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USGS confirms high Arctic coast erosion On average Beaufort, Chukchi coastlines receding, with the highest rates of change on the shores of the Beaufort Sea ALAN BAILEY Petroleum News
Arctic Alaska is shrinking, according to a new report published by the U.S. Geological Survey. The report documents coastal erosion along much of the coastlines of the Alaska Beaufort and Chukchi seas, with erosion rates as high as 18.6 meters per year in some small sections of the Beaufort Sea coast.
The report comes as part of a national survey of shoreline change that USGS is conducting around the open-ocean shores of the Lower 48 and parts of the coastlines of Hawaii, Alaska and the Great Lakes.
The USGS researchers measured Arctic Alaska coastline changes by comparing topographic surveys conducted in the 1940s with information collected between 1997 and 2012 from aerial photographs, satellite images and laser-derived elevation models. Comparison data came from 25,567 transects around the coast, with 84 percent of these transects showing the coastline receding. The researchers did not make any distinction between different possible reasons for the retreat of the coast - potential reasons include erosion by the sea, the breaching of coast lakes, sea-level rise or land subsidence.
Much variation The researchers found that the rates of shoreline change have varied considerably around the Alaska Arctic region, ranging from a growth rate of 10.9 meters per year to that maximum recession rate of more than 18 meters per year, a rate of erosion among the highest in the world. On average, the shoreline has retreated at a rate of 1.4 meters per year. The Beaufort Sea coast is receding at an average rate of 1.7 meters per year, while the Chukchi Sea coast is on average receding more slowly, at an average rate of 0.3 meters per year. The highest rate of erosion took place on the Beaufort Sea coast between Cape Halkett and Pogik Bay, to the west of Harrison Bay, while the western side of Pogik Bay saw the highest rate of accretion.
The report says that the barrier islands around the coast have migrated significantly over the years, with an overall gain in surface area of the islands, as a result of a combination of land erosion and accretion. The report also comments that, unlike elsewhere around the United States, the northern coast of Alaska is protected by landfast sea ice for all but three months of the year. Projected and observed increases in the lengths of ice-free periods, particularly in the autumn when large storms are common in the Arctic, may cause accelerated shoreline erosion in the future, the report says.
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