Assessment of climate change on the Canadian prairies from downscaled GCM data

Climate data were taken from the Canadian Centre for Climate Modelling and Analysis (CCCma) Second Generation Global Circulation Model (GCMII) and the more recently developed Canadian Coupled Global Circulation Model with aerosol (CGCM1-A). The GCM output difference for a current and doubling CO(2) concentration was used to modify a 30-year historic time series. Regional climate change data under a doubling of CO(2) were produced by downscaling to a grid of 50 by 50 km across Alberta, Saskatchewan and Manitoba. Two scenarios were produced containing GCM-generated temperatures and precipitation. Results show that, across all three provinces, maximum air temperature is predicted to have a mean increase of 4.0degrees to 5.7degreesC (GCMII) and 2.5degrees to 3.3degreesC (CGCM1-A) above climate normal values. Minimum air temperature is expected to have a mean increase of 5.0degrees to 5.6degreesC (GCMII) and 3.0degrees to 3.3degreesC (CGCM1-A). Precipitation is predicted to have a mean increase of 29 to 36% (GCMII) and 3 to 7% (CGCM1-A). Both the GCMII and CGCM1-A indicate that central Alberta will benefit the most during the summer and winter from increased precipitation, the eastern Prairies, however, will see little change (winter) in precipitation with smaller increases (30 mm under GCMII) or a decrease (30 mm under CGCM1-A). Overall, the CGCM1-A results are more consistent than GCMII with historic large-scale spatial patterns.