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Volume 10, issue 6
The Cryosphere, 10, 2673–2692, 2016
https://doi.org/10.5194/tc-10-2673-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
The Cryosphere, 10, 2673–2692, 2016
https://doi.org/10.5194/tc-10-2673-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 15 Nov 2016

Research article | 15 Nov 2016

Presence of rapidly degrading permafrost plateaus in south-central Alaska

Benjamin M. Jones1, Carson A. Baughman1, Vladimir E. Romanovsky2,3, Andrew D. Parsekian4, Esther L. Babcock1, Eva Stephani1, Miriam C. Jones5, Guido Grosse6, and Edward E. Berg7,* Benjamin M. Jones et al.
  • 1Alaska Science Center, US Geological Survey, Anchorage, AK 99508, USA
  • 2Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
  • 3Earth Cryosphere Institute, 86 Malygina Street, 625000 Tyumen, Russia
  • 4Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82070, USA
  • 5Eastern Geology and Paleoclimate Science Center, US Geological Survey, Reston, VA 20192, USA
  • 6Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany
  • 7Kenai National Wildlife Refuge, US Fish and Wildlife Service, Soldotna, AK 99669, USA
  • *retired

Abstract. Permafrost presence is determined by a complex interaction of climatic, topographic, and ecological conditions operating over long time scales. In particular, vegetation and organic layer characteristics may act to protect permafrost in regions with a mean annual air temperature (MAAT) above 0 °C. In this study, we document the presence of residual permafrost plateaus in the western Kenai Peninsula lowlands of south-central Alaska, a region with a MAAT of 1.5 ± 1 °C (1981–2010). Continuous ground temperature measurements between 16 September 2012 and 15 September 2015, using calibrated thermistor strings, documented the presence of warm permafrost (−0.04 to −0.08 °C). Field measurements (probing) on several plateau features during the fall of 2015 showed that the depth to the permafrost table averaged 1.48 m but at some locations was as shallow as 0.53 m. Late winter surveys (augering, coring, and GPR) in 2016 showed that the average seasonally frozen ground thickness was 0.45 m, overlying a talik above the permafrost table. Measured permafrost thickness ranged from 0.33 to  >  6.90 m. Manual interpretation of historic aerial photography acquired in 1950 indicates that residual permafrost plateaus covered 920 ha as mapped across portions of four wetland complexes encompassing 4810 ha. However, between 1950 and ca. 2010, permafrost plateau extent decreased by 60.0 %, with lateral feature degradation accounting for 85.0 % of the reduction in area. Permafrost loss on the Kenai Peninsula is likely associated with a warming climate, wildfires that remove the protective forest and organic layer cover, groundwater flow at depth, and lateral heat transfer from wetland surface waters in the summer. Better understanding the resilience and vulnerability of ecosystem-protected permafrost is critical for mapping and predicting future permafrost extent and degradation across all permafrost regions that are currently warming. Further work should focus on reconstructing permafrost history in south-central Alaska as well as additional contemporary observations of these ecosystem-protected permafrost sites south of the regions with relatively stable permafrost.

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We combined field data collection with remote sensing data to document the presence and rapid degradation of permafrost in south-central Alaska during 1950–present. Ground temperature measurements confirmed permafrost presence in the region, but remotely sensed images showed that permafrost plateau extent decreased by 60 % since 1950. Better understanding these vulnerable permafrost deposits is important for predicting future permafrost extent across all permafrost regions that are warming.
We combined field data collection with remote sensing data to document the presence and rapid...
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