Natural Resources Canada, Earth Sciences Sector
In the north polar region, the climate has warmed rapidly during the past few decades. Average temperatures in the Arctic are rising twice as fast as they are elsewhere in the world. In Alaska (USA) temperatures have increased on average 3.0°C (5.4°F) between 1970 and 2000.
The Arctic is showing some of the most dramatic effects of global warming. Glaciers, including parts of Greenland’s massive ice sheet, are melting rapidly. Sea ice covers less of the Arctic Ocean each summer. Snow blankets some areas for less of the year. Thawing permafrost releases methane, a greenhouse gas, into the atmosphere. It is also causing damage to buildings and roads. Along the coast, thawing permafrost is causing erosion, like in the picture at the left.
The numbers and species of plants and animals are also changing. Some species are moving further north to be where it is cooler. For example, there are more shrubs growing in the tundra of Alaska and trees are able to grow further north. Other species have experienced population booms or declines. There used to be 24,000 Peary caribou in northern Canada in 1961. But 1997 there were only about 1100 caribou. Many could not survive because were times when food was limited. Polar bear populations may be declining because melting sea ice limits their hunting opportunities. Meanwhile, in Alaska, spruce bark beetles are breeding faster than ever in the warmer climate. From 1993 to 2003 the oversized beetle population chewed up 3.4 million acres of forest trees.
source: windows to the universe