stretch of the winter months near arctic ice, where they eat halibut and squid with little competition for those food animals. But as the ice disappears, their exclusive hunting grounds will become more attractive to other species. In fact, scientists think the narwhal may disappear before the polar bear based on its inability to adjust to loss of habitat.

Dall’s porpoise and the harbor porpoise have already created extensive examples of hybrids between the two species. The harbor porpoise is increasingly moving into the territory of the Dall’s porpoise as the ocean warms. Harbor porpoises have also been starving in European waters, where ocean warming has led to a decrease in available food sources, such as a fish called the sand eel, which constitutes the primary food source for the harbor porpoise and several species of seabird. The sand eels feed on cold-water plankton, which cannot survive in the warming oceans. As a result, the number of sand eels is declining and affecting myriad species in the process. This is a fine example of the interconnectedness of organisms, and why the loss of even a single species can be catastrophic.

Dr. Kelly describes hybridization as just one more way that the changing arctic climate will affect the organisms living there. Not the least of which is the ever popular polar bear.

Hybridization, loss of habitat, scarcity of prey animals – all of these are threats to the earth’s polar bear population, and all are a result of climate change. Is there hope for industrial nations to make the necessary changes to cut greenhouse gas emissions in time to save species like the polar bear and narwhal? Maybe. A lot depends on the consumer. After all, it’s the demand for product that drives industry. Each of us can contribute to conservation efforts by becoming educated about the issues, reducing our own carbon footprint, and rethinking the nature of our purchases and consumption of resources. For those even more motivated, there are numerous conservation groups to get involved with or donate to.


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Polar Bears are at risk due to climate change, but it's not too late to help this endangered species.
Last modified on Friday, 19 October 2012 17:37

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