Erosion accelerates along Alaskan coast

Rates of erosion along Alaska’s northern coast have more than doubled in recent decades, overhead views suggest.

ALL FALL DOWN. Erosion of the permafrost cliffs along Alaska’s Arctic coast (note slumping blocks at center) has more than doubled. G. Clow/U.S. Geological Survey

Mud-rich permafrost cliffs standing 3 to 4 meters tall constitute much of the shore that runs from Barrow, Alaska, to the Canadian border. In some spots, the coast has moved inland more than 900 m during the past 50 years, says John C. Mars, a geologist with the U.S. Geological Survey in Reston, Va. He and USGS colleague David W. Houseknecht compared an aerial survey conducted in 1955 with more-recent satellite images to gauge erosion along the Arctic Ocean coastline.

Between 1955 and 1985, about half a square kilometer of land fell into the sea each year along a 130-km-long subsection of the coast, says Mars. Between 1985 and 2005, however, the average annual rate of erosion there more than doubled to 1.08 km2.

Causes of the recent boost in erosion aren’t clear from this study, the researchers note in the July Geology. A warming climate in the past few decades could have rendered the permafrost cliffs more susceptible to erosion, and a decrease in the Arctic Ocean’s summer-ice coverage may have increased wave action along the shore.

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