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A case study of the regional impacts of climate change scenarios has been completed in the Mackenzie basin, a watershed that extends from the mid-latitudes to the subarctic in northwest Canada. A lengthy description of this case study, known as the Mackenzie Basin Impact Study, is available in Cohen (1994, 1996, 1997a,b,c). A sketch of the MBIS integrating framework is shown in Figure 15-10. Within this process, several types of integration exercises were used, including models, stakeholder consultation, and thematic discussions.
As a high-latitude watershed, the Mackenzie basin has been regarded as an area that might benefit in certain ways from a warmer climate. Taken individually, economic impacts could be quantified, and these impacts might show substantial benefits for the region. Other factors must be considered, however, and some of these factors may constrain the potential benefits:
Potential negative impacts of climate warming also must be considered because they may offset possible benefits. An example is the implication of hydrological and landscape changes on water management agreements. Initial projections of runoff and lake levels are for declines below observed minima (Soulis et al., 1994; Kerr, 1997). Peace River ice cover will be affected by temperature changes and changes in outflow from the Bennett Dam in northeast British Columbia (Andres, 1994). There continue to be uncertainties in projections of hydrological impacts; the Global Energy and Water Cycle Experiment (GEWEX) is addressing these uncertainties (see Chapter 16). There has been a strong warming trend in the region during the past 40 years, and Great Slave Lake experienced new record minimum lake levels in 1995.
It would appear that the other main threats to the Mackenzie landscape are accelerated erosion and landslides caused by permafrost thaw and extreme events (fire, storm surges), especially in sloping terrain and the Beaufort Sea coastal zone (Aylsworth and Egginton, 1994; Solomon, 1994; Aylsworth and Duk-Rodkin, 1997; Dyke et al., 1997); increased fire hazard (Hartley and Marshall, 1997; Kadonaga, 1997); changes in climate conditions that influence the development of peatlands (Nicholson et al., 1996, 1997; Gignac et al., 1998); and invasion of new pests and diseases from warmer regions (Sieben et al., 1997).
Impacts on fisheries and wildlife are difficult to project, as a result of lack of long-term data, complexity of life cycles, and incomplete information on responses to previous environmental changes (Brotton and Wall, 1997; Gratto-Trevor, 1997; Latour and MacLean, 1997; Maarouf and Boyd, 1997; Melville, 1997). Outside of MBIS, there have been few impact studies on North American boreal and Arctic freshwater fisheries (Weatherhead and Morseth, 1998). Some information is available on terrestrial wildlife and Arctic marine fisheries (see Chapter 16). Others have outlined the potential for freshwater ecosystem impacts, including loss or reduction of deltaic lakes, increased pondwater temperatures, side effects of permafrost thaw (including sedimentation of rivers), and changes in primary productivity depending on nutrient levels (Rouse et al., 1997; Schindler et al., 1997; Meyer et al., 1999).
First-order and second-order impacts eventually lead to others that are considerably more difficult to address. Will land claims or water resources agreements be affected? Would it be appropriate to artificially maintain historic water levels in the Peace-Athabasca delta within this scenario of climate change (see Chapter 16)? Could there be new conflicts over land use, especially if agriculture expands northward to take advantage of improved soil capability to support crop production (Brklacich et al., 1996, 1997b)? What might be the effects on parks and other protected areas (Pollard and Benton, 1994) and tourism (Staple and Wall, 1996; Brotton and Wall, 1997; Brotton et al., 1997; Wall, 1998a,b)? Could climate change affect the economics of commercial forestry (Rothman and Herbert, 1997) or oil and gas production in the Beaufort Sea (Anderson and DiFrancesco, 1997)?
Two exercises dealt with individual perceptions of aboriginal responses to future scenarios. The first asked for a listing of physical and biological impacts, as well as how aboriginal people would be affected if they continued to pursue a traditional aboriginal lifestyle or if they became more active in the formal wage economy (similar to the dual-economy situation described by Shukla, 1997). Results showed that perceptions of impact and vulnerability were influenced by visions of future lifestyles (Aharonian, 1994). The second exercise used input-output modeling and a community survey to look at responses to a potential benefit of warming—an opportunity for expanded activity in the formal wage economy (because of the longer summer) that would force people to relocate from their traditional community if they wanted the employment. Results showed a willingness to accept the opportunity, but there were concerns about social impacts on the community of relocation or creation of commuter workers who would be absent for extended periods (Lonergan and Kavanagh, 1997).
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