The photographer who captured a now-viral video of an emaciated polar bear in northern Canada said Thursday that the animal is not necessarily a victim of climate change, but is a sign of things to come if global temperatures continue to rise.
Those points were echoed by two longtime polar bear researchers, including one who said some polar bears starve because they're poor hunters.
The heart-wrenching footage of the extremely thin bear, dragging itself across the eastern edge of Somerset Island and scrounging hopelessly for food on land, has rocketed across the internet in recent days, sparking a debate on whether its gaunt condition should be blamed on climate change.
Paul Nicklen, co-founder of the SeaLegacy conservation group on Vancouver Island in Canada, said his group used the phrase "the face of climate change" when posting images of the bear on its Web page and on social media.
But the group also said it did not know why the bear was starving.
In an interview Thursday, Nicklen said he filmed the bear for about three hours in August before it walked to the ocean and swam away. He said he doesn't know whether the bear's emaciation was tied to illness, injury or some other factor.
He said the bottom line is that scientists fear the world's population of about 25,000 polar bears will drop significantly in the coming decades, and the animal could disappear in the next century because of climate change.
"These (images) aren't data points on a paper," he said. "This is what a bear looks like when it starves."
Steve Amstrup, the former director of polar bear research in Alaska at the U.S. Geological Survey, said Wednesday the exact cause of the polar bear's severely malnourished condition can't be determined.
But that's beside the point, said Amstrup, now with Polar Bears International, a conservation group.
"It would be incorrect to say this bear is clearly being killed by global warming or climate change," said Amstrup.
It's possible the bear is simply a poor hunter, Amstrup said. He witnessed that exact situation in the 1980s during an autumn research season in northern Alaska.
A young polar bear he saw then was in the same physical condition as the Somerset Island bear, hardly able to move and weighing a fraction of what it should. The bear Amstrup saw had apparently not learned the hunting skills it needed, he said.
"These kinds of things have happened," he said. "But organizations that would like to deny climate change, this is one thing they point out. They say, 'Oh, this happened in the past, so it's no big deal.' The big deal is this is a warning to us of the kind of thing that will become more frequent in the future."
Increases in carbon emissions and greenhouse gasses are directly linked to a warming planet and melting sea ice, he said.
Shrinking sea ice in recent years has reduced the hunting grounds where bears pursue their main prey, seals. They've been forced to spend more time on land, hunting less energy-rich meals that can range from rodents to caribou. If they're lucky, they might find whale carcasses left by Alaska Native subsistence hunters.
"When you take the ice away, you're basically taking away their dinner table," said Amstrup.
USGS officials involved in polar bear research could not be reached.
Geoff York, who also worked many years as a USGS polar bear scientist in Alaska, now works for Polar Bears International with Amstrup.
From the video, it's hard to tell the polar bear's age, said York. The face of a dominant older male would often be scarred from years of brawls, and this bear lacks those signs.
That doesn't mean it's a young bear, he said.
The video is a sad thing to witness, York said. But this could simply be an "old, injured, or sick bear struggling to survive."
"But is that bear consistent with what we expect as the Arctic warms? Sure," he said.
York said he didn't have much hope the bear is still alive, because it was in such poor condition.
But polar bears can be remarkably resilient.
About a decade ago, he captured a bear as skinny as the one in the video, though it didn't appear as close to death, he said.
"It was literally one or two seals away from making it," York said. "But it got lucky."
Scientists caught the same bear two years later, this time doing fine.
"Polar bears have an incredible physical resilience to go from very thin to very fat, to make that shift, so it can be difficult to look at a bear and say it's a goner," he said.
The polar bear population in the Baffin Bay region, east of where Nicklen filmed the bear, is considered stable, York said. But its long-term outlook isn't good as sea ice continues to melt.
Some polar bear populations are struggling, including in the southern Beaufort Sea region that includes part of northern Alaska.
About 15 years ago, while working for the USGS in that region, York began to see unusual signs that polar bears weren't doing well. Some bears had died inexplicably in their prime. He wasn't seeing younger bears, and many bears were thinner.
In 2014, scientists reported that southern Beaufort Sea polar bear numbers plunged 40 percent during this century's first decade.
Meanwhile, the Chukchi Sea population, whose range includes northwestern Alaska, appears to be holding steady, though "unprecedented" ice loss increasingly puts the fate of those bears in question, York said.
Nicklen, with SeaLegacy, said he's pleased the video has drawn so much interest.
"I'm trying to break down the walls of apathy and spark a global debate," he said. "I think this is doing that."