Local-Global Linkages Research Paper

Pursuing understandings of such linkages is complicated by the fact that processes at one spatial scale tend to be studied by different communities of scholars than processes at another scale. The respective literatures speak different academic languages, arise from different bodies of theory, and are accustomed to very different units of measurement, even when the subject matter is within a single discipline. When, as is often the case, the linkages cross the boundaries of disciplines, the challenge is much greater—and less often attempted as a matter of careful research rather than qualitative assessment by diverse panels of experts.

The reality, of course, is that global changes in climate, environment, economies, populations, institutions, and cultures converge in localities; and their impacts play out at local and regional scales. At the same time, global changes result from an aggregation of decisions, actions, innovations, mutations, and other changes that arise in specific localities. Examples of the interplay between global and local scales range from AIDS to ecotourism. Macroscale and microscale are linked intrinsically, and neither can be fully understood without considering the other.

1. How Scale Matters

In understanding environmental systems, the issue of global–local linkages would be relatively insignificant if the local scale were merely microglobal, in other words if a phenomenon or process studied at any one scale could be expected to tell the observer essentially the same thing as study at any other scale. There are a number of reasons, however, why scale matters and why understanding linkages between scales is therefore an important part of the search for knowledge (Wilbanks and Kates 1999).

Several of the reasons have to do with how the world works. First of all, the forces that drive environmental systems arise from different domains of nature and society. For example, population ecology operates at a smaller geographic scale than national or global demographic patterns (Clark 1985). Within this universe of different domains, local and regional domains relate to global ones in two general ways: systemic and cumulative (Turner et al. 1990). Systemic changes involve fundamental changes in the functioning of a global system, such as effects of emissions of ozone-depleting gases on the stratosphere, which may be triggered by local actions (and certainly may affect them) but which transcend simple additive relationships at a global scale. Cumulative changes result from an accumulation of localized changes, such as groundwater depletion or species extinction; the resulting systemic changes are not global, although their effects may have global significance. A second reason that scale can matter is that the scale of agency—the direct causation of actions—is often intrinsically localized, while at the same time such agency takes place in the context of structure: a set of institutions and other regularized, often formal relationships whose scale is regional or global. Land use decisions are a familiar example. This kind of local–global linkage is especially important where environmental impact mitigation actions are concerned, analogous to hazards behavior. A third reason that scale can matter is that the driving forces behind environmental change involve interactions of processes at different locations and areal extents and different time scales, with varying effects related to geographical and temporal proximity and structure. Looking only at a local scale can miss some of these interactions, as can looking only at a global scale. For instance, geographers have shown that processes of change involve patterns of spatial diffusion that can be generalized, and ecological modelers such as Holling have found that managed biomes are characterized by landscapes with lumpy geometries and lumpy temporal frequencies related to the size and speed of process interactions, shaped by the fact that processes operating at different scales tend to show faster or slower dynamics (Holling 1995).

Several additional reasons have to do with the how we learn about the world. One of the strongest is the argument that complex relations among environmental, economic, and social processes that underlie environmental systems are too complex to unravel at any scale beyond the local. A second reason is that a portfolio of observations at a detailed scale is almost certain to contain more variance than observations at a very general scale, and the greater variety of observed processes and relationships and relationships at a more local scale can be an opportunity for greater learning about the substantive questions being asked. For instance, net benefits costs from global climate change vary more widely for small areas than large ones (Fig. 1). A third reason is that research experience in a variety of fields tells us that researchers looking at a particular issue top-down can come to dramatically different conclusions from researchers looking at that very same issue bottom-up. The scale embodied in the perspective can frame the investigation and shape the results, which suggests that full learning requires attention at a variety of scales. As one example, Openshaw and Taylor (1979) have demonstrated that simply changing the scale at which data are gathered can change the correlation between variables virtually from +1 to ‒1.

These reasons, of course, do not mean that global– local linkages are salient for every question being asked about environmental and ecological systems. What they suggest is more modest: that examinations of such systems should normally take time to consider linkages between different scales, geographical and temporal, and whether or not those linkages might be important to the questions at hand. Consider two examples:

(a) Land use change and climate change. Obviously, anthropogenic causes of climate change arise from location-specific activities: points, such as a coalfueled electric power plant; areas, such as a forest or a farming region; and flows, such as interstate highways. Local and regional land use shapes climate change; and reductions in pressures toward climate change are rooted in changes in land uses, although some of the largest contributors occupy relatively small geographical areas. At the same time, climate change affects land use. For instance, it can cause hardwood trees to displace pines or vice versa. It can lead to changes in agricultural cropping patterns. And sea level rise leads to shoreline retreat and coastal land loss. One example of a linkage between the scales is that concerns about impacts at a local level can lead to efforts to promote greenhouse gas emission abatement in order to reduce the likelihood or magnitude of those impacts. An important program of the International Geosphere–Biosphere Program is concerned with land use and land cover change (LUCC), including linkages between very local processes and a variety of larger scales (Turner et al. 1995).

