Scale in Integrated Assessments: Global Change and Local Places

Thomas J. Wilbanks

Oak Ridge National Laboratory

Oak Ridge, Tennessee

Scale is a growing issue in integrated assessments of global change. Global changes converge in localities, and changes at a local scale also contribute to global changes. Most integrated assessment to date has been top-down, i. e., scaling down from the global to the local scale, rather than bottom up. But the importance of local stake holders in determining responses to concerns about global changes is beginning to direct more attention to local and regional information and assessment. Wilbanks discussed his work on a current NASA-funded research project, Global Change in Local Places (Wilbanks, 1997), which focuses on three U. S. localities (the Blue Ridge/Piedmont of western North Carolina, the High Plains/Ogallala Aquifer area of southwestern Kansas, and the Great Lakes/manufacturing belt of northwestern Ohio), considering their greenhouse gas (GHG) emissions, driving forces, and mitigation capabilities (see Figure 1.38) at a scale of about one degree longitude by one degree latitude.

Wilbanks' thesis is that relationships between the macro and micro scales, and the interactions between macro-structure and micro-agency, affect the way the world works and deserve more attention than they have received in the global change research enterprise to date. This is not just an issue in understanding global change. Improving the understanding of linkages between macroscale and microscale phenomena and processes is one of the great overarching intellectual challenges of our age in a wide range of sciences. Biologists struggle to understand linkages between molecules, cells, and organisms; ecologists between patches, ecosystems, and biomes; and economists between firms, industries, and economies.

How Scale Matters

In theory, scale matters in studying global change, local dynamics are worth worrying about, and localities can make a difference. For instance, it is clear that some of the driving forces for global change operate at a global scale, such as the greenhouse gas composition of the atmosphere and the reach of global financial systems. But it seems just as clear that many of the individual phenomena that underlie microenvironmental processes, economic activities, resource use, and population dynamics arise at a local scale. In this paradox lies a dialectic that suggests the fundamental importance of scale. Wilbanks reviewed six basic arguments of two kinds regarding how scale matters: three arguments about the nature of reality (how the world works) and three arguments about the practice of science (how we perceive and learn about our world).

Relationships between the macro and micro scales, and the interactions between macro-structure and micro-agency, affect the way the world works and deserve more attention.

The Reality Arguments

Domain

The forces that drive global change arise from different domains of nature and society . These can be broadly divided into the systemic ( e. g., the effects of greenhouse gas emissions on the global climate system) and the cumulative (when ubiquitous localized changes become global phenomenon, e. g. , local pollution or species extinction). A more detailed approach views climate, ecology, and society as the domains, each of which includes phenomena which vary in their spatial and temporal scales of operation.

Agency

Agency is intentional human action, and it takes place within a structure of institutions. The scale of sociopolitical participation is often intrinsically localized while the scale of institutional structure is almost always more encompassing. Local agency is complicated in global change issues because, e. g., the locale of emissions is not necessarily the same as the locale of control over emissions. Some local emissions can be traced to local driving forces and decisions, such as electric power generation within an area to meet its own needs, but some local driving decisions result in emissions in other areas, such as local consumption of electricity generated in other areas. And many local emissions are the result of decisions made in other areas, such as emissions from through traffic on interstate highways.

Interaction

When global structure and local agency interact across very different domains, the resulting driving forces, changes, and consequences are not readily predictable or understood. The interaction of processes moving at different time scales and areal extents underlies a great deal of the current interest in complexity, nonlinear dynamics, and the search for order amid seeming chaos. Especially in regions where human activity predominates, interactions are highly diverse and complex.

When global structure and local agency interact across very different domains, the resulting driving forces, changes, and consequences are not readily predictable or understood.

These three arguments suggest that scale is an important variable in understanding the reality of global change. But even if things do not in fact work differently at different scales, it can still be argued that global understanding depends in fundamental ways on observations at a local scale for reasons related to the practice of science.

The Practice of Science Arguments

Tractability

It is argued that the central relationships underlying global change are too intractable, too complex to trace at any scale beyond the local, too difficult to keep grounded in direct observations, too likely to become disembodied from actual experience. The argument is that the complex relations among environmental, economic, and social processes that drive change at the global scale can only be unraveled by careful locality-specific research. The central problem in such case-specific research is that, while it is much more tractable, it is much less generalizable. Yet there are many examples of successful comparative studies using case studies which are carefully chosen for comparability and where a common protocol is used. For example, a study of poverty and environment (Kates and Haarmann, 1992) used 30 case studies from Africa, Asia, and Latin America which were not specifically designed to document poverty-environment linkages, to document the widely-held view that poverty and environmental degradation are strongly linked. The available studies told common tales of poor people's displacement from their lands, the division of their resources, and the degradation of their environments culminating in three major spirals of household impoverishment and environmental degradation driven by combinations of development/commercialization, population growth, poverty, and natural hazards. In this way, by careful comparison generic principles can emerge even from diverse case studies.

Variance

It also seems self-evident that the variance one detects in a portfolio of observations of geographic areas is likely to be greater when the areas themselves are smaller, at least if the overall geographic expanse covered by the sample is the same. For instance, the variance in greenhouse gas emissions per capita from a random sample of fifty U. S. counties would be expected to be greater than from the fifty states. In principle, this greater variety in processes and relationships at a more local scale represents an opportunity for learning more about the complex causes and consequences of global change, including the identification of interesting alternatives for mitigation and urgent needs for action that might otherwise be missed. For example, the variance in smaller-scale climates can serve as surrogates for more widespread future change. In one such study, local fluctuations were used to study the impacts of potential global warming on the runoff portion of the hydrologic cycle (Karl and Riebsame, 1989).

