Permafrost exists wherever ground temperatures remain below 0°C throughout the year. At present, approximately 50% of the Canadian land surface is underlain by permafrost, and a significant portion of this has an average temperature that is warmer than -2°C. With climate warming, this warmer permafrost may ultimately disappear. Thawing of ice-rich permafrost may present hazards to infrastructure, and may also increase landslide activity.

Map 2 larger image [GIF, 78.9 kb, 718 X 533, notice]

The impacts of permafrost thaw will be highest in regions of ice-rich permafrost, which include areas underlain by organic and fine-grained soils. As shown in Map 2, the impact of permafrost thaw may be moderate to high over a large portion of the region containing warmer permafrost (area south of the -2°C isotherm). Increased thaw settlement may occur beneath buildings, utility systems, roads, railways, pipelines, containment dams and dykes. Remedial action may be required. Future development in these areas must consider the increased permafrost thaw and ground instability that may accompany climate warming.

Contact: Sharon Smith

Contact: Margo Burgess