Study Reveals Shrinking Lakes & Melting Permafrost Spans Arctic Regions

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"As temperatures rise, ice and snow melt and put more water into Arctic lakes. Larry Smith, an associate geography professor at the University of California, Los Angeles, said researchers expected to measure more, larger lakes, not fewer. "We were expecting to see more of the same," he said. They now believe additional lake surface brought on by melting is just the first part of the process. In the southern parts of the Siberia study area, the permafrost itself is believed to be melting.

Researchers mapped four zones of varying amounts of permafrost. As they looked south, where permafrost thinned or disappeared, lakes were shrinking. That indicates melt water is seeping into soil as permafrost decreases, Smith said.

Larry Hinzman, a University of Alaska Fairbanks researcher, found a similar phenomenon at tundra ponds on Seward Peninsula near Council in western Alaska. Surface pond area there decreased over the last 50 years. "This is the first paper that demonstrates that the changes we are seeing in Alaskan lakes in response to a warming climate is also occurring in Siberia," Hinzman said.

The latest study was aimed at quantifying the Alaska observations on a larger basis, Smith said. Small, shallow tundra lakes that rest on permafrost are "ephemeral," coming and going with variations in weather, Smith said. Researchers instead studied lakes of 40 hectares or about 100 acres, Smith said. The study compared satellite digital images from 1973 with images from 1997-98. Researchers entered images into computers and "co-registered" them with modern data by manually picking control features -- structures that can be confidently identified in both photos, Smith said."

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http://www.adn.com/news/alaska/story/6579877p-6463350c.html