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Reports: global warming
may be pushing polar bears to drowning, cannibalism
Dec. 22,
2005
Special to World Science
Global warming may be forcing polar bears into cannibalism and suicidal swims as the temperature change melts away their home, some researchers claim.
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Courtesy U.S. National Institutes of Health
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The reports, described in a news story this week’s issue of the research journal
Nature, are unproven, the article said. “Experts say it is too early to be sure, but that these are the kind of impacts expected as melting sea ice leaves the bears with longer distances to travel,” the report added.
Some of the reports came from a biennial conference on the biology of sea mammals in San Diego, California, last week, the
article said.
At the meeting, marine biologists from the U.S. Minerals Management Service reported finding four bears drowned off the northern coast of Alaska last autumn, according to
Nature.
They also spotted an unusually large number of bears swimming in the open sea, some as far as 95 kilometres offshore, the report claimed—types of swim for which they’re poorly adapted.
Twenty percent of bears seen in the area in September were in the water,
Nature cited the scientists saying, while records from previous years show that 4 percnet of sighted bears were swimming.
Tonje Folkestad, climate-change officer at the World Wildlife Fund’s Arctic programme in Oslo, Norway, told
Nature that “We can’t say at the moment that there is a trend for polar bears to drown… But we do expect to see more of this kind of event in the future.”
Spending more time in the open sea increases bears’ exposure to the risks of the effect of cold, exhaustion or rough seas. “Common sense tells you that if they have to swim 60 miles instead of 20, drowning is more likely,” Folkestad told the journal.
Folkestad added that melting Arctic ice, the main habitat for polar bears, presents major problems for them. The Arctic ice sheet is shrinking at a about
10 percent per decade, with Arctic summer temperatures climbing to around 2
degrees Celsius higher than they were 50 years ago. About 1.3 million square kilometres, an area equivalent to three times that of California, have been lost over the past four years.
Rangers in Yakutia, northeastern Russia, saw two incidents of one bear killing another, with some media reports claiming that starving bears were practicing
“cannibalism,”
Nature noted.
“These observations are not rare or extraordinary in themselves,” Folkestad told Nature. “What was unusual was the lack of sea ice in the area.”
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