- ?Lv 61 十年 前最佳解答
The U.S. Geological Survey predicts two-thirds of the world's polar bears will disappear by 2050, based on moderate projections for the shrinking of summer sea ice caused by global warming. The bears would disappear from Europe, Asia, and Alaska, and be depleted from the Arctic archipelago of Canada and areas off the northern Greenland coast. By 2080, they would disappear from Greenland entirely and from the northern Canadian coast, leaving only dwindling numbers in the interior Arctic archipelago.
Predictions vary on the extent to which polar bears could adapt to climate change by switching to terrestrial food sources. Mitchell Taylor, the director of Wildlife Research for the Government of Nunavut, wrote to the US Fish and Wildlife Service arguing that local studies are insufficient evidence for global protection at this time. The letter stated, "At present, the polar bear is one of the best managed of the large Arctic mammals. If all Arctic nations continue to abide by the terms and intent of the Polar Bear Agreement, the future of polar bears is secure.... Clearly polar bears can adapt to climate change. They have evolved and perisisted for thousands of years in a period characterized by fluctuating climate." Ken Taylor, deputy commissioner for the Alaska Department of Fish and Game, has said, "I wouldn't be surprised if polar bears learned to feed on spawning salmon like grizzly bears."
However, many scientists consider these theories to be naive; it is noted that black and brown bears at high latitudes are smaller than elsewhere, because of the scarcity of terrestrial food resources. An additional risk to the species is that if individuals spend more time on land, they will hybridize with brown or grizzly bears.
2009-05-24 10:23:37 補充：
The global polar bear population, estimated to be 22,000-25,000 bears, is relatively stable. However, in 2006, the World Conservation Union upgraded the polar bear from a species of Least Concern to a vulnerable species.
- 此生不換Lv 71 十年 前
Climate change to force the Food and fewer polar bears kill each other
(AFP) March 19, 2009 Thursday, 15:05
(Agence France-Presse, Norway特隆索19) may result in the death of polar bear global warming has left marks of this species, the polar bear has become relatively small size and activity have become smaller, and the case of cannibalism have getting more and more serious.
The world's leading experts in this week's特隆索in the northern part of Norway to discuss ways to protect the polar bear and warned that melting Arctic ice and snow caused serious consequences.
International research network "type of expert group of Bear" (Bear SpecialistGroup) trapeang but President (Andrew Derocher) said: "We have no evidence of climate change, but we can prove that climate change caused by the polar bears many signs of him."
First observed when the sea ice melt sales, polar bears are smaller than their size has been the past.
Large polar bear population live in the Hudson Bay in Canada (Hudson Bay) ice season shorter than 30 years ago, three weeks, deprived of food polar bears hunting seals opportunities. Seals is that they spend a long summer of famine in the basic source of fat.
Today's mother polar bear weighing about 230 kilograms more than the standard 1980 light 65 kg, an average of about 185 cm in length, compared to a few decades ago, when the mother bear is about 220 cm.
Melting ice and snow mean that polar bears need to go further, to reach the hunting ground, where cold temperatures enough to be prey.
Experts warned that this variation so that the polar bear health, affect their ability to bear children, and the Cubs chances of survival.
The impact of climate change also appears to the behavior patterns of polar bears.
Occurred recently in a number of Alaska polar bears eat a similar case, the experts worried.