As Arctic sea ice flirts with its lowest levels in recorded history, polar scientists are taking the opportunity to remind us that it isn't just humans who are screwed because of melting ice caps. Remember polar bears, global warming's first darling poster child? They're still around, and they're not happy with what we've done to the planet. A polar bear testing thin ice with its paw. Image: Mario Hoppmann
Across the Arctic, 19 separate polar bear subpopulations head out onto the ice in the winter and spring to hunt seals, their main source of kilojoules. All 19 groups have seen hunting season dramatically shortened because of climate change. That's according to a new analysis published today in The Cryosphere, which drew on 35 years of satellite data to show that dwindling sea ice is bringing an earlier spring thaw and later autumn freeze-up to all regions of the Arctic inhabited by polar bears.
Arctic sea ice levels in 2016 (red) and the record low year of 2012 (green), compared with the long-term average (black). Image: NSDIC
On average, the researchers found that in polar bear-populated regions, spring ice melt has been starting three to nine days earlier per decade since 1979, while autumn freeze up has been arriving three to nine days later. Over 35 years, this amounts to a reduction in hunting season of up to seven weeks, which is a lot of time that mamma bears could be packing on the seal blubber and feeding it to their young.
"These spring and fall transitions bound the period when there is good ice habitat available for bears to feed," study co-author Kristin Laidre, a researcher at the University of Washington's Polar Science Center said in a statement. "Those periods are also tied to the breeding season when bears find mates, and when females come out of their maternity dens with very small cubs and haven't eaten for months."
At the rate sea ice is dwindling, the researchers say that polar bears can expect to see their hunting season reduced by another six to seven weeks by mid-century. This, of course, will leave the enormous Arctic predators with one option: Terrorising the very scientists who want to save them. So unless we're willing to let human-polar bear relations descend into chaos, we might want to do something about all that carbon being added to the atmosphere.