92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Tuesday, 24 January 2012
An Assessment of Canadian Prairie Drought: Past, Present, and Future
Hall E (New Orleans Convention Center )
Barrie R. Bonsal, EC, Saskatoon, SK, Canada; and P. Gachon, R. Aider, and S. Lapp

Droughts are one of the most dramatic manifestations of extremes in the water cycle. Prolonged, large-area droughts are among the world's costliest natural disasters having major impacts on agriculture, forestry, industry, municipalities, recreation, human health and society, and aquatic ecosystems. Within Canada, the Canadian Prairies are particularly drought-prone mainly due to their location in the lee of the western cordillera. Although previous studies examined the occurrence of Canadian Prairie droughts during instrumental, pre-instrumental and to a lesser extent, future periods, none have specifically focused on their trends and variability over all three scales. Using the Palmer Drought Severity Index (PDSI) and Standardized Precipitation Index (SPI) as drought indicators, this investigation assesses the variability of summer drought occurrence over a core region of the Canadian Prairies during a) the pre-instrumental record extending back several centuries (as inferred from tree rings), b) the instrumental record (1901-2005), and c) the 21st century as projected by several Global Climate Models with multiple emission scenarios. Results show that pre-instrumental droughts were generally more prolonged and severe than those during the 20th century. Projected changes to future droughts differ between the two drought indicators. The PDSI suggests increases in drought frequency and in some cases, severity particularly, after 2050. Conversely, SPI generally shows no significant changes to future drought frequency over the region. All future scenarios for PDSI and SPI do, however, suggest increased variability in drought-related extremes. This study can be considered an initial step toward quantifying and understanding Canadian Prairie drought occurrence over several centuries as determined from paleo, instrumental, and climate model data sources.

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