In this video segment, a team of scientists seeks evidence to support their hypothesis that atmospheric warming -- either now or in the past -- may explain why water has formed beneath the West Antarctic ice sheet, causing ice streams that flow much more quickly than the rest of the ice sheet. This phenomenon has important implications for potential sea level rise.

A collection of repeat photography of glaciers from the National Snow and Ice Data Center (NSIDC). The photos are taken years apart at or near the same location, illustrating how dramatically glacier positions can change even over a relatively short period in geological time: 60 to 100 years. Background essay and discussion questions are included.

In this audio slideshow, an ecologist from the University of Florida describes the radiocarbon dating technique that scientists use to determine the amount of carbon within the permafrost of the Arctic tundra. Understanding the rate of carbon released as permafrost thaws is necessary to understand how this positive feedback mechanism is contributing to climate change that may further increase global surface temperatures.

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