Charismatic bears on thin ice

"Polar bears have been known to live as long as 30 years.... That means today's young bears may be part of the last generation in Alaska. While older bears will probably scrape along, scientists expect to see cubs and young adults die off and reproduction rates decline. Already, studies have reported shrinking weight and rising mortality of cubs. There have also been reports of polar bears drowning."

Among those who track ice patterns in the polar regions, there seems to be little doubt that climate-changing greenhouse gases are playing an important part in current trends, particularly since the world's oceans absorb much of the additional heat down to depths of several hundred feet. Dr. Serreze, the Arctic specialist at the US National Snow and Ice Data Center, told the British newspaper The Guardian:

"It seems that the Arctic is going to be a very different place within our lifetimes, and certainly within our children's lifetimes."

Sea ice usually melts in the Arctic summer and freezes again in the winter, the article says. But this year is different. "This summer we've got all this open water and added heat going into the ocean. That is going to make it much harder for the ice to grow back," Serreze told The Guardian. Wind and ocean circulation patterns can play a part in reducing sea ice, but the main culprit is man-made global warming, he says. "The rules are starting to change, and what's changing the rules is the input of greenhouse gases."

Meanwhile, scientists now suspect that global warming may have caused the population of gray whales in the Pacific to decline due to changing conditions in their feeding grounds, reports National Geographic News. It quotes Phillip Clapham, who works at the Alaska Fisheries Science Center, part of the National Oceanic and Atmospheric Administration's National Marine Mammal Laboratory in Seattle as saying:

"It's clear that future climate change will significantly impact the Arctic and sub-Arctic ecosystems on which gray whales and other species depend.... But quite how that colossal unintentional experiment comes out is anyone's guess."

Last year, National Geographic News reported that "The north Bering Sea, one of the world's richest feeding grounds ... is warming to the point where animals are being forced to adapt or suffer the consequences."

"Some animals, like gray whales, are moving farther north to follow the cold water. Meanwhile, pink salmon and pollock, fish typically found in the southeast Bering Sea, are moving into northern waters. Other animals of the north Bering Sea may not be adapting enough to survive. Bearded seals and walruses, which feast on ... bottom-dwellers, are struggling with a reduced food source."

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