Welcome to the web site for the Circumpolar Active Layer Monitoring Network-CALM: Long-Term Observations of the Climate-Active Layer-Permafrost System.

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 200 sites in both hemispheres. CALM currently has participants from 15 countries. Majority of sites measure active-layer thickness on grids ranging from 1 ha to 1 km², and observe soil temperatures. Most sites in the CALM network are located in Arctic and Subarctic lowlands. Southern Hemisphere component (CALM-South) is being organized and currently includes sites in Antarctic and South America. 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 has been supported independently and continuously since 1998 through grants from the U.S. National Science Foundation*. CALM is funded by the NSF Project OPP-1836377.

This web site contains archived data sets, a table of summary statistics, a map of the sites, measurement protocols, CALM forms, equipment installation instructions, uploading and downloading instructions, and other pertinent information.

*Any opinions, findings, conclusions, or recommendations expressed in on this site or in CALM publications are those of the authors and do not necessarily reflect the views of the NSF. Mention of specific products or manufacturers does not constitute endorsement by NSF.