Eugene A. Rosa

STIRPAT, IPAT and ImPACT: analytic tools for unpacking the driving forces of environmental impacts

Abstract Despite the scientific consensus that humans have dramatically altered the global environment, we have a limited knowledge of the specific forces driving those impacts. One key limitation to a precise understanding of anthropogenic impacts is the absence of a set of refined analytic tools. Here we assess the analytic utility of the well-known IPAT identity, the newly developed ImPACT identity, and their stochastic cousin, the STIRPAT model. We discuss the relationship between these three formulations, their similar conceptual underpinnings and their divergent uses. We then refine the STIRPAT model by developing the concept of ecological elasticity (EE). To illustrate the application of STIRPAT and EE, we compute the ecological elasticities of population, affluence and other factors for cross-national emissions of carbon dioxide (CO2) from fossil fuel combustion and for the energy footprint, a composite measure comprising impacts from fossil fuel combustion, fuel wood, hydropower and nuclear power. Our findings suggest that population has a proportional effect (unitary elasticity) on CO2 emissions and the energy footprint. Affluence monotonically increases both CO2 emissions and the energy footprint. However, for the energy footprint the relationship between affluence and impact changes from inelastic to elastic as affluence increases, while for CO2 emissions the relationship changes from elastic to inelastic. Climate appears to affect both measures of impact, with tropical nations having considerably lower impact than non-tropical nations, controlling for other factors. Finally, indicators of modernization (urbanization and industrialization) are associated with high impacts. We conclude that the STIRPAT model, augmented with measures of ecological elasticity, allows for a more precise specification of the sensitivity of environmental impacts to the forces driving them. Such specifications not only inform the basic science of environmental change, but also point to the factors that may be most responsive to policy.

Footprints on the Earth: The Environmental Consequences of Modernity

Growing evidence demonstrating clear threats to the sustainability of the ecosystems supporting human societies has given rise to a variety of sociological theories of human-environment interactions. These environmental impact theories fall into three general perspectives: human ecology modernization and political economy. These theories however have not been empirically tested in a common analytic framework. Here a framework that relies on ecological principles is adopted and modified. Using a revised stochastic formulation of that framework and the most comprehensive measure of environmental impact to date-the ecological footprint-the factors driving the environmental impacts of societies are assessed. The overall findings support the claims of human ecologists partially support the claims of political economists and contradict the claims of modernization theorists. Basic material conditions such as population economic production urbanization and geographical factors all affect the environment and explain the vast majority of cross-national variation in environmental impact. Factors derived from neo-liberal modernization theory such as political freedom civil liberties and state environmentalism have no effect on impacts. Taken together these findings suggest societies cannot be sanguine about achieving sustainability via a continuation of current trends in economic growth and institutional change. (authors)

Driving the human ecological footprint

This comparative analysis shows that population size and affluence are the principal drivers of anthropogenic environmental stressors, while other widely postulated drivers (eg urbanization, economic structure, age distribution) have little effect. Similarly, increased education and life expectancy do not increase environmental stressors, suggesting that some aspects of human well-being can be improved with minimal environmental impact. Projecting to 2015, we suggest that increases in population and affluence will likely expand human impact on the environment by over one-third. Countering these driving forces would require increases in the efficiency of resource use of about 2% per year.

Key Challenges to Ecological Modernization Theory Institutional Efficacy, Case Study Evidence, Units of Analysis, and the Pace of Eco-Efficiency

We raise four challenges to the claim of ecological modernization theory (EMT) that continued modernization is necessary for ecological sustainability. First, EMT needs to go beyond merely demonstrating that societies modify their institutions in reaction to environmental problems and show that such modifications lead to ecological improvements. Second, EMT must show that late stages of modernizing processes lead to the ecological transformation of production and consumption at relatively high frequency. Third, EMT must demonstrate that industries or firms that are reducing their direct impact on the environment are not contributing to the expansion of negative impacts by other industries or firms. Fourth, EMT must show not only that economies are becoming more resource efficient but also that the pace of increase in efficiency exceeds the pace of increase in overall production. In this article, we review the existing evidence and find that EMT has insufficiently addressed these four issues.

