Programs and Communities

While the definition of sustainability remains open for all to contribute to and participate in, there do seem to be some notions it has come to embody that should not be neglected as the definition coalesces. Among these are the ethical and social dimensions of sustainability. Whether or not it is appropriate, required, or even desirable, concepts like social equity, human rights, ethical sharing of commons, etc. have increasingly come under the umbrella of the sustainability discourse. Even if “sustainability” as a bare word doesn’t imply those things, the concept of sustainable development certainly has taken on those dimensions. That sustainability might be redefined or re-scoped to be a purely environmental or a rigidly scientific endeavor, is not an immediate concern of this paper, though if that were to occur (whether for the sake of simplicity or pragmatics), it should be done explicitly so the ethical sub-discourse can be maintained (indeed, sustained) by some other movement.

This paper proposes a mechanism by which such a migration in terms can be prevented. First, in reviewing the work of Denis Goulet, it shows the solid basis for including an ethical aspect in the sustainability discourse. Second, it points out that Karl-Henrik Robèrt’s highly-lauded and broadly-employed sustainability framework, The Natural Step, is deficient in this area. This deficiency provides the impetus for, finally, proposing a mechanism by which The Natural Step can be extended to include the important social and ethical dimensions of sustainability. This mechanism is based on the capabilities approaches that, in many respects, evolved out of Goulet’s early work. Augmented accordingly, TNS can continue to be used without fear of overlooking the social and ethical aspects of the sustainability discourse.

Maricopa County, Arizona, anchor to the fastest growing megapolitan area in the United States, is located in a hot desert climate where extreme temperatures are associated with elevated risk of mortality. Continued urbanization in the region will impact atmospheric temperatures and, as a result, potentially affect human health. We aimed to quantify the number of excess deaths attributable to heat in Maricopa County based on three future urbanization and adaptation scenarios and multiple exposure variables.

Two scenarios (low and high growth projections) represent the maximum possible uncertainty range associated with urbanization in central Arizona, and a third represents the adaptation of high-albedo cool roof technology. Using a Poisson regression model, we related temperature to mortality using data spanning 1983–2007. Regional climate model simulations based on 2050-projected urbanization scenarios for Maricopa County generated distributions of temperature change, and from these predicted changes future excess heat-related mortality was estimated. Subject to urbanization scenario and exposure variable utilized, projections of heat-related mortality ranged from a decrease of 46 deaths per year (− 95%) to an increase of 339 deaths per year (+ 359%).

Projections based on minimum temperature showed the greatest increase for all expansion and adaptation scenarios and were substantially higher than those for daily mean temperature. Projections based on maximum temperature were largely associated with declining mortality. Low-growth and adaptation scenarios led to the smallest increase in predicted heat-related mortality based on mean temperature projections. Use of only one exposure variable to project future heat-related deaths may therefore be misrepresentative in terms of direction of change and magnitude of effects. Because urbanization-induced impacts can vary across the diurnal cycle, projections of heat-related health outcomes that do not consider place-based, time-varying urban heat island effects are neglecting essential elements for policy relevant decision-making.

Global environmental change and sustainability science increasingly recognize the need to address the consequences of changes taking place in the structure and function of the biosphere. These changes raise questions such as: Who and what are vulnerable to the multiple environmental changes underway, and where? Research demonstrates that vulnerability is registered not by exposure to hazards (perturbations and stresses) alone but also resides in the sensitivity and resilience of the system experiencing such hazards. This recognition requires revisions and enlargements in the basic design of vulnerability assessments, including the capacity to treat coupled human–environment systems and those linkages within and without the systems that affect their vulnerability. A vulnerability framework for the assessment of coupled human–environment systems is presented.

Research on global environmental change has significantly improved our understanding of the structure and function of the biosphere and the human impress on both (1). The emergence of “sustainability science” (2–4) builds toward an understanding of the human–environment condition with the dual objectives of meeting the needs of society while sustaining the life support systems of the planet. These objectives, in turn, require improved dialogue between science and decision making (5–8). The vulnerability of coupled human–environment systems is one of the central elements of this dialogue and sustainability research (6, 9–11). It directs attention to such questions as: Who and what are vulnerable to the multiple environmental and human changes underway, and where? How are these changes and their consequences attenuated or amplified by different human and environmental conditions? What can be done to reduce vulnerability to change? How may more resilient and adaptive communities and societies be built?

Answers to these and related questions require conceptual frameworks that account for the vulnerability of coupled human–environment systems with diverse and complex linkages. Various expert communities have made considerable progress in pointing the way toward the design of these frameworks (10, 11). These advances are briefly reviewed here and, drawing on them, we present a conceptual framework of vulnerability developed by the Research and Assessment Systems for Sustainability Program (http://sust.harvard.edu) that produced the set of works in this Special Feature of PNAS. The framework aims to make vulnerability analysis consistent with the concerns of sustainability and global environmental change science. The case study by Turner et al. (12) in this issue of PNAS illustrates how the framework informs vulnerability assessments.

This research on the early metal ages of the Wadi el-Hasa focuses on settlement systems and attempts to explain how social, economic and political adjustments helped tribal groups survive under natural (i.e., climatic) and anthropogenic (i.e., land degradation, erosion) stress factors. The shifting of subsistence base from agropastoral to pastoral is reflected in site and population densities, diversity of site types, levels of internal complexity, and levels of social organization via the presence of large settlements, like villages, which acted as economic and administrative centers emerge as risk reduction mechanisms.

The cycles of abandonment and resettlement are evaluated within the concept of social reorganization and such changes are assessed as parts of economic revitalization attempts. The social changes that emerge from such shifts are evaluated from the perspective of the scale-free networks modeled and tested through statistical methods, such as ANOVA, for spatial and temporal patterns, while patterns of land use and the impacts of changing climate and anthropogenic activities are evaluated with GIS.

Following the dimorphic society and heterarchic social organization concepts, the discussion emphasizes that tribal groups adjust population density, range and intensity of activities in marginal landscapes, like the Hasa, in order to prevent environmental degradation. These patterns may change once these marginal landscapes are integrated to more complex social organizations. Although this takes place in the Hasa during the Iron Age, the research results imply that environmental degradation did not take place possibly due to the continuation of extensive subsistence patterns, along with the emergence of the long-distance caravan trade as a major economic incentive.