Tuesday, February 24, 2009

Alaska Coasts Melting -- And Not Just the Ice

Rebecca Carroll
for National Geographic News

Part of Alaska's coast is drifting into the sea at twice the rate it has in the past, reshaping the Arctic shoreline, a new study says. The trend could seriously threaten the area's caribou and other wildlife, as well as local landmarks that document human settlements.

Some stretches of the state's northern shore along the Beaufort Sea receded by more than 80 feet (25 meters) in summer 2007 alone, when Arctic sea ice was at a record low.

In the past, spurts of erosion had often been linked to storms, but there were no major storms in 2007. That suggests "a shift in the forces driving erosion," said lead author Benjamin Jones, a research geographer at the U.S. Geological Survey.

One major force now is global warming, according to the research.

The study of the 40-mile (64-kilometer) stretch of coast was published this week in the journal Geophysical Research Letters.

Out to Sea

Warming air and sea temperatures are melting the ice in the region's permafrost, or perpetually frozen earth. The meltwater then streams over the land and melts more permafrost, carrying sediment into the sea as it goes.

From 2002 to 2007, the melting ice caused the coast to disappear at a rate of about 45 feet (14 meters) a year. That's up from an annual average of 30 feet (9 meters) between 1979 and 2002 and 20 feet (6 meters) between 1955 and 1979.

Remains of the ghost town of Esook, a hundred-year-old trading post, have been buried underwater as a result of the erosion, Jones said.

And near the town of Lonely, Jones took a picture of a whaling boat that a few months later was swallowed by the sea after nearly a century on shore.

The erosion also threatens oil wells. At least one has already been lost since 2002, and another will soon be gone, if the melting continues at these rates.

Especially Vulnerable

Larry Hinzman, director of the International Arctic Research Center in Fairbanks, Alaska, said the permafrost in this region has a considerable amount of ice, which is one reason it is melting so fast.

"If it were a different soil type, it would have less ice and would not erode so quickly," said Hinzman, who was not involved with the research.

Hinzman said the findings "would not be representative of the whole Arctic, but there are many places in the Arctic where the permafrost does contain similarly massive amounts of ice.

"This is not an unusual landscape feature in Alaska, Canada, or Siberia, but it would be unusual in Greenland, Iceland, and [the Swedish archipelago] Svalbard," he said.

The researchers call for more study of the erosion patterns so that preservation plans can be devised and new development can avoid early demise.

"Erosion is a natural process, and it is likely that this coastline has experienced erosion for quite some time," Jones said. It's the speed at which it is now occurring that worries researchers.

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