||This dataset consists of the Home Page for the Circumpolar Active Layer Monitoring (CALM) program as well as multiple directories and files of jpg and gif images, docs, html files, powerpoint, xls and txt files. The data are from a CD and are contained in a single gzipped tar file. The CALM program is designed to monitor and model changes in the thickness of the active layer above permafrost. CALM consists of 81 research sites operated by researchers from Austria, Canada, China, Denmark/Greenland, Kazakstan, Poland/Svalbard, Russia, Sweden/Svalbard, Switzerland and the United States. Investigators at these sites measure the seasonal thaw depth across plots using a standard protocol. Soil and air temperature, and soil moisture content, are also measured at many sites using a standard format. The soil, landscape, and vegetation at each site is also described.