Focal point: Jerry Brown

Permafrost temperature reflects integrated changes in ground surface energy balance, in turn reflecting possible climate change.

Permafrost refers to earth materials that remain at or below 0°C for at least two consecutive years. In the Northern Hemisphere, permafrost regions occupy approximately 23 million km2, with permafrost underlying between 12 and 17 million km2. These areas include large regions of Canada, China, Mongolia, Russia and Alaska, and with smaller permafrost areas at higher elevations in mountain chains of many other countries in both the Northern and Southern Hemispheres. The thickness of permafrost can exceed 600 m in the high latitudes. Southward, permafrost thins and becomes discontinuous. Unlike snow and ice covers, permafrost is not easily observed remotely, and requires in situ observations to define its extent and properties.

 

Monitoring of permafrost and active layer

Permafrost monitoring is conducted mainly through ground-based, point measurements. Permafrost thermal state (i.e. ground temperature) and active layer thickness are the key permafrost variables identified for monitoring under the GCOS/GTOS programmes. The Global Terrestrial Network for Permafrost (GTN-P), approved in 1999 and coordinated by the International Permafrost Association (IPA), comprises two international monitoring networks: Thermal State of Permafrost (TSP) and Circumpolar Active Layer Monitoring (CALM). More than 15 countries participate in these networks.

Permafrost temperature data are essential for detecting the terrestrial climate signal in permafrost terrain. The temperature signal in permafrost provides an indication of integrated changes in the ground surface energy balance, that in turn may reflect changes in climate. Many permafrost temperature records are of short duration and discontinuous, but some sites have continuous time series 20 to 30 years long.

Network extent and plans

The majority of the monitoring sites are located in the high latitude and high altitude regions of the Northern Hemisphere. Existing and new sites in Antarctica and the subantarctic are being added. The GTN-P is largely composed of regional networks, including the Mackenzie region in Canada; an Alaskan transect and deep boreholes in northern Alaska; the Permafrost and Climate in Europe (PACE) programme of boreholes, largely in alpine permafrost; and regional networks in China, Russia and Mongolia.

Currently, 125 sites, in both hemispheres contribute to CALM, which has operated for the last decade. The more recently established TSP has identified over 550 boreholes that can potentially contribute to GTN-P. Metadata and site information are available for many of these candidate boreholes (see GTN-P Web site). Both TSP and CALM are included in the International Polar Year (IPY) programme Permafrost Observatory Project (#50). Permafrost temperature measurements at many sites are planned for 2007–2008 to obtain a “snapshot” as a contribution to the IPY.

A long-term commitment, however, is required to establish a permanent network of permafrost observatories as part of GTN-P.

Data products and coordination

No international funding is available explicitly for data management, and so this has been done largely on a voluntary basis. Management and dissemination of active layer data for CALM is currently supported through a grant from the U.S. National Science Foundation. Data management for TSP is partially supported by the Geological Survey of Canada through its research programmes. Both CALM and TSP contribute soil temperature and moisture data to the Terrestrial Ecosystem Monitoring Sites (TEMS) database. Several IPY proposals are pending, and, if funded, will provide additional resources for producing a comprehensive retrospective and contemporary database on the state of permafrost. IPA coordinates GTN-P activities with other international programmes, including the World Climate Research Programme - (WCRP-CliC) and the Integrated Global Observing Straregy – Cryosphere (IGOS - Cryo).

GTN-P Site selection criteria
Boreholes selected meet the GCOS/GTOS hierarchical system for surface observations, of the Global Hierarchical Observing Strategy (GHOST) as well as meeting the following criteria:
1. Site data well documented and freely available.
2. Well-documented methodologies employed.
3. Reasonable assurance for long-term measurements.
4. Sites in under-represented areas have priority.
5. Readily accessible sites with long-established research and funding commitments preferred.

Benefits
Participation in the GCOS/GTOS networks will facilitate use of the data by international organizations such as the Intergovernmental Panel on Climate Change (IPCC) and the Arctic Climate Impact Assessment (ACIA), and improve justification for national and multi-national funding. The initial role of the IPA permafrost network is to organize the systematic collection and distribution of standardized data. The Geological Survey of Canada is providing the international data management for the GTN-P borehole temperature monitoring programme and maintains the GTN-P web site on its Permafrost internet site. Metadata for network sites will be accessible as well as regularly submitted summary data. GTN-P data would be subsequently archived through the National Snow and Ice Data Centre, Boulder, Colorado, as part of the IPA's Global Geocryological Database. Summaries and interpretations of data will be prepared every five years.

Additional information

For more information please refer to:

GTN-P
CALM
IPA
FGDC