Polar bears threatened by global warning - experts
Date: 20-May-02
Country: USA
Author: Will Dunham
So why are conservationists sounding the alarm about the fate of the world's largest land carnivores?
They say there is mounting evidence that warming temperatures in polar regions could obliterate the bears' delicate frozen habitat in the coming decades. Many scientists blame the warmer temperatures on human activities far removed from the Arctic.
In particular, conservationists say, global warming could deprive the bears of the vast expanses of Arctic sea ice where they prowl for prey such as seals.
World Wildlife Fund climate scientist Lara Hansen, whose organization last week released a report on the peril faced by polar bears, said it is vital for people to start taking the threat seriously.
"Although the conservation status of polar bears is 'not currently in danger,' this is the time to start thinking about the conservation of polar bears," Hansen said.
"Primarily people don't start thinking about the conservation of a species until there are 500 of them left," Hansen added. "In the case of polar bears, we have a tremendous advantage in that we can see a problem starting, we can take action on it now, and we could potentially be doing something to protect polar bears before their numbers and their habitat are so lost that nothing can be done."
Ian Stirling, an expert on polar bears, said while the threat is a long-term one, there are early signs of trouble in the southern portion of the polar bear's range.
TOP OF THE FOOD CHAIN
"What really is important about polar bears surviving is that they are the top animal in the Arctic marine ecosystem," said Stirling, a research scientist with the Canadian Wildlife Service. "A healthy population of polar bears probably tells you that the ecosystem as a whole is pretty healthy."
Experts say there are between 22,000 and 27,000 bears in the world, divided among 20 populations varying in size from a few hundred to a few thousand in Alaska, Canada, Russia, Norway and Greenland. Sixty percent of the bears live in Canada.
They are found throughout most of their original range, and in numbers similar to those before the industrialized era. Most of the original habitat of the polar bear remains intact - and not inhabited by humans. But people do not have to live on the next iceberg to cause trouble.
Many scientists believe the burning of some fuels releases carbon dioxide and other gases into the atmosphere, trapping heat and triggering global warming, the so-called greenhouse effect. Many scientists believe the effect will be felt most acutely in polar regions.
The World Wildlife Fund report said Arctic temperatures have been rising over the past century, and the presence of sea ice has fallen.
BAD NEWS, BEARS
That's bad news for the bears. Polar bears spend months at a time roaming the frozen surface of Arctic seas in search of prey, particularly ringed seals and bearded seals, as well as young walruses, beluga whales, fish and seabirds. They eat as much as possible in order to store up fat reserves vital for surviving the ice-free summer months.
When the sea ice melts heading into summer, the polar bears are left without their hunting grounds. During this time, polar bears fast and enter a hibernation-like state.
The World Wildlife Fund report said that by 2050, the ice-free period during the summer will grow from 60 days to 150 days. That means a shorter feeding period for the bears.
Stefan Norris, head of conservation for the World Wildlife Fund's International Arctic Program in Norway and lead author of the report, said climate change already is affecting the body condition of bears in the southern range of their distribution - Canada's Hudson Bay and James Bay. When sea ice melts earlier in the spring, polar bears are forced to move to land with smaller fat reserves to ride out the summer, he said.
With reproductive success tied closely to body condition, he said those polar bears likely will be grossly reduced in number, and "
