The question of what rising temperatures and melting sea ice will do to polar bears has concerned scientists for years now, but it’s only recently that they have been able to make projections that include hard numbers—and the outlook is grim. A recent study published in the Royal Society’s journal of biological research, Biology Letters, used statistical models to estimate what will happen to polar bear populations over the next several generations, and they found that they will likely decrease by a third over the next 30 to 40 years.
Polar bears rely on sea ice for survival. In order to hunt, they need to be able to follow ringed seals (their primary prey), and sea ice gives them a platform from which to ambush their prey. Without ice, they must swim into the ocean without any opportunity to rest, and without a platform from which to hunt. Unfortunately, another recent study has found that increased rates of melting ice have decreased polar bears’ window for hunting by seven weeks in the past 35 years—and that trend is likely to continue.
“Sea ice really is [polar bears’] platform for life,” said Kristin Laidre, who co-authored the sea ice study and is a researcher at the Polar Science Center. “They are capable of existing on land for part of the year, but the sea ice is where they obtain their main prey.”
As for the projections of polar bear population decline, some scientists actually think the estimates are too conservative. “It’s probably overly optimistic,” bear biologist Andrew Derocher told the CBC. Derocher, who works at the University of Alberta, says that the projections don’t account for the fact that one or two very bad years for sea ice can have a large effect on bear populations. He notes that projections don’t tend to include these exceptionally poor years: “If we look at 2016 for sea ice, it was a lot worse than anything else we’ve seen in the record.”
Derocher also noted that as bear habitats change, we may see more polar bears coming into cities to look for food. And on the other hand, bear populations may disappear completely from some areas: “Research we’ve done with the Hudson’s Bay population suggests very clearly that we likely will not have polar bears in that area by mid-century.” It’s a sobering prediction, and another reminder of the importance of fighting to combat climate change, for ourselves and for the other creatures we share this country with.
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