The GSC's most recent map of permafrost and ground ice conditions in Canada was published in the 1995 National Atlas (a modified version of this map is presented under the discussion of permafrost distribution). This map delineates the boundaries of the continuous, discontinuous, and sporadic permafrost zones, and further subdivides these according to ground ice contents associated with surficial materials. Boundaries in this compilation are based on field observations, thermal and climatic data and physiographic regions. In addition, large bodies of ground ice, such as pingos, ice wedges and massive icy beds are mapped. The GSC has also been a principal collaborator in an International Permafrost Association project which culminated in the 1998 release of a Circumpolar Permafrost Map.

Observations of permafrost temperatures and thickness from GSC and other sources have been gathered into national databases.

Since 1990, the GSC has established a set of instrumented sites, designed to monitor the active layer in the Mackenzie Valley and Delta to describe variability over time as well as space. The system crosses several permafrost boundaries and traverses a number of ecoclimate regions, with measurement locations in a variety of situations. Several of the sites have been designated as Circumpolar Active Layer Monitoring (CALM) stations and data resides in the Global Geocryological Database of the International Permafrost Association.

Thaw depth monitoring sites in the Mackenzie Valley area. Yellow dots correspond to active layer monitoring sites and the red dots are sites with air and ground temperature record. larger image [JPEG, 158.4 kb, 623 X 615, notice]

Thaw depth monitoring sites in the Mackenzie Delta area. Yellow dots correspond to active layer monitoring sites and the red dots are sites with air and ground temperature record. larger image [JPEG, 79.6 kb, 492 X 515, notice]

Over 60 sites have been established along a 1200 km transect to monitor processes linking climate, climate change, permafrost and the active layer. Annual maximum thaw penetration and surface movement are measured using water-filled tubes anchored in permafrost. Active layer thickness calculated from the maximum depth of thaw in the tubes and surface movement, varies more with local soil properties, vegetation and microclimate than with regional atmospheric climate. While thaw penetration has increased at most sites, this is not always reflected by an increase in active layer thickness because of thaw settlement. Air and shallow ground temperatures are measured by miniature data loggers at many sites.

The histogram above illustrates year-to-year variation of maximum thaw penetration at selected sites, measured from an arbitrary stable reference point independent of the surface.

In association with its research projects in the Mackenzie region and western NWT, the GSC has instrumented many shallow (<25 m) and a few intermediate (25-125 m) boreholes with multisensor temperature cables for studies of the thermal regime in permafrost. Ground temperature monitoring has continued over the years at many of these locations, such as at sites associated with the Norman Wells pipeline research program, where data have been collected since 1984-85, and sites associated with the active layer monitoring program. In a few instances, deeper holes have specifically been drilled for long-term climate change studies.

Temperature data is collected, either manually at frequencies ranging from seasonally to annually, or through multichannel data loggers recording several times daily. Several of the GSC borehole sites have recently been proposed as candidates for an international permafrost temperature monitoring network being established by the International Permafrost Association. Go to GTNP.

Ground temperature monitoring site 84-3A near Fort Norman (Tulita) showing temperature records from several depths. Data logger records every 6 hours from June 1995 to August 1997.

Ground temperatures up to depths of 60 m have been measured manually since 1978 on a regular basis at five borehole sites on northern Ellesmere Island at Canadian Forces Station Alert, Nunavut in a collaborative project between the Department of National Defence and the Geological Survey of Canada. These boreholes represent the most northerly permafrost monitoring site in the world and the 23 year data set is one of the longest records of permafrost temperatures in Canada. Funding received from the Federal Government's Climate Change Action Fund (CCAF) allowed the installation of dataloggers and air and ground surface temperature sensors in summer 2000. Further funding received from Action Plan 2000 facilitated the installation of snow monitoring stations in collaboration with Environment Canada at three of the boreholes in summer of 2002. View Poster on GSC Monitoring Activites in the Western High Arctic [ZIP, 3.5 Mb]

Location of High Arctic permafrost observatories. larger image [JPEG, 66.7 kb, 431 X 386, notice]

Observed and mean annual ground temperature (MAGT) at CFS Alert at a depth of 15 m from 1978 to 2001. Monthly mean temperatures determined from data logger records are shown after July 2000. Analysis of permafrost temperature data indicates that from the mid to late 1990s, mean annual permafrost temperature at a depth of 15 m has increased by about 0.15°C per year. larger image [JPEG, 59.8 kb, 514 X 223, notice]

In the early 1990s, ground temperature cables and data loggers were installed at 3 hydrocarbon exploration wells in the Arctic Islands to monitor permafrost temperatures between depths of 10 and 70 m in order to detect any subtle ongoing climate change that may be occurring. The program had been suspended in the mid-1990s and CCAF funding supported its re-establishment in 2000 at 2 wells, Pat Bay on Lougheed Island and Gemini on the Fosheim Peninsula. Instrumentation was upgraded with high precision ground temperature dataloggers and a preliminary scientific analysis was conducted.

This figure shows predicted permafrost occurrence in the Fort Simpson study area under a 1°C and 2°C increase in mean annual air temperature, and current climate conditions (mean annual air temperature of -4°C). Blue indicates rivers or lakes, green corresponds to unfrozen material, and white indicates permafrost thicknesses between 1 and 5 m, light grey between 5 and 10 m, and dark grey between 10 and 15 m. The Norman Wells pipeline is shown in yellow and Mackenzie Highway in red. larger image [GIF, 61.9 kb, 500 X 663, notice]

A permafrost prediction model has been developed which integrates key environmental factors controlling the occurrence of permafrost. The model provides predictions of permafrost occurrence, temperature and thickness under conditions of climatic equilibrium. Digitized environmental factors required by the model include surficial geology, topography (in the form of a digital elevation model), vegetation, organic cover, and climate data (freezing and thawing degree-days). Validation of the model has been undertaken through its application to 180 test sites along the Norman Wells pipeline right-of-way for which borehole observations of permafrost occurrence have been recorded. Overall, the model correctly predicted the presence or absence of permafrost at 87% of the borehole sites, and predictions of permafrost thickness agreed favourably with information derived from a subset of 26 boreholes instrumented with temperature cables. The model employs relatively simple numeric methods and has been implemented within a Geographic Information System (GIS). The modelling system has been applied to regional permafrost mapping projects at two locations in the discontinuous permafrost zone of the Mackenzie Valley, Fort Simpson and Norman Wells, under present climate conditions and for increases in mean annual air temperature of 1 and 2°C.