Polar bears are likely to be almost completely extinct by the end of this century if climate change continues at its current pace, a new study warns. Scientists already knew polar bears were in deep trouble—they depend on sea ice to survive, and sea ice is disappearing—but researchers say they were able to estimate a timeline based on the number of ice-free days expected in various regions in the years to come and the maximum amount of time the bears can survive—and nurse cubs—without food, the Guardian reports. The researchers, whose study was published in the journal Nature Climate Change, say some of the 19 polar subpopulations are likely to be gone by 2040 and by 2100, the only population remaining could be the bears of the Queen Elizabeth Islands in Canada's far north.
The researchers say that if the bears are unable to hunt for seals on sea ice, they will simply "run out of energy," leading to reproductive failures. In a "business-as-usual" scenario for greenhouse-gas emissions, "there is very little chance that polar bears would persist anywhere in the world, except perhaps in the very high Arctic in one small subpopulation," says lead researcher Peter K. Molnar, per the New York Times. He says that the picture for the bears will improve if emissions are reduced, but at this point, even if emissions drop to more moderate levels, we are "unfortunately going to lose some, especially some of the southernmost populations, to sea-ice loss." (Read more polar bears stories.)