Effects of climate change on killing frost in the Canadian prairies

Killing frost is a significant factor that governs agricultural production on the Canadian prairies across Alberta, Saskatchewan and Manitoba. The objective of this study was to assess the potential changes in the spatial distribution of killing frosts for spring wheat Triticum aestivum L. on the Canadian prairies under projected future climates. To accomplish this, (1) daily climate data (from 1961-1990) at 60 weather stations across the agricultural regions of the Canadian prairies were obtained; (2) 3 climate scenarios were developed for the period 2040-2069; (3) killing frost indices for spring wheat were calculated for both the baseline and the 3 climate change scenarios for all weather stations, and (4) geostatistical methods were used to interpolate the indices from the stations to fine grids covering the whole agricultural regions on the Canadian prairies. Results show that under baseline conditions-with the exception of some pockets in all 3 provinces-areas with the earliest mean dates of last spring killing frost (LSKF) (April 12 to April 14) are located in Alberta and west-central Saskatchewan; while the earliest mean first fall killing frost (FFKF) (September 16 to September 20) occurs mainly in southwest Saskatchewan. The 3 climate change scenarios projected an earlier LSKF (April 6 or earlier compared to April 14) and a later FFKF (October 3 or later compared to September 27). As a result, there was a longer killing frost free period (KFFP), which increased under all scenarios by >= 14 d compared to the baseline climate. Although the changes differed among the climate change scenarios, the major characteristics were fairly consistent. The results from this study will help formulate strategies to address climate change across the Canadian prairies, such as seeding earlier and choosing cultivars with later maturity dates and longer growing periods.