The Circumpolar Active Layer Monitoring Network-CALM: Long-term Observations on the Climate-Active Layer-Permafrost System

Authors: Nikolay Shiklomanov*, Department of Geography, The George Washington University, Washington DC, Frederick E. Nelson, Department of Earth, Environmental, and Geographical Sciences, Northern Michigan University, Marquette, MI , Dmitry A Streletskiy, Department of Geography, The George Washington University, Washington DC, Anna E Klene, Department of Geography, University of Montana, Missoula MT
Topics: Polar Regions, Cryosphere, Physical Geography
Keywords: Permafrost, Active-layer, Climate Change, long-term monitoring
Session Type: Paper
Day: 4/4/2019
Start / End Time: 9:55 AM / 11:35 AM
Room: Stones Throw 1 - Granite, Marriott, Lobby Level
Presentation File: No File Uploaded


The permafrost (perennially frozen ground) regions occupy nearly a quarter of the Earth's terrestrial surface. Permafrost is experiencing large changes stemming from the unprecedented degree of environmental change being observed in the Arctic. Changes in the permafrost system have profound effects on the ecology, hydrology, geomorphology, and human occupation of cold environments. The main indicators of permafrost stability are permafrost temperature and thickness of the active-layer (layer of earth materials between the ground surface and the top of the permafrost that undergoes an annual cycle of freezing and thawing). These parameters are considered to be Essential Climatic Variables (ECVs) by the Global Climate Observing System (GCOS) and the Global Terrestrial Observing Network (GTOS). Since mid 1990s the Circumpolar Active Layer Monitoring (CALM) program represents the only coordinated program providing collection, standardization, open access, and dissemination of active-layer data world-wide. At present, standardized active layer observations in the Northern Hemisphere are available for more than 200 CALM sites in the Northern Hemisphere. In this presentation we provide an overview of CALM network and observational methodology and use data from approximately 23 years (1995-2017) of continuous observations to examine temporal trends in ALT for several representative Arctic regions.

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