CU-Boulder Study - Portions Of N. Alaskan Coast Now Disintegrating/Receding At 30 Meters/Yr

[hatrack]

The northern coastline of Alaska midway between Point Barrow and Prudhoe Bay is eroding by up to one-third the length of a football field annually because of a "triple whammy" of declining sea ice, warming seawater and increased wave activity, according to new study led by the University of Colorado at Boulder.

The conditions have led to the steady retreat of 30 to 45 feet a year of the 12-foot-high bluffs -- frozen blocks of silt and peat containing 50 to 80 percent ice -- which are toppled into the Beaufort Sea during the summer months by a combination of large waves pounding the shoreline and warm seawater melting the base of the bluffs, said CU-Boulder Associate Professor Robert Anderson, a co-author on the study. Once the blocks have fallen, the coastal seawater melts them in a matter of days, sweeping the silty material out to sea.

Anderson, along with collaborators Cameron Wobus of Stratus Consulting and Irina Overeem of CU's Institute of Arctic and Alpine Research, or INSTAAR, each presented results from components of their study at the annual meeting of the American Geophysical Union in San Francisco held Dec. 14-18.

The problem is caused by several factors, including increased erosion along the Alaskan coastline due to longer ice-free summer conditions and warmer seawater bathing the coast, Anderson said. The third potential factor is that the longer the sea ice is detached from the coastline, the further out to sea the sea-ice edge will be. This open-ocean distance between the sea ice and the shore, known as the "fetch," increases both the energy of waves crashing into the coast and the height to which warm seawater can come into contact with the frozen bluffs, said Anderson. "What we are seeing now is a triple whammy effect," said Anderson. "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."

EDIT

http://www.eurekalert.org/pub_releases/2009-12/uoca-poa121409.php

[OKIsItJustMe]

1. See Also

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=222008&mesg_id=222008

[RaleighNCDUer]

2. "frozen blocks of silt and peat"

peat being, of course, little more than compressed trapped carbon - give it a couple million years and it would be oil. So, as the bluffs disintegrate they continually release trapped carbon and methane into the atmosphere, creating a feedback loop, further contributing to air temp rise.