900 trillion gallons of water has been added to the oceans from melting glaciers over the last 50 years.

Alaska's glaciers are melting. A University of Alaska group has been keeping track of 100 representative glaciers by taking precise height measurements from a specially equipped light plane. They've found that glaciers have been thinning for 50 years, and the rate is increasing. Their surfaces now are dropping an average of 6 feet a year. One result is staggering volumes of water added to the oceans-900 trillion gallons in the last 50 years from Alaska and western Canada alone, raising sea levels by about a quarter of an inch worldwide.

Alaska's permafrost, which underlies 85 percent of the land, also is heating up. Alan is shown boreholes sunk into the permafrost that are registering temperatures a fraction of a degree away from thawing, and he visits the Tanana River flats where collapsing "drunken forests" indicate that the underlying permafrost is already breaking up.

Certain insect pests thrive in warmer climates and are threatening to kill Alaska's vast boreal forests.

Everywhere, Alaska is getting warmer and dryer. Researchers analyzing satellite photographs have found that the state has lost 15 percent of its lake and pond area during the last 50 years. Forest scientist Glenn Juday shows Alan the insect pests that are thriving in the new warm conditions, and predicts that if present trends continue Alaska's vast boreal forest simply "won't be able to grow."

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After the Science -- Public Policy Actions