Even more important, Michael Wolfe says that listing the polar bear could prove to be a watershed event in rousing politicians and the public toward addressing the challenges posed by climate change.

Wolfe, a professor of wildlife ecology and management at USU, says he was surprised, bordering on dumbfounded, when Interior Secretary Dirk Kempthorne last month announced that, following two years of review, the U.S. Fish and Wildlife Service would propose listing the polar bear as a threatened species under the Endangered Species Act.

"It's certainly warranted," Wolfe said last week. "And knowing the administration's stance on global warming, I was very surprised. It seemed curious.

"But if you look at the importance of sea ice to polar bear biology and the fact that there has now been such a significant shrinkage of sea ice, that's pretty difficult to ignore. At the very least, it's a tacit admission that, yeah, global warming is upon us and that it is having a very real impact on wildlife."

And the polar bear, what Wolfe jokingly calls "a charismatic megavertabrate," might be just the species to accelerate the pace of the climate change debate.

"We've got three or four calendars throughout our house, and every one of them has a polar bear photo of some kind," he said. "This is a warm and fuzzy animal [in the public consciousness]. If it makes people think about the link to global warming and its impact on our biology, that's all good."

But Wolfe, who specializes in the research of large predators, most notably cougars, cautions that even with raised public awareness, the polar bear's plight is complex. And its prognosis will depend on many factors.

News media reports of polar bear drownings because of shrinking sea ice - and the longer distances the bears must now swim - are largely overhyped, though it certainly happens, he said. The real problem posed by such circumstances lie in the long-term toll they take on the species.

"As the open water increases, transit times [between ice floes] and the amount of travel will increase, and food resources are likely to decline," Wolfe noted. "The consequences of the increased energy polar bears must use to cover those distances are reduced weight and reproduction."

The sea ice is most vital for putting polar bears in striking distance of their primary prey - seals. Wolfe says researchers are unsure to what extent hunting opportunities have declined because of shrinking sea ice, but it likely has had an impact.

Sea ice also plays a role in cub mortality, he says. Polar bear offspring are poorly developed at birth, and are largely shielded by their mothers, who tunnel into deep snow, until they are prepared to get out and move around, and swim and access prey.

"If you have some deterioration of these areas, they may be leaving the tunnels earlier, and the young may not be able to cope with the arctic winter," Wolfe said.

As the bears are pushed closer to shore, they may also collide with other large predators, such as wolves, who would prey on polar bear cubs and compete with adult bears for other prey. Wolfe also believes such a shift closer to land would subject the bears to a possible collision with energy development in the arctic.

These aren't just theories, either. Long-term surveys of the species in Canada's western Hudson Bay show reduced weights and increased cub mortality, leading to a 22 percent decline in the population, correlated with the loss of sea ice. Detailed studies of other polar bear populations are currently unavailable, but the Fish and Wildlife Service says they likely face a similar situation.

If the problems facing the polar bear are complicated, so are the solutions. The reality is, the United States can lay claim to only a small portion of the overall polar bear population, estimated at between 20,000-25,000. Within Alaska there are roughly 4,700 bears that the U.S. shares with Canada and Russia. Any effort to protect the bears globally will have to be coordinated globally.

"I don't think there are any engineering fixes here," Wolfe said. "If we're going to fix this, we're going to have to fix the habitat. Things like ending hunting, reducing contaminants such as PCBs, which works its way up the food chain to the top predators.

"We need international agreements for all that stuff," he added. "But I'm not even sure that will fix the problem if we don't start to turn the climate problem around."

jbaird@sltrib.com