This is an archived article that was published on sltrib.com in 2011, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.
Anchorage, Alaska • The surface area of sea ice in the Arctic Ocean shrank this winter to one of its lowest levels in decades — more bad news for polar bears, which depend on the ice to survive.
Since the National Snow and Ice Data Center in Boulder, Colo., began tracking sea ice three decades ago, only in 2006 was there as little ice during a Northern Hemisphere winter — 5.65 million square miles.
That's nearly 8 percent less than the average of 6.12 million square miles recorded from 1979 to 2000.
The expanse of polar ice reached its maximum on March 7, according to the center. The date of maximum ice in the studies has ranged from Feb. 18 to March 31. As of March 22, the ice had declined for five consecutive days, leading scientists to conclude it will only shrink further. However, scientists said, sea ice responds rapidly to winds and temperature this time of year and could expand again.
Steven Armstrup, senior scientist for the nonprofit Polar Bears International, said 2010 was one of the warmest years on record and that last autumn's ocean circulation patterns led to late and weak ice formation throughout much of the Arctic.
"This combination may [mean] early ice melt this year and large retreats of sea ice from polar basin coastlines," Armstrup said.
Eight months ago, Armstrup retired after 30 years as leader of polar-bear research at the U.S. Geological Survey's Alaska Science Center. He has studied Beaufort Sea polar bears since 1980 and is past chairman of the International Union for Conservation of Nature.
"Because polar bears depend on the surface of the sea ice to catch seals, those things are not favorable for polar-bear survival. So, if you are a polar bear, this could be a tough year — with increased starvation, especially among the young and very old."
But Armstrup is far less concerned with what happens in 2011 or any individual year than he is with rising average temperatures in the Arctic.
"The world will continue to warm, as greenhouse gas concentrations rise," he said.