The greater variety in processes and relationships at a more local scale represents an opportunity for learning more about the complex causes and consequences of global change.

Perspective

Differences in perspective between macro and micro provide many examples of situations where researchers looking at an issue top-down come to different conclusions from those looking at that same issue bottom-up. A classic case is analyses of the cost of energy efficiency improvements and other approaches to limiting carbon dioxide emissions, where macroscale economic work has often estimated a significant net cost to the U. S. national economy, while microscale work in many regions of the world has consistently estimated a net benefit. Similarly, macroscale analysis of climate change impacts on agriculture finds little net loss in productivity, with one region's gains accounting for another's losses, while microlevel studies identify as especially vulnerable developing country smallholder agriculturists, pastoralists, wage laborers, urban poor, refugees, and other destitute groups. Where global change is concerned, a focus on a single scale tends to emphasize processes, information and parties influential at that scale, raising the possibility of misunderstanding cause and effect by missing the relevance of processes that operate at a different scale. Focusing exclusively at a local scale can lead to explanations in terms of local causes when some important determinants lie in processes at larger regional and global scales. Focusing exclusively on a larger scale can lead to ready generalizations that are much too general.

Scale in Integrated Global Climate Modeling

The dominant paradigm in integrated global climate modeling works from the top down, beginning with a global atmospheric circulation model which is elaborated to add more hydrological, oceanographic and vegetation features. The expanded model gives rough estimates of impacts on climate which are used to simulate possible impacts on nature and human activity. Potentials for mitigation, beginning with inventories of technologies and socioeconomic instruments are fed into an integrated model to get a sense of the costs and benefits of alternative courses of action. There are at least 15 major integrated assessments underway worldwide. A common characteristic of these models is their low resolution; two-thirds of them have a geographic specificity of either the entire globe or of continents.

Serious mismatches in scale are apparent in the results of such efforts. Changes in atmospheric driving forces are projected at a global or major regional scale, while source and sink changes due to emissions and land use changes are essentially local (but data are scarce at a local scale). Further, there is a relatively poor fit between the scale of climate change forecasting and the scale at which weather is experienced. To date, such efforts have not provided much assistance in choosing response strategies; there has been little space-specific study of appropriate responses, reflecting a grave mismatch between availability and need. This is especially pronounced regarding adaptation potentials.

Relevant Current Global Change Research

In response to these problems, Wilbanks reviewed some scale-related directions in integrated global change research. The central challenges are to downscale the current top-down research paradigm to make it more useful, to incorporate the differences in perspective between top-down and bottom-up studies, and to improve understanding of what local areas and actors actually do and might want to do about global change.

Changes in atmospheric driving forces are projected at a global or major regional scale, while source and sink changes due to emissions and land use changes are essentially local.

In down-scaling the dominant top-down research paradigm, work is underway to improve the geographic and topical richness of global climate models, to move downscale and to cross scales more carefully, to make linkages in the integrated assessment models more relevant to local and regional concerns, and to improve the forecasts of regional (if not local) impacts and thereby encourage suitable responses. For atmospheric driving forces, the U. S.'s Country Studies program and EPA's state estimates are examples of this. For responses to climate change, the regional impacts workshops being run by the U. S. Global Change Research Program are a demonstration of this direction (see Session Two in this report). An effort to compute place-specific impacts of global climate change can be seen in a study of global agriculture by Rosenzweig, Parry and Fisher (1995). Based on projections from three global climate models, they estimate potential grain yields under several plausible scenarios for climate change, suggesting that a doubling of atmospheric carbon dioxide concentration will cause decreases in global food production.

Making the results of integrated assessments of global climate change more useful to decision makers depends fundamentally on making the results more specific to the concerns of localities and regions, the scale at which many policies are enacted and decisions made. The National Center for Integrated Assessment Research at Carnegie Mellon University, for instance, is making an effort to downscale the results of integrated assessment models. How to communicate these results is also part of the challenge, and this is the subject of research by Clark and colleagues at Harvard University.

For some perspective on local action, Wilbanks pointed to conclusions reached by a National Academy of Sciences/National Research Council committee in the 1980s. Of central importance to local action is the credibility of information, which is related to trust in intermediaries and often related to direct personal contact. The importance of local freedom and control in determining the acceptance of risk and uncertainty was also stressed. Issues affecting local action include getting on the agenda, mobilizing action, obtaining resources, maintaining policies and programs, spreading ideas and experiences among local areas, and international linkages. Comparative case studies of lessons learned and channels of communication among local areas were also seen as important.

Making the results of integrated assessments of global climate change more useful to decision makers depends fundamentally on making the results more specific to the concerns of localities and regions.

Tentative Conclusions About Scale in Integrated Assessments

In summary, Wilbanks offered some preliminary conclusions about scale in the integrated assessment process:

 

References

Karl, T. R., and W. R. Riebsame, 1989. The impact of decadal fluctuations in mean precipitation and temperature on runoff: A sensitivity study over the United States. Climatic Change, 15:423-447.

Kates, Robert W. and Viola Haarmann, 1992. Where the Poor Live: Are the Assumptions Correct?, Environment: 34:4-11, 25-28.

Rosenzweig, C. M., L. Parry, and G. Fischer, 1995. "World Food Supply," in As Climate Changes: International Impacts and Implications , K. M. Strzepek and J. B. Smith, eds., Cambridge University, Cambridge, UK, pp. 27-56.

Wilbanks, Thomas J., and Robert W. Kates, 1997. "Global Change in Local Places: How Scale Matters," Discussion Paper No. 1, Global Change in Local Places Project, Association of American Geographers.

Up-scaling and down-scaling challenges meet in determining the most appropriate scale for integrated assessment, which will vary according to the question being asked but will often be an intermediate scale.
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