Permafrost weakening as a potential impact of climatic warming

The warming weakening of permafrost strength as a result of different scenarios of climatic warming ranging from 0 to 5[degrees]C over the next century has been predicted using a one-dimensional geothermal model. These predictions are based on the results of an intensive geotechnical program carried out in a warm ice-rich silty permafrost in Northern Quebec. The dependency of permafrost strength on temperature was assessed from cone penetration tests performed at regular intervals over a 2-month period during the seasonal warming of the upper permafrost layer in spring 2000. A thermomechanical subroutine taking into account this dependency has been then added to the one-dimensional geothermal model for the simulation of the weakening of permafrost strength as it warms. A warming rate of 0.02[degrees]C/year over the next century leads on a slow decrease in permafrost strength corresponding to a relative loss of strength of about 50%. For a warming rate of 0.05[degrees]C/year, the strength weakening is much more pronounced and almost reaches the unfrozen state at the end of the warming period corresponding to a relative loss of 98%. DOI: 10.1061/(ASCE)0887-381X(2010)24:1(1) CE Database subject headings: Freezing; Freeze and thaw: Thermal factors; Global warming; Climate changes; Canada. Author keywords: Freezing index; Thawing index; Surface n-factor; Surface temperature; Ground temperature; Thermal properties.