Circumpolar Active Layer Monitoring Network (CALM)

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The primary goal of the Circumpolar Active Layer Monitoring (CALM) program is to observe the response of the active layer and near-surface permafrost to climate change over long (multi-decadal) time scales. The CALM observational network, established in the 1990s, observes the long-term response of the active layer and near-surface permafrost to changes and variations in climate at more than 125 sites in both hemispheres. CALM currently has participants from 15 countries. Approximately 60 sites measure active-layer thickness on grids ranging from 1 ha to 1 km², and 100 sites observe soil temperatures, including permafrost temperatures from boreholes. Most sites in the CALM network are located in Arctic and Subarctic lowlands, although 20 boreholes affiliated with CALM are in mountainous regions of the Northern Hemisphere above 1300 m elevation. A new Antarctic component is being organized and currently includes 13 sites. The broader impacts of this project are derived from the hypothesis that widespread, systematic changes in the thickness of the active layer could have profound effects on the flux of greenhouse gases, on the human infrastructure in cold regions, and on landscape processes. It is therefore critical that observational and analytical procedures continue over decadal periods to assess trends and detect cumulative, long-term changes.

The CALM program began in 1991. It was initially affiliated with the International Tundra Experiment and was later (1998-2002) supported by a grant from the U.S. National Science Foundation’s Arctic System Science program to the University of Cincinnati and directed by Professor K. M. Hinkel. During a bridging year (2003) field operations in Alaska, Russia, Mongolia, and Kazakhstan were supported by the University of Delaware’s Center for International Studies. The CALM program is currently supported by a grant from NSF’s Arctic Research Support and Logistics program (OPP-0352958).* A brief history of CALM is available in the paper by Brown et al. (2000).

The CALM activity is hosted on the CALM website:

Access CALM data for the northern and southern hemispheres