SOURCE: The Guardian
DATE: July 20, 2020
SNIP: Scientists have predicted for the first time when, where and how polar bears are likely to disappear, warning that if greenhouse gas emissions stay on their current trajectory all but a few polar bear populations in the Arctic will probably be gone by 2100.
By as early as 2040, it is very likely that many polar bears will begin to experience reproductive failure, leading to local extinctions, according to a study published in Nature Climate Change.
The study examines how the bears will be affected under two different greenhouse gas emissions scenarios. The researchers found that under a business-as-usual emissions scenario, polar bears will likely probably only remain in the Queen Elizabeth Islands – the northernmost cluster in Canada’s Arctic archipelago – at the end of the century. And even if greenhouse gases are moderately mitigated, it is still likely that the majority of polar bear populations in the Arctic will experience reproductive failure by 2080.
Scientists estimate that there are fewer than 26,000 polar bears left, spread out across 19 different subpopulations that range from the icescapes of Svalbard, Norway, to Hudson Bay in Canada to the Chukchi Sea between Alaska and Siberia. Polar bears are unable to find enough sustenance on land and rely on sea ice from which to hunt. They often stake out seal breathing holes in the ice, waiting hours for a blubbery meal to break the surface. But as that sea ice declines because of climate change, so, too, will the polar bears.
Polar bears draw on energy reserves built up during the winter hunting season to make it through lean summer months on land or time spent on ice in unproductive waters. Though the bears are used to fasting for months, their body condition, reproductive capacity and survival will eventually diminish if they are forced to go too long without food. In Alaska’s southern Beaufort Sea population, biologists have already seen polar bear numbers drop 25– 50% during low ice periods when the bears have been forced to fast for too long. And in western Hudson Bay, one of the southernmost polar bear habitats, the population has declined by roughly 30% since 1987.
“Even if we mitigate emissions, we are still going to see some subpopulations go extinct before the end of the century,” Molnár said. This includes the polar bears in the vulnerable, southernmost ice areas of western Hudson Bay, Davis Strait, and southern Hudson Bay.