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Modeling erosion of ice-rich permafrost bluffs along the Alaskan Beaufort Sea coast

Journal of Geophysical Research F: Earth Surface

By:
, , , , ,
DOI: 10.1002/2013JF002845

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Abstract

The Arctic climate is changing, inducing accelerating retreat of ice-rich permafrost coastal bluffs. Along Alaska’s Beaufort Sea coast, erosion rates have increased roughly threefold from 6.8 to 19 m yr−1 since 1955 while the sea ice-free season has increased roughly twofold from 45 to 100 days since 1979. We develop a numerical model of bluff retreat to assess the relative roles of the length of sea ice-free season, sea level, water temperature, nearshore wavefield, and permafrost temperature in controlling erosion rates in this setting. The model captures the processes of erosion observed in short-term monitoring experiments along the Beaufort Sea coast, including evolution of melt notches, topple of ice wedge-bounded blocks, and degradation of these blocks. Model results agree with time-lapse imagery of bluff evolution and time series of ocean-based instrumentation. Erosion is highly episodic with 40% of erosion is accomplished during less than 5% of the sea ice-free season. Among the formulations of the submarine erosion rate we assessed, we advocate those that employ both water temperature and nearshore wavefield. As high water levels are a prerequisite for erosion, any future changes that increase the frequency with which water levels exceed the base of the bluffs will increase rates of coastal erosion. The certain increases in sea level and potential changes in storminess will both contribute to this effect. As water temperature also influences erosion rates, any further expansion of the sea ice-free season into the midsummer period of greatest insolation is likely to result in an additional increase in coastal retreat rates.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Modeling erosion of ice-rich permafrost bluffs along the Alaskan Beaufort Sea coast
Series title:
Journal of Geophysical Research F: Earth Surface
DOI:
10.1002/2013JF002845
Volume
119
Issue:
5
Year Published:
2013
Language:
English
Publisher:
American Geophysical Union
Contributing office(s):
Geosciences and Environmental Change Science Center
Description:
25 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research F: Earth Surface
First page:
1155
Last page:
1179
Number of Pages:
25
Country:
United States
State:
Alaska
Other Geospatial:
Beaufort Sea Coast