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TABLE OF CONTENTSGeoscience and Climate Change in the Palliser Triangle of the Southern Canadian Prairies Economists' Statement on Climate Change Designing Economic Instruments to Reduce Greenhouse Gas Emissions in North America International Global Change Programs - Structures for Understanding Paleoenvironmental Studies in Saanich Inlet, British Columbia Biodiversity Conservation in Quebec National Science Meeting of the Ecological Monitoring and Assessment Network (EMAN) CCP INFO
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Geoscience and Climate Change in the Palliser Triangle of the Southern Canadian PrairiesR.E. Vance and D.S. LemmenGeological Survey of Canada, Natural Resources Canada In 1860, after four years surveying what was to become the heartland of Canada's wheat production, Cpt. John Palliser wrote that the semi-arid grassland of the western Canadian interior would be "forever and comparatively useless" for agriculture. In spite of his assessment, this 200,000 km2 area of southern Alberta, Saskatchewan, and Manitoba has become one of the world's most productive agricultural regions, despite severe social and economic hardships suffered by its inhabitants during two decades that were punctuated by drought events (one in the 1930s and again in the 1980s). The effects of these lengthy, warm, dry episodes and predictions from general circulation models (GCMs) of increased aridity in the North American interior resulting from increased greenhouse gas concentrations have raised concerns about regional agricultural sustainability. In 1991, the Geological Survey of Canada (GSC) established the Palliser Triangle IRMA (Integrated Research Monitoring Area) to assess the potential consequences of climate change by producing a high-resolution paleoclimatic record for the region, documenting the nature of landscape and hydrologic responses to past climatic variability and change, and identifying areas most vulnerable to geomorphic impacts through spatial analysis of landscape sensitivity. The paleoclimatic record, based on multiple proxy-climate indicators and spanning several thousand years, contains several climate change events and provides an indication of the possible range of climate extremes. In addition, by documenting the impacts these past climate changes have had on land and water resources, the paleo-record provides analogues for impacts associated with GCM climate change predictions. The paleoclimatic component of the Palliser Triangle IRMA has been focused on multiple proxy-climate indicators in lengthy (ca. 4,000-10,000 yrs) sedimentary records recovered from nine lakes that span elevational and hydrologic gradients. These records identify past periods of significantly enhanced and reduced aridity, compared to the historic record, and the response of both biotic and abiotic landscape components. The interval between ca. 7.5 and 4.0 ka BP serves as a potential analogue for the impacts of climate change with doubling of atmospheric CO2, since mean annual temperature at that time was 1-2° C warmer and growing season precipitation was reduced by 15% compared to today. This prolonged period of warmer and drier than present conditions was associated with a lowering of the regional water table by more than 4 m below present levels, and an increase in the salinity of remaining surface and shallow subsurface waters. Hence, Palliser Triangle IRMA paleoclimatic studies underscore the point that freshwater resources may become the critical limiting factor to agricultural sustainability in the Palliser Triangle as atmospheric greenhouse gas concentrations continue to increase. Geomorphic systems in semiarid and subhumid environments are often delicately balanced and, as a result, are sensitive to even minor changes in climate. Since human-induced climate changes in the 21st century are expected to include more frequent droughts, the geomorphic component of the Palliser Triangle IRMA has focused on landscape components that may be impacted in ways that threaten agricultural sustainability with a warmer and drier climate than present. Eolian (sand dune) landscapes are widespread in the Palliser Triangle, and are particularly responsive to climate change. The most recent episode of wide-scale sand dune activity occurred within the last 200 years, in response to a drought decade more severe than any of this century but far less severe than occurred more than 4000 years ago. Monitoring recent sand dune activity and studies of past activity indicate that the entire Palliser Triangle region is on the threshold of extensive sand dune activity. This threshold will probably be crossed with increasing drought frequency. Although regional hydrologic changes associated with past climate changes have been identified, the geomorphic response of fluvial systems is far less predictable. The inherent complexities of these systems are exacerbated in the Palliser Triangle because surface flow is derived mainly from the Rocky Mountains to the west, but sediment loads are largely derived from local areas on the prairies. However, since most sediment within through-flowing streams is derived immediately adjacent to the river channels, geomorphic impacts related to climate change will be largely restricted to floodplain environments. Climate, by modifying the regional ground water table, also influences the frequency of mass wasting processes. A shift towards a warmer and drier climate should promote slope stability, unless such a shift is associated with an increased frequency of high magnitude storms and floods that could trigger landslides. Soil erosion is the most critical geomorphic process affecting agricultural sustainability. Both wind and water erosion of soil are closely related to extreme climatic events (for example, a period of drought is a necessary precursor to widespread wind erosion). Warmer and drier climatic conditions could reduce the amount of crop residue returned to the soil, and higher incidence of fallowing could have a severe, long-term impact on soil degradation. However, because climatic impacts are unlikely to be catastrophic unless accompanied by poor land management practices, human activities remain the most critical factor influencing erosion of agricultural soils. Identification of these possible responses to climate change sets the stage for proactive land management, facilitating rapid adaptation or implementation of mitigating procedures if reliable, long-term regional climatic predictions are available, or when trends can be clearly defined through monitoring. Although the majority of field and laboratory work in the Palliser Triangle IRMA is complete, the critical task of assembling the wealth of data into journal contributions, as well as producing GSC summary reports and maps of landscape sensitivity to climate change, remains to be done. In addition, the GSC is producing a multimedia CD on the Palliser Triangle project which should appeal to a spectrum of users from high school students to researchers. The CD will contain background information on many aspects of the region and the issues associated with climate change, in addition to complete reports and databases resulting from the research. For more information contact Dr. Robert Vance, Geological Survey of Canada, Natural Resources Canada, 601 Booth St., Ottawa, Ontario K1A 0E8; tel: +1-613-947-7939; fax: +1-613-992-0190; e-mail: rvance@gsc.nrcan.gc.ca |