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 o n the sustainability of agriculture in Alberta, the modelling performa nce of the second-generation Canadian Climate Centre GCM (general circ ulation model) is examined. For the region in general, the simulation of 1 x CO2 mean temperature is generally better than that for mean pre cipitation, and summer is the season best modelled for each variable. At the scale of individual grid squares, DJF (December, January, Febru ary) (temperature) and JJA (June, July, August) (precipitation) are th e seasons best modelled. The GCM-simulated increases in mean annual te mperature 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 a nnual 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 preci pitation variance generally show no significant changes from a 1 x CO2 to a 2 X CO2 climate. Increased precipitation in winter and spring do es not result in greater snow accumulations owing to the magnitude of warming; and significant decreases in soil moisture content occur in s ummer and fall. The resulting effects on the growing season and moistu re regime have the potential to affect agricultural practices in the a rea.