Graduate Student Opportunities, Department of Civil Engineering, University of Manitoba

How will climate change impact British Columbia’s far north? In the area of interest (South Yukon, Stikine Watershed, Mount Edziza), as well of most of British Columbia is listed as “sensitive” to future climate changes. Note that Climate impacts and adaptation research is only just commencing in British Columbia (Canada 2002). A key to developing mitigation (or more likely adaptation) strategies is to understand how the temperatures varied in the past, and how
ecosystems evolved to adapt to those stresses.

Since Lachenbruch and Marshall’s classic study of subsurface temperatures in Alaska, there has been a great deal of
interest in studying climate change through reconstructing ground surface temperatures (GST) from borehole measurements (BHT). Note that the magnitude of temperature increases reconstructed from BHT records seems to contrast however, with some proxy based reconstructions of surface air temperature (SAT) that indicate lower amounts of warming over the same period. We present data suggesting that seasonal snowcover may bias climate reconstructions based on BHT in portions of the Canadian northwest. Eight sites west of the Canadian cordillera, were examined for long-term SAT and GST changes. At seven of these sites precise borehole temperature profiles are used for the first time since the 1960s, thereby exploring the linkage between GST and SAT. New readings were made at
four of these locations. All sites showed significant increasing SAT trends, in terms of annual mean minimum and maximum temperatures. Over a 54 year period, the minimum temperatures increased between 1.1C and 1.5 while the maximum increased between 0.8 C and 1.5 C, among those eight stations. Observations of GST at those sites, however, showed no obvious climate induced perturbations. We believe this disconnect between SAT and GST is attributable to an increase in snow cover in early winter, followed by an increasing trend toward earlier snow melt in the
region. Such seasonal bias has important implications for GST reconstructions based on borehole temperatures. These results support Mann and Schmidt’s conjecture about a seasonal bias in the GST reconstructions fromborehole surveys and counter assertions of lower historic earth temperatures.

The Stikine River and the Spatsizi plateau near Dease Lake, B.C. has been selected for this study because of its importance in mining, recreation, culture, fisheries, and its unsurpassed beauty. Along with other conservation-minded groups and individuals, ”Friends of the Stikine” Society has been advocating recognition and protection of the Stikine River main stem as part of a “management” strategy to preserve the integrity and natural balance of the watershed. Although Mt. Edziza and Spatsizi Provincial Parks contain large areas of the watershed at higher elevations, the Stikine River and all of its tributary valley bottoms remain vulnerable to these aforementioned changes. The area
has been classified as ”sporadic, discontinuous” permafrost (NRCAN).