Blocks of frozen ground, known as permafrost, break off into the ocean as the ground thaws along coast of Canada
Natural Resources Canada, Earth Sciences Sector
The Warming Arctic
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 of frozen ground, called permafrost, is releasing methane, a greenhouse gas, into the atmosphere and is causing damage to buildings and roads. Along the coast, thawing permafrost is causing shoreline sediments to slump into the seawater, like in the picture at the left.
There have been noticeable changes in plant and animals populations in the Arctic too. 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. Peary caribou in northern Canada have declined from 24000 in 1961 to perhaps as few as 1100 in 1997 because there have been years where 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.
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