Climate Change in Alaska
Climate change in Alaska: The state of Alaska is experiencing some of the most profound climate change impacts now occurring in the nation. Permafrost thawing is causing the ground to subside 16-33 feet in parts of interior Alaska, and the permafrost surface has warmed by about 3.5 oF since the 1960s. Summer days without snow have increased from fewer than 80 in the 1950s to more than 100 in the 1990s. Sea-ice extent has shrunk by about 5% over the past 40 years, and the area covered by sea ice declined by about 6% from 1978 to 1995. A study of 67 glaciers shows that between the mid-1950s and mid-1990s the glaciers thinned by an average of about 1.6 feet per year, and the rate of thinning had increased to nearly 6 feet more recently. The state’s annual average temperatures have warmed up to 1.8 oF per decade over the last three decades, and winter warming has been as high as 3 oF per decade. The consequences of global warming for wildlife species will be severe. An example is the polar bear, which has been placed on the U.S. Endangered Species List. It has been designated by the U.S. Interior Department as “threatened with extinction because of shrinking sea ice”, making it the first creature added to the endangered species list primarily because of global warming. Experts say that two-thirds of the polar bear’s habitat may disappear by 2050. Polar bears are dependent on hunting ringed seals and other prey from sea ice. They are so unsuccessful on land that they spend their summers fasting, losing more than 2 pounds a day. This “forced fast” is now about three weeks longer than it was 30 years ago. This gives the bears less time to hunt and build up the fat reserves they need to survive until ice re-forms in the fall and they can resume hunting. As bears have become thinner, the reproductive rates of females and survival rates of cubs have declined. As Arctic ice breaks up earlier and earlier, bears now come ashore roughly 22 lbs. lighter and in poorer condition. The bears’ reduced body condition can lead to lower reproduction rates, which in the long run could lead to local extinction.
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