A new study published recently in the journal Science has some good and bad news about polar bears. The study is based on research completed from 2008 to 2010, in which over two-dozen polar bears were captured and tagged with temperature loggers, and then tracked.
First the bad news. As most readers should be aware, the ice sheets upon which polar bears hunt are melting at an alarming rate, which is making it increasingly difficult for the bears to survive. They have less access to seals for less time, forcing them to swim much longer distances for less prey.
Until recently, there had been some hope that polar bears could enter a sort of “walking hibernation,” which would allow them to reduce their metabolic rate and survive on less food while prey was scarce. As it turns out, however, no such thing exists. The bears that were tracked were found to exhibit activities found in other non-hibernating, fasting animals.
There is good news from this study though. Researchers also discovered that polar bears can relegate their core body temperature in a phenomenon called “regional heterothermy.” The bears temporarily cool the outermost tissue of their core to create an insulating shell. This helps them to conserve energy for long swims. One bear managed a nine-day, 400-mile swim from shore to the floating ice where her prey lived. Along the way though, she lost about 22% of her body mass, and her cub.
Things aren’t looking up for polar bears. Hopefully, regional heterothermy will help them survive as ice melts, but if we don’t do something to stop and reverse that ice melt soon, they’ll be doomed to extinction. The melting of ice sheets around the North Pole is entirely because of human activity, namely CO2 and methane production, and if those numbers aren’t cut, we’ll begin to see even more deleterious effects on the Earth. A generation from now, polar bears might be looked at like the dodo: a creature unfortunately brought to extinction by human mistakes.