We recently heard of the
polar bears drowning 60 miles out to sea. Polar bears can actually swim 60 miles (!) but if there's nothing there when they arrive, of course they're too exhausted to either turn back or continue. Global warming is causing the sea ice to recede. It used to be only about 20 miles from shore, so the polar bears could swim easily. Now it's 60 miles or more, too far for some bears to make. There's also speculation that the long swim leaves them vulnerable to rough seas.
The researchers were startled to find bears having to swim up to 60 miles across open sea to find food. They are being forced into the long voyages because the ice floes from which they feed are melting, becoming smaller and drifting farther apart.
SNIP
According to the new research, four bear carcases (sic) were found floating in one month in a single patch of sea off the north coast of Alaska, where average summer temperatures have increased by 2-3C degrees since 1950s.
Apparently
this is happening to seals as well, which also rely on the sea ice. The seals are a primary food source for the polar bears, which explains why they're so willing to swim as far as they do.
In addition to the slaughter by Maritime sealers, seal pups have been washing on shores, dead, presumably from drowning. Pups only learn to swim weeks after they are born, so they depend on good ice conditions; but this year, the ice conditions were the worst in recorded history.
Apparently, though, it's even worse than that. The polar bears, unable to reach or find their usual food sources, have turned to eating each other.
The study reviewed three examples of polar bears preying on each other from January to April 2004 north of Alaska and western Canada, including the first-ever reported killing of a female in a den shortly after it gave birth.
SNIP
"During 24 years of research on polar bears in the southern Beaufort Sea region of northern Alaska and 34 years in northwestern Canada, we have not seen other incidents of polar bears stalking, killing, and eating other polar bears," the scientists said.
SNIP
Cannibalism demonstrates the effect on bears, said Kassie Siegal, lead author of the petition.
"It's very important new information," she said. "It shows in a really graphic way how severe the problem of global warming is for polar bears."
Deborah Williams of Alaska Conservation Solutions, a group aimed at pursuing solutions for climate change, said the study represents the "bloody fingerprints" of global warming.
(Emphasis mine.) So, what we've got here is 34 years of no (zero) incidents of polar bear on polar bear predation, then 3 (known) incidents in the last year or so. Let us hope that humans are not forced by global warming upon the same path.