land cover, and resource use with its associated waste products. But a key feature of most regions is that more than one driving force is changing simultaneously. Consequently, most locations are characterized by multiple stresses. The effect of a combination of environmental stresses is seldom simply additive. Rather, they often produce amplified or damped responses, unexpected responses, or threshold responses in environmental systems. Multiple, cumulative, and interactive stresses are clearly the most difficult to understand and hence the most difficult to manage.

In contrast, most research, analysis, and policy are based on studies that examine discrete parts of these complex problems. Basically, earth and environmental sciences tend to focus on cause and effect, where we seek to understand how a specific element of the system may respond to a specific change or perturbation (e.g., acid rain on lake fisheries). The lack of an ability to assess the response of the system to multiple stresses limits our ability to assess the impacts of specific human perturbations, to assess advantages and risks, and to enhance economic and societal well-being in the context of global, national, and regional stewardship.

However, the problem is not limited simply to moving from analysis of discrete parts of complex problems to a more comprehensive analysis.

First, economic vitality and societal well-being are increasingly dependent on combining global, regional, and local perspectives. A “place-based” imperative for environmental research stems from the importance of human activities on local and regional scales, the importance of multiple stresses on specific environments, and the nature of the spatial and temporal linkages between physical, biological, chemical, and human systems. We find the strongest intersection between human activity, environmental stresses, earth system interactions and human decision making in regional analysis coupled to larger spatial scales.

Second, a decade of research on greenhouse gas emissions, ozone depletion, and deforestation has clarified many critical unanswered questions. However, the last decade of effort has also revealed a number of challenges, most notably the challenge of creating integrated global observational capabilities and the computational and scientific limitations inherent in creating a truly integrated, global, coupled system modeling capability suitable for assessing impacts and adaptations. These problems are noteworthy in global change science, but they become intractable at the scales of human decision making. A major part of the problem is simply a matter of scale combined with the sheer information required to combine physical, biological, chemical, and human systems if the framework is global. For example, whereas a global integrated observing system is challenging but tractable and plays a fundamental role on the scale of a global circulation model, it collapses under its own weight at higher spatial resolutions if we demand a truly comprehensive data system involving the host of observations spanning biology, hydrology, soils, weather, etc., required to address problems at

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