The sea has pushed in half a mile (0.9 km) in some places over past decades, the study said.

"Since beaches are absent or poorly developed along most of the studied coast, there is little, if any, protection against this increased wave energy. As a result, the waves undercut the mud-rich permafrost land, causing it to collapse into the sea," said USGS scientist John Mars in a statement released by the agency.

In addition, salty sea water has contaminated formerly freshwater lakes, migratory birds, caribou and other wildlife populations has lost habitat and the sparse human infrastructure along the coastline has been damaged, the study said.

The study is in the current issue of Geology, a periodical of the Geological Society of America.

Global warming has been pronounced in Alaska and other parts of the Arctic, with average winter temperatures rising as much as 5.4 to 7.2 degrees Fahrenheit (3 degrees or 4 degrees Celsius) over the last six decades, according to the international Arctic Climate Impact Assessment.

"The area (Teshekpuk Lake) is one of the most important areas in the entire Arctic, and I don't just mean in Arctic Alaska," said Stan Senner, executive director of Audubon Alaska. "It is simply the most important goose-molting area in the Arctic."

It is also believed to hold vast amounts of untapped oil. In recent years, the Bush administration lifted a decades-long ban on oil development and has tried to sell oil and gas exploration rights there.