Polar bears are on the way to extinction. These mammals, which are found throughout the Arctic region, are being seriously affected by the decrease in Arctic ice, which is already expected to disappear completely during the summers by 2050. Thus, with its ecosystem in process of destruction, the polar bear will not be able to survive as a species beyond the end of the century, as a study published inNature Climate Change.
The polar bear travels long distances over vast, desolate expanses, usually on drifting ice floes, looking for seals, its main prey. Butthe Arctic is warming three times faster than the planet as a whole, so polar bears have fewer and fewer options for hunting seals. Specifically, the study predicts that 12 of the 13 polar bear subpopulations will decimate in the next 80 years.
According to statements by one of the main authors of the study for the AFP agency, Steven Amstrup: “The bears face a very long period of fasting before the ice freezes again and they can go out for food.” Therefore, if polar bears do not eat enough to reach their normal body weight before the fast begins,they will not have enough stored energy to sustain themselves.
The study analyzed the demographic trends observed during 1979–2016, establishing the probability, timing, and order of future demographic impacts by estimating threshold numbers of days that polar bears can fast before the birth of cubs or adult survival is affected and decline rapidly.
The results showed that the birth and survival impact thresholds may already have been exceeded in some subpopulations. They also suggest that, in a scenario of high greenhouse gas emissions,“Reproduction and survival in decline will jeopardize the persistence of all Arctic subpopulations, with a few exceptions, by the year 2100”, as cited in the article.
There’s a solution?
While it is true that the prediction of the disappearance of polar bears would occur in a scenario of high emissions, and that moderate mitigation of these emissions may also significantly prolong their existence, “it is unlikely that it will prevent mass disappearances in some subpopulations within this century ”, according to the authors of the study.
Today there are approximately 25,000 polar bears in the wild. Except for a subspecies of brown bear, the polar bear is the largest and most powerful carnivore on earth. It has no natural predators and it does not know the fear of humans; although, under the circumstances, maybe it should.
Reference:
Fasting season length sets temporal limits for global polar bear persistence
Péter K. Molnár, Cecilia M. Bitz, Marika M. Holland, Jennifer E. Kay, Stephanie R. Penk & Steven C. Amstrup. (2020) ‘Nature Climate Change’