(b) Biodi ersity protection. Likewise, biodiversity protection has both local and very large-scale dimensions. Most endangered species exist within localized ecological niches with a rather narrow tolerance for change. Other than through zoos or gene banks, their protection requires action at a very local level. On the other hand, many of the forces that endanger them, from environmental pollution to economic and demographic growth, arise at a much larger scale. In addition, where species are migratory, their survival depends not only on a single local biosphere but on a viable migration corridor between seasonal biospheres as well, at the scale of a region or beyond.

2. Tracing out the Linkages

Our understanding of global–local linkages in the environmental and ecological sciences is still poorly developed and is a promising subject for further research. As few hypotheses based on rather fragmentary evidence, however, can suggest some directions for discussion.

It appears, for instance, that whether global change is likely to cause local change depends on how significant and discontinuous the global change is, whether localities are substantially subject to external driving forces, and whether global processes are relatively closely linked with local processes. It appears that whether local change is likely to cause global change depends on the magnitude and force of the local change, whether the local change is focused on a key driving force in a global process, and whether the local change either (a) is associated with structures processes for dissemination or (b) is associated cumulatively with similar local changes elsewhere. It appears that whether a global–local link is likely to be disruptive depends on existing stress levels in localities and their adaptability and coping capacity. It also appears that divergences between local and global optimality are affected by mobility, which is clearly increasing in many global networks; in some cases the divergence can be greater where mobility and other adaptation mechanisms are limited, while in others it can be magnified by a loss of control at the local level over the nature and speed of change.

3. Linking the Global and the Local

In seeking to improve the understanding of macro– microscale linkages, a common conceptual approach has been to depict the systems operating at different scales as hierarachies: classes of processes in which each smaller unit is nested within a larger unit, which can be associated with bodies of theory about interactions within and between scales (e.g., Allen and Starr 1982). Examples include ecosystems and economic markets. Such approaches have often been fruitful, but they are often criticized for arbitrarily dividing complex systems into a limited number of levels of ‘organization.’

Current efforts to improve the capacity to trace out, understand, and if appropriate modify linkages between the global and the local in environmental and ecological systems include attention to five central problems:

(a) Downscaling global and other large-scale models to understand issues at a regional or local scale, such as implications of global environmental change. Recognizing the limitations of top-down paradigms based on global or near-global scale modeling, the research community is increasingly active in moving toward more detailed geographic scales and topical richness, using both numerical (i.e., model-based) and empirical (i.e., statistical-based) approaches. Challenges include data availability at detailed scales, the complexity of process relationships as models become more like the real world, and in some cases computational capacity (although advances in computing have reduced this constraint considerably). Appetites on the part of model users for downscaling appear insatiable; as a result, this trend is expected to continue.

(b) Upscaling data from points or very small areas to understand issues at a regional or global scale. Many kinds of data pertinent to macroscale issues are gathered at specific points, ranging from meteorological observations to crop production; but in many cases these data cannot simply be aggregated to estimate larger-scale values, such as regional agricultural production or climate processes. For instance, the data may fail to meet standards for valid sampling, and they may fail to represent stochastic and geographic variability in representing how processes work. As one example, it has been shown that an estimated response to an ‘average’ environment can be a biased predictor of a ‘true’ aggregate response (Templeton and Lawlor 1981).

(c) Integrating top-down and bottom-up perspectives to arrive at a comprehensive understanding. Where downscaling and upscaling come together is when the two approaches are merged to attain an integrated understanding of processes, benefiting from the strengths of both perspectives. This kind of integration is usually done in one of three ways: (i) by converting both perspectives to a common metric, usually a ‘meso’ or intermediate scale such as one-half degree of (equatorial) latitude and longitude (e.g., Easterling 1997); (ii) by comparing the two different answers and adjusting the approach used in arriving at each, iterating until a single answer is derived (applied, for instance, in the integrated environment economy model of the International Institute for Applied Systems Analysis); and (iii) by comparing the two different answers and seeking a meta-understanding, incorporating both perspectives but arriving at a third answer (e.g., the multidisciplinary Susquehanna River Valley study conducted by the Pennsylvania State University: see Abler et al. 2000). In many cases, integration is partly a matter of bridging between analytical styles, for example, top-down models and bottom-up case studies. In addition, it is often a matter of reconciling differences in process assumptions, theoretical foundations, and perceived standards as to what constitutes the best science.

(d) Resolving differences in scales between relevant processes. Because different interacting processes may operate at different scales, for example, between the scale of ecosystems and the scale of governmental units making decisions about them, efforts to incorporate a variety of linkages in a single analysis or action must often confront problems of ‘scale discordance.’ Among the avenues being investigated are adaptive approaches to analysis and management, which permit modifications of the scale as more is learned about the relevant processes and their interactions.

(e) Accounting for cross-scale dynamics. Because so much data collection and analysis occurs at a particular scale, data are often scarce about cross-scale relationships and interactions. Strategies for reducing this gap are being considered through the establishment of richer information infrastructures, especially regarding longitudinal data sets, but assuring continued financial support for data collection structures is a continuing challenge.

Much of this growing effort to improve the understanding of global–local linkages is motivated not only by scientific curiosity but also by social needs to deal with environmental problems such as reducing environmental pollution, coping with possible impacts of global climate change, and responding to threatened losses of ecosystem quality and variety.

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