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December 1st, 2009

Portions of Arctic coastline eroding, no end in sight

Irina Overeem stands on the rapidly eroding coastline near Drew Point, northern Alaska. Photo by Robert Anderson.

Robert Anderson, Irina Overeem, Gary Clow, and colleagues have found that the northern coastline of Alaska midway between Point Barrow and Prudhoe Bay is eroding by 30 to 45 feet a year because of a "triple whammy" of declining sea ice, warming seawater and increased wave activity. The 12-foot-high bluffs in this region consist of frozen blocks of silt and peat containing 50 to 80 percent ice. During the summer months, the bluffs topple into the Beaufort Sea as waves deliver warm seawater to melt a notch that undermines their base. Once the blocks have fallen, the coastal seawater melts them in a matter of days, sweeping the silty material out to sea. The team monitored the dynamic transition between the land and the sea through the use of time-lapse photography of shoreline erosion, global positioning system mapping (GPS), meteorological measurements including temperature and wind speed, and sediment analyses of the coastal bluffs. Offshore measurements included sea-ice distribution, ocean floor depth, sea-surface temperatures and wave dynamics. While there are no towns adjacent to the specific study area, coastal erosion threatens abandoned military and petroleum infrastructure nearby and occurs at similar sites elsewhere along Alaska's coastline. Bank stabilization measures using sandbags, for example, have been undertaken at the Alaskan town of Kaktovik on the Beaufort Sea in an attempt to slow the erosion.

See the links to the right to view a video featuring Anderson and time-lapse photography of the eroding coastline. The team's results were presented in a series of talks and posters at the annual meeting of the American Geophysical Union in San Francisco held Dec. 14-18. Anderson also presented the research findings at a news conference addressing the impact of climate change on the Arctic.

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