The Future of Nuclear Power: Value Orientations and Risk Perception

Since the turn of the 21st century, there has been a revival of interest in nuclear power. Two decades ago, the expansion of nuclear power in the United States was halted by widespread public opposition as well as rising costs and less than projected increases in demand for electricity. Can the renewed enthusiasm for nuclear power overcome its history of public resistance that has persisted for decades? We propose that attitudes toward nuclear power are a function of perceived risk, and that both attitudes and risk perceptions are a function of values, beliefs, and trust in the institutions that influence nuclear policy. Applying structural equation models to data from a U.S. national survey, we find that increased trust in the nuclear governance institutions reduces perceived risk of nuclear power and together higher trust and lower risk perceptions predict positive attitudes toward nuclear power. Trust in environmental institutions and perceived risks from global environmental problems do not predict attitudes toward nuclear power. Values do predict attitudes: individuals with traditional values have greater support for, while those with altruistic values have greater opposition to, nuclear power. Nuclear attitudes do not vary by gender, age, education, income, or political orientation, though nonwhites are more supportive than whites. These findings are consistent with, and provide an explanation for, a long series of public opinion polls showing public ambivalence toward nuclear power that persists even in the face of renewed interest for nuclear power in policy circles.

Tracking the Anthropogenic Drivers of Ecological Impacts

Abstract Despite the pivotal role human factors (anthropogenic drivers) are presumed to play in global environmental change, substantial uncertainties and contradictory conclusions about them continue. We attempt to further discipline the human factors issue by estimating the effects of two anthropogenic drivers, population and affluence, on a wide variety of global environmental impacts, including greenhouse gas emissions, emissions of ozone depleting substances, and the ecological footprint. Population proportionately increases all types of impacts examined. Affluence typically increases impacts, but the specific effect depends on the type of impact. These findings refocus attention on population and material affluence as principal threats to sustainability and challenge predictions of an ameliorating effect of rising affluence on impacts.

Cognitive Representation of Risk Perceptions A Comparison of Japan and the United States

An impressive body of research in the psychometric tradition has demonstrated systematic biases in the way Americans perceive risks associated with technologies, substances, and activities. The consistency of the findings has raised the question of whether these biases are culturally specific or reflective of more fundamental human thought processes. Do people in different cultures perceive technological and other risks differently or similarly? An answer to the question is also important to the development of effective communication strategies and international policies for addressing global risks. Recent empirical research to address the question has used psychometric techniques to-assess the risk perceptions of samples in Hungary, Norway, and Hong Kong. The research presented here, building and improving on the previous cross-cultural work, is a comparison of risk perceptions between American and Japanese people. The results from the concurrently collected perception data indicate both striking similarities and differences in the ways Americans and Japanese perceive risks.

Climate Change and Society Speculation, Construction and Scientific Investigation

This article traces the long intellectual history that seeks to understand the recursive relationship between variations in the Earths climate and variations in social structure and cultural practices. Contemporary sociological investigations of this theme have evolved along two paths: the neoidealistic orientation of social constructivism and a neo-realist orientation comprising two complementary approaches. Both orientations are explicated and evaluated, leading to a conclusion that provides programmatic directions.

The Ecological Footprint Intensity of National Economies

At least three perspectives—industrial ecology (IE), ecological modernization theory (EMT), and the “environmental Kuznets curve” (EKC)—emphasize the potential for sustainability via refinements in production systems that dramatically reduce the environmental impacts of economic development. Can improvements in efficiency counterbalance environmental impacts stemming from the scale of production? To address this question we analyze cross-national variation in the ecological footprint (EF) per unit of gross domestic product (GDP). The EF is a widely recognized indicator of human pressure on the environment. The EF of a nation is the amount of land area that would be required to produce the resources it consumes and to absorb the wastes it generates. The most striking finding of our analyses is that there is limited variation across nations in EF per unit of GDP. This indicates limited plasticity in the levels of EF intensity or eco-efficiency among nations, particularly among affluent nations. EF intensity is lowest (ecoefficiency is highest) in affluent nations, but the level of efficiency in these nations does not appear to be of sufficient magnitude to compensate for their large productive capacities. These results suggest that modernization and economic development will be insufficient, in themselves, to bring about the ecological sustainability of societies.

Bridging Environmental Science with Environmental Policy: Plasticity of Population, Affluence, and Technology

Objective. Sound environmental policy is fully dependent upon sound science. However, we have little scientific knowledge of the driving forces behind environmental change. We use the well‐known I = PAT formulation (environmental impacts are the multiplicative product of population, affluence, and technology) as a framework to assess the relative impacts of driving forces. Methods. We introduce the concept ofplasticity—the potential for each factor to vary, particularly because of purposive human action (e.g., policy)—to fine tune our understanding of how each factor can influence different impacts. We illustrate plasticity by assessing each driving force for a variety of environmental impacts. Results. We demonstrate that population, affluence, and technology have different potentials for mitigating different types of impacts and that no one factor is of greater importance than the others. Conclusions. We conclude that plasticity measures can guide policymakers toward identifying and prioritizing those environmental problems most responsive to policy solution.