Impact of climate change scenarios on the agroclimate of the Canadian prairies

Regional climate change scenarios for the Canadian prairies were generated using historic weather data and daily data from two Canadian Climate Centre general circulation models (GCM). Model CGCMI-A was a recent version release while its predecessor was model GCMII. The GCM data were combined with historic values to generate two additional scenarios. All scenarios were used to drive the modified Versatile Soil Moisture Budget model that assessed soil moisture, aridity and other agroclimatic indices. The modelled results for all scenarios were compared to those using the historic climate data. The model predicted earlier seeding dates for spring wheat between 18 and 26 d. Early seeding and harvest was shown to be an appropriate adaptive strategy that avoided more arid conditions in the late summer. The soil water deficit was lower under GCMH than historic values by 46 mm. For CGCMl-A, the soil water deficit was decreased by 8 mm across the Prairie Provinces compared to historic values. GCM scenarios predicted unchanged or increased soil water in the top 120 cm soil across the Canadian prairies compared to the historic scenario. There were some regions such as southeastern Saskatchewan and southern Manitoba where reductions in summer rainfall (for CGCMl-A) were large. These regions experienced the greatest benefit of earlier seeding dates.