A new U.S. study of polar bears off Alaska’s coasts says faster-moving sea ice brought on by rapid global warming is adding to the animals’ physiological stress.
Research ecologist George Durner said that adds to problems for polar bears in the southern Beaufort Sea.
“Polar bears in those regions largely stay within those subpopulation areas throughout their lives,” Durner said. “But to do that they can’t just sit still. If they want to stay within their subpopulation bounds, they constantly have to be moving east all the time. And so yes, it essentially is a treadmill.”
The study by U.S. Geological Survey researchers and others said the already at-risk bears have to burn more calories to stay within their preferred habitat as sea ice drifts. Researchers have documented declining body condition, reproduction and survival among polar bears as diminished sea ice gives them fewer opportunities to hunt for seals.
The study contains two data sets ranging from 1987 to 1998 and 1999 to 2013. When asked what the most significant changes have been in the polar bears over that span of time, Durner pointed to the survival rate of young bears.
“Steve Amstrup and I did a survival study that was published back in 1995. In that study we determined that first year survival of young was around 65%,” he said. “In the most recent work that was done by Jeff Bromaghin and others including, I was a coauthor on that work as well, first year survival dropped down to I believe it was 40%.”
According to Durner, polar bears may disappear from Alaska by mid-century as sea ice continues to melt. However, as long as Alaskan sea ice reforms each winter, Canadian polar bears may enter the region on a seasonal basis.
Durner said that polar bear research will be refined as resources become available and that he hopes this study will influence arctic conservation policy.
Lori Townsend is the chief editor, senior vice president of journalism and senior host for Alaska Public Media. You can send her news tips and program ideas for Talk of Alaska and Alaska Insight at ltownsend@alaskapublic.org or call 907-550-8452. Read more about Lori here.
