Increases in water scarcity represent the most serious climate risk. The Prairies are Canada's major dryland. Recent trends and future projections include lower summer streamflows, falling lake levels, retreating glaciers, and increasing soil- and surface-water deficits. A trend of increased aridity will most likely be realized through a greater frequency of dry years. Water management and conservation will continue to enable adaptation to climate change and variability. This could include technologies for improved efficiency of water use, as well as water pricing regimes that would more accurately reflect the real costs of water treatment and supply, and help to ensure that an increasingly scarce resource is properly allocated. Higher forest, grassland and crop productivity from increased heat and atmospheric CO 2 could be limited by available soil moisture, and dry soil is more susceptible to degradation. Water scarcity is a constraint on all sectors and communities, and may constrain the rapid economic and population growth in Alberta.
Ecosystems will be impacted by shifts in bioclimate, changed disturbance regimes (e.g. insects and fire), stressed aquatic habitats and the introduction of non-native plants and animals. Impacts will be most visible in isolated island forests and forest fringe areas. There are implications for livelihoods (e.g. Aboriginal) and economies (e.g. agriculture, forestry) most dependent on ecological services. Adjustments to ecosystem management are required to enable change to occur in a sustainable manner.
The Prairies are losing some advantages of a cold winter. Cold winters help limit pests and diseases, facilitate winter operations in the forestry and energy sectors, and allow access to remote communities though the use of winter roads. As winter temperatures continue to increase, these advantages will be reduced or lost. For example, the mountain pine beetle may spread into the Prairies' jack pine forests, exploration and drilling sites may become less accessible, and reductions in the length of winter road seasons are likely.
Resources and communities are sensitive to climate variability. The Prairies have one of the world's most variable climates. This variability has been both costly (e.g. an approximate $3.6 billion drop in agricultural production during the drought of 2001 –2002) and the stimulus for most of the adaptive responses to climate variability. Projections of future climate conditions include more frequent drought, but also increased precipitation in the form of rain and higher probability of severe flooding. Extreme events, and an expanded range of year-to-year departures from climate norms, represent greater risks to the economy of the Prairies than a simple shift in mean conditions.
Adaptive capacity, though high, is unevenly distributed. As a result, levels of vulnerability are uneven geographically (e.g. rural communities generally have less resources and emergency response capacity) and among populations (e.g. elderly, Aboriginal and recent immigrant populations are the fastest growing and more vulnerable to health impacts). Climate change could encourage further migration from rural to urban communities and to regions with the most resources (e.g. Alberta cities). Adaptive capacity will be challenged by projected increases in climatic variability and frequency of extreme events.
Adaptation processes are not well understood. Although a high adaptive capacity could reduce the potential impacts of climate change, it is unclear how this capacity will be applied. Most existing research does not capture adaptation measures and processes. Capacity is only potential — institutions and civil society will play a key role in mobilizing adaptive capacity. Recent adaptations, such as minimum tillage practices and crop diversification in the agriculture sector, water policy in Alberta, re-engineering of the Red River floodway, municipal infrastructure and water conservation programs, have enhanced resilience and increased adaptive capacity.