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- Title
Climate Change Drives Widespread and Rapid Thermokarst Development in Very Cold Permafrost in the Canadian High Arctic.
- Authors
Farquharson, Louise M.; Romanovsky, Vladimir E.; Nicolsky, Dmitry; Cable, William L.; Walker, Donald A.; Kokelj, Steven V.
- Abstract
Climate warming in regions of ice‐rich permafrost can result in widespread thermokarst development, which reconfigures the landscape and damages infrastructure. We present multisite time series observations which couple ground temperature measurements with thermokarst development in a region of very cold permafrost. In the Canadian High Arctic between 2003 and 2016, a series of anomalously warm summers caused mean thawing indices to be 150–240% above the 1979–2000 normal resulting in up to 90 cm of subsidence over the 12‐year observation period. Our data illustrate that despite low mean annual ground temperatures, very cold permafrost (<−10 °C) with massive ground ice close to the surface is highly vulnerable to rapid permafrost degradation and thermokarst development. We suggest that this is due to little thermal buffering from soil organic layers and near‐surface vegetation, and the presence of near‐surface ground ice. Observed maximum thaw depths at our sites are already exceeding those projected to occur by 2090 under representative concentration pathway version 4.5. Plain Language Summary: Permafrost is ground that remains at or below 0 °C for two years or longer and it underlies much of the Arctic. Permafrost in Arctic lowland regions is frequently characterized by large volumes of ground ice which, when it melts, causes the ground surface to collapse. As the Arctic warms, ice‐rich permafrost degradation is expected to be widespread. Our data illustrate that very cold permafrost, which has a mean annual ground temperature of −10 °C or lower, is experiencing a rapid increase in active layer thickness at annual time scales. At three permafrost monitoring sites in the Canadian Arctic we have observed that warmer than average summer air temperatures have caused the active layer to deepen, near‐surface ground ice to melt, and the overlying ground surface to subside, in some cases leading to the formation of small thaw ponds. Our results show that very cold permafrost terrain is responding rapidly to ongoing warming. Key Points: Observed thermokarst development in very cold permafrost at three monitoring sites along a 700‐km transect in the Canadian High ArcticRapid landscape response to above average summer warmth is due to limited thermal buffering from overlying ecosystem components and near‐surface ground iceChange was greatest at Mould Bay where thawing index values were 240% above historic normals causing ~90 cm of subsidence in 12 years
- Subjects
NORTHERN Canada; CLIMATE change; THERMOKARST; COLD (Temperature); PERMAFROST
- Publication
Geophysical Research Letters, 2019, Vol 46, Issue 12, p6681
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2019GL082187