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Thematic Guide to Integrated Assessment Modeling
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The McKenzie Basin Impacts Study
This study in "integrated regional assessment" focuses on a major watershed, the McKenzie Basin of northern Canada. The McKenzie is the 10th largest river basin in the world, with an area of about 1.8 million square kilometers, but is sparsely settled and developed with a population of only about 150,000. The region is resource-rich, presently has a harsh climate, and is projected to experience a considerably changed climate. Consequently, climate change may substantially affect the region's development. Environment Canada began the six-year impact study in 1990 (Cohen 1993; Cohen 1994).The study uses scenarios for both climate change and socioeconomic trends over a 50-year time horizon. Four climate scenarios of disparate kinds are used: two doubled-CO2 equilibrium runs of Global Circulation Models (GCM)--one from the Canadian Climate Centre (CCC) and one from the Geophysical Fluid Dynamics Laboratory at Princeton (GFDL-R30); one transient GCM run from the Goddard Institute of Space Studies (GISS) (Hansen et al. 1988); and one "composite" scenario, developed by judgmental combination of grid-point data from the Canadian GCM, climates of past warm years, paleoclimatic data, and "positional analogs" that impose the climate of one place on another.
Four scenarios of population growth and socioeconomic development are also employed, which attempt to represent the high variance of plausible development paths for the region, from high growth through substantial decline.
The study is loosely coordinated. The project provides modest funding for about 40 research initiatives based in universities and federal and provincial agencies, which are conducting analyses at different time and space scales, using a wide variety of disciplinary methods. To accommodate the diversity of participating studies, project organizers have used geographical information systems (GIS) and interpolation techniques to move from the rather sparse weather observation data available in the region to a specification of both baseline climate and future climate scenarios at extremely fine resolution, with monthly temperature and precipitation defined at 3,800 grid points in the study region. Though organizers acknowledge that the interpolation is crude, they took this measure to insure that all participating studies, even those working on very small scale, will work with climatic data derived consistently from common baseline observations.
Ideally, each participating study would examine its mandate (impact sector and location) 17 times, under baseline conditions and under each combination of the four future climate and four future socioeconomic scenarios. Organizers acknowledge, though, that this may not be possible, because some studies may lack the methodological tools or the resources to do so.
The study plans explicitly to integrate across sectors, considering impacts on each sector with accompanying changes in other sectors. One form of integration will use a reduced form of a Canadian regional input-output model, modified to treat the McKenzie Basin as one region and to reduce the number of industries. In addition, two independent subprojects are developing more ambitious integration schemes, using natural-resource accounting techniques, GIS, and land- resource assessment, to develop multi-attribute integrating schemes. Finally, the project expresses a still more ambitious goal of integrating information from physical, biological, and social sciences with traditional native knowledge of regional resources, their use, and their climate dependence.
This study has paid careful attention to including members of its potential audience and affected interests in the formulation of assessment questions and selection of component studies. The four large policy-relevant questions that are driving the study were developed early by a consultative group including federal, provincial, and territorial officials, scientists, and representatives of private industry and native groups. The questions are as follows:
- What are the implications of climate change for regional development objectives, and is there a need to alter resource planning?
- Does climate change pose the risk of an increase in resource conflicts?
- What are the major tradeoffs in management response, e.g., requirements for changed management strategy in national parks?
- What are the implications of climate change for community management of resources under native land-claim agreements?
Of the assessments reviewed here, this study goes the furthest in defining policy-relevant questions at the outset and involving its audience in study design. Several factors appear to pose challenges for the study's goal of effective, consistent integration, though: the diversity of component studies and relatively light control exercised over them; the delegation of the development of fundamental integrating frameworks to component studies that are being conducted in parallel with sectoral studies; and the constraints of resources and time.
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