ANNUAL AND SEASONAL CLIMATE AND CLIMATIC CHANGES IN THE CANADIAN PRAIRIES SIMULATED BY THE CCC-GCM

As part of a study on the effects of climatic variability and change on the sustainability of agriculture in Alberta, the modelling performance of the second-generation Canadian Climate Centre GCM (general circulation model) is examined. For the region in general, the simulation of 1 x CO2 mean temperature is generally better than that for mean precipitation, and summer is the season best modelled for each variable. At the scale of individual grid squares, DJF (December, January, February) (temperature) and JJA (June, July, August) (precipitation) are the seasons best modelled. The GCM-simulated increases in mean annual temperature resulting from a doubling of CO2 are of the order of 5 to 6 degrees C in the Prairie region, with much of this increase resulting from substantial warming in the winter and spring. Increases in mean annual precipitation are of the order of 50 to 150 mm (changes of +5 to +15%), with the greatest changes again occurring in winter and spring. As far as the limited GCM run durations allow, temperature and precipitation variance generally show no significant changes from a 1 x CO2 to a 2 X CO2 climate. Increased precipitation in winter and spring does not result in greater snow accumulations owing to the magnitude of warming; and significant decreases in soil moisture content occur in summer and fall. The resulting effects on the growing season and moisture regime have the potential to affect agricultural practices in the area.