How Have the Polar Regions Changed?
Measurements on land and ocean show that the average temperature of the Earth’s surface increased during the 20th century. From 1975 to 2005 the change is estimated to be more than +0.5ºC. The popular name for this change is “Global Warming”. During this same time period the Arctic changed as well – the extent and thickness of Arctic sea-ice declined, the mass of Arctic glaciers decreased, average surface temperature rose over vast expanses of Alaska, Canada and Siberia, shrubs began to replace tundra plants, permafrost soils warmed, stellar sea lion population declined steeply in the Bering Sea, and the size of Caribou herds in Alaska and Canada fluctuated by more than 50%. People living in the Arctic have been affected by these and other long-term changes. For example, reduced sea-ice cover hastens erosion along coastlines and increases the danger and difficulty of traveling and hunting on the ice. Buildings, roads and other infrastructure constructed on permafrost soil are subject t
