 |
| Titel |
Observing Muostakh disappear: permafrost thaw subsidence and erosion of a ground-ice-rich island in response to arctic summer warming and sea ice reduction |
| VerfasserIn |
F. Günther, P. P. Overduin, I. A. Yakshina, T. Opel, A. V. Baranskaya, M. N. Grigoriev |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1994-0416
|
| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 9, no. 1 ; Nr. 9, no. 1 (2015-01-28), S.151-178 |
| Datensatznummer |
250116743
|
| Publikation (Nr.) |
 copernicus.org/tc-9-151-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Observations of coastline retreat using contemporary very high resolution
satellite and historical aerial imagery were compared to measurements of open
water fraction, summer air temperature, and wind. We analysed seasonal and
interannual variations of thawing-induced cliff top retreat
(thermo-denudation) and marine abrasion (thermo-abrasion) on Muostakh Island
in the southern central Laptev Sea. Geomorphometric analysis revealed that
total ground ice content on Muostakh is made up of equal amounts of
intrasedimentary and macro ground ice and sums up to 87%, rendering the
island particularly susceptible to erosion along the coast, resulting in land
loss. Based on topographic reference measurements during field campaigns, we
generated digital elevation models using stereophotogrammetry, in order to
block-adjust and orthorectify aerial photographs from 1951 and GeoEye,
QuickBird, WorldView-1, and WorldView-2 imagery from 2010 to 2013 for change
detection. Using sea ice concentration data from the Special Sensor Microwave
Imager (SSM/I) and air temperature time series from nearby Tiksi, we
calculated the seasonal duration available for thermo-abrasion, expressed as
open water days, and for thermo-denudation, based on the number of days with
positive mean daily temperatures. Seasonal dynamics of cliff top retreat
revealed rapid thermo-denudation rates of −10.2 ± 4.5 m a−1
in mid-summer and thermo-abrasion rates along the coastline of
−3.4 ± 2.7 m a−1 on average during the 2010–2013
observation period, currently almost twice as rapid as the mean rate of
−1.8 ± 1.3 m a−1 since 1951. Our results showed a close
relationship between mean summer air temperature and coastal thermo-erosion
rates, in agreement with observations made for various permafrost coastlines
different to the East Siberian Ice Complex coasts elsewhere in the Arctic.
Seasonality of coastline retreat and interannual variations of environmental
factors suggest that an increasing length of thermo-denudation and
thermo-abrasion process simultaneity favours greater coastal erosion. Coastal
thermo-erosion has reduced the island's area by 0.9 km2 (24%)
over the past 62 years but shrank its volume by 28 x 106 m3
(40%), not least because of permafrost thaw subsidence, with the most pronounced
with rates of ≥− 11 cm a−1 on yedoma uplands near the
island's rapidly eroding northern cape. Recent acceleration in both will
halve Muostakh Island's lifetime to less than a century. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|