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Proactive disclosure Print version   | |  Sand Dune & Climate Change Studies in the Prairie Provinces Drought Impacts
Drought has historically been the main climatic concern on the prairies. In order to assess the impacts of climate change on the prairies, the potential impacts of future droughts need to be addressed. Studies of the impacts of drought need to include, the changes in the distribution of arid conditions during drought, the potential impacts of drought on the prairie landscape, and climate change projections indicated by various computer simulations, known as General Circulation Models. The 1987-88 Drought Contrary to the common belief that the southern prairies are semi-arid, the "average" climate of the region is, in fact, humid to sub-humid. The sub-humid zone is almost entirely contained within the Palliser Triangle, delineated by Captain John Palliser in the 1850s as the driest region of the prairies. The Brown Chernozemic soils that characterize much of the southern prairies are also found almost entirely within this sub-humid zone (figure to right). During periods of drought, such as those observed in 1987 and 1988, much of the southern prairies are dominated by semi-arid conditions. These conditions are related to warmer temperatures and reduced precipitation, causing reduced moisture availability. Therefore, although the average climate of the southern prairies is sub-humid, droughts create extreme conditions that are distinctly semi-arid. These recurrent extremes necessitate that the flora, fauna, and people of the region be well-adapted to semi-arid conditions.
Source: The Effect of Drought on Sand Dunes Increased aridity caused by prolonged drought or climate warming could result in greater sand dune activity in the southern prairies. In areas where semi-arid conditions could prevail, this would likely result in an increase in blowout activity, re-activation of stabilized dunes and the merging of presently active sand dunes to form nearly continuous bare sand in some areas. Stabilized dunes would also be more sensitive to disturbance. Diligent management practices including alteration of grazing intensities, and land-use activities would likely be required to reduce further erosion of these sensitive sandy areas. Although the 1987-88 drought was severe, it was insufficient to cause widespread re-activation of sand dune areas. It is presently believed that a period of drought on the order of a decade or more would be required to cause widespread dune activity on the southern prairies. The actual impact of drought also greatly depends upon the climatic conditions occurring before the drought. If a drought occurs during an otherwise moist period, the impact will be less than if it occurs during a time that has been generally dry. The 1990s have generally been moist, so that the impact of drought has not been as significant as in previous decades. However, the possibility of a warmer and potentially drier climate raises the concern that droughts could have a greater impact on the prairies in the future.
Source: Climate Change Scenarios With the exception of the arctic, the prairie provinces are projected to experience the greatest temperature increase under doubled-CO2 conditions. Using computer-based General Circulation Models, climate change scenarios for the southern prairies project higher temperatures in every season (figure to right). These models also project increased winter and spring precipitation, but generally decreased precipitation in summer and fall. This could possibly cause increased evaporation rates and lower soil moisture levels. Analysis of drought risks also indicates that the frequency of droughts could increase dramatically. However, there may also be wetter periods when temperatures are cooler. Such changes could have significant impacts in dune soil areas including reduced vegetation cover and increased wind erosion during drought, greater variability in shallow groundwater levels, and increased water erosion during wet periods. Climate models provide only projections of possible future climate scenarios. Therefore, it is also important to use observed climate records and to determine actual impacts associated with changes in climate in the past or in other areas. This can include historical impacts such as the 1930s drought and impacts occurring prior to European settlement. In this way, it is possible to establish benchmarks or "thresholds" to help determine the significance of potential impacts associated with future climate change.
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