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Alaska coast erosion threat to oil, wildlife

ANCHORAGE, Alaska, Dec 21 (Reuters) - A portion of Alaska’s North Slope coastline is eroding at a rate of up to 45 feet (14 meters) a year, posing a threat to oil operations and wildlife in the area, according to a new report issued by scientists at the University of Colorado.

Warmer ocean water has thawed the base of frozen bluffs and destroyed natural ice barriers protecting the coast, causing large earth chunks to fall each summer, the scientists said.

“What we are seeing now is a triple whammy effect,” study co-author Robert Anderson, an associate professor at the University of Colorado’s Department of Geological Sciences, said. “Since the summer Arctic sea ice cover continues to decline and Arctic air and sea temperatures continue to rise, we really don’t see any prospect for this process ending.”

The scientists studied coastline midway between Point Barrow, the nation's northernmost spot, and Prudhoe Bay, site of the nation's biggest oil fields. The erosion, if it continues, could ultimately be a problem for energy companies such as Exxon Mobil Corp XOM.N and BP Plc BP.L.

Findings were presented last week at the annual meeting of the American Geophysical Union in San Francisco. They backed up other studies of erosion along Alaska’s Beaufort Sea coastline.

A study by U.S. Geological Survey scientists published in February found that erosion along a stretch of Alaska coastline during 2002 to 2007 was twice as fast as in the period from 1955 to 1979. That USGS study also found erosion occurring at a rate of 13.6 meters (44.6 feet) annually from 2002 to 2007.

The three-year University of Colorado study aimed to examine how erosion is occurring, said co-author Irina Overeem, a scientist at the University’s Institute of Arctic and Alpine Research.

The scientists employed time-lapse photography, global positioning systems, meteorological monitoring, and analysis of sediment and sea-ice distribution.

Photographic images snapped every six hours during the around-the-clock sunlight of summer were particularly dramatic, Overeem told Reuters.

“There’s a notching effect that just notches, notches, notches and then topples over,” she said. “The cliffs are more than half ice -- they’re basically dirty icebergs -- so warm water, stronger waves and higher wave action quickly carves them away,” she said.

Although the study area holds no communities, there is infrastructure at risk, mostly abandoned military and oil-field sites and their associated waste dumps, the scientists said. Also at risk are ponds and lakes that support migratory shorebirds.

The threat of collapsing military and oil-field infrastructure, including toxics-laden waste, has prompted several government agencies to launch emergency cleanup programs.

The U.S. Bureau of Land Management since 2005 has cleaned up three old, erosion-threatened wells and plans to start in on a fourth well later this winter, said Wayne Svejnoha, branch chief for energy and minerals. Each well cleanup takes about two months and costs $12 million to $14 million, Svejnoha said.

Erosion threats to shorebirds were confirmed by another federal manager.

“The erosion is very obvious,” said Rick Lanctot, Alaska shorebird coordinator for the U.S. Fish and Wildlife Service. In some spots, saltwater has inundated lakes and ponds, killing off plants that birds eat, while heavy wave action has displaced driftwood used as nest sites, said Lanctot, who has worked there since 1991. (Reporting by Yereth Rosen; editing by Bill Rigby, Gary Hill)