14 DAY TRIAL // Currently, there are 20,000 to 25,000 polar bears world-wide. But more and more information gathers pointing to strong evidence that polar bear may face a bleak survival rate due to climate change.
Previous observations had showed that progressive earlier breakup of sea ice has decreased the chances of reproductive success for female polar bears in the past 20 years in the southern Arctic area and some think that polar bears could be extinct within the next century (see article bellow).
"These data provide evidence for a direct linkage between reduced sea ice coverage, presumably caused by climate change, and decreased polar bear survival in western Hudson Bay," said Eric Regehr a US Geological Survey (USGS) employee, who analyzed in the last two years polar bear data collected by the Canadian Wildlife Service in Canada's western Hudson Bay. The western Hudson Bay polar bear population decreased by 22 %, from 1,194 in 1987 to 935 in 2004. Only 43 % of polar bear cubs in the area survived their first year in 2004, compared to a 65 % survival rate in the 1980s and early 1990s.
Unlike Alaska's more northern sea ice environment, the sea ice in Hudson Bay melts completely for three to four months annually, and - during this time - the animals stay on shore relying on their own fat reserve.
Earlier melting of sea ice also explains why recently there has been an increase in human interactions with polar bears in settlements along the western shore of Hudson Bay, like in Churchill, Manitoba. "As polar bears become more nutritionally stressed due to changing sea-ice conditions, they have become more likely to come into town to look for food," Reger says.
Western Hudson Bay is the most southern area of polar bears' range. Findings in that region may foreshadow how more northern polar bear populations (specifically those in Alaska) could respond if the Arctic continues to warm.
The only polar bears on the US territory are found in Northern Alaska. In Alaska, scientists have found - for the first time - drowned polar bears, probably exhausted by far longer swimming distances (even if polar bears are capable of swimming up to 60 miles -100 km - without stopping) between ice caps.
The ice loss condemns polar bears to starvation, because they are adapted to hunt seals while on ice. Recent aerial surveys show that - in the last five years - polar bears have changed their behavior and spend more time on land, searching for whale carcasses on the beaches.
The last survey in 1997 suggested that polar bears were on a steady trend but the recent observations have found something else. U.S. conservation groups seek federal protections for the Alaska polar bears. "While the majority of Alaskan polar bears do not spend the summer on land or among human habitats, the recent trend toward a longer ice-free season off Alaska's northern coast has forced polar bears from the biologically-productive waters over the continental shelf to the deep, offshore regions where prey may be more limited," said George Durner, a PhD of UW, working with USGS.
"I think polar bears are in many ways very flexible in that they seem to adjust to certain conditions, but they can only do that to a certain point," Durner says.
"There may come a point where ice conditions change so much that polar bears will not be able to compensate, and we're going to see effects of nutritional stress in the population, represented in lower survival of certain age groups [juvenile, sub-adult, and aging adult], which ultimately would affect polar bear population status in Alaska."
Before protecting American polar bears under the Endangered Species Act, scientists must seek information regarding population distribution, habitat, and effects of global warming on both the polar bears and their prey, but also the potential effects of development, contamination, and poaching threats.