Toward a Coherent Theory of Environmentally Significant Behavior.

This article develops a conceptual framework for advancing theories of environmentally significant individual behavior and reports on the attempts of the author's research group and others to develop such a theory. It discusses definitions of environmentally significant behavior; classifies the behaviors and their causes; assesses theories of environmentalism, focusing especially on value-belief-norm theory; evaluates the relationship between environmental concern and behavior; and summarizes evidence on the factors that determine environmentally significant behaviors and that can effectively alter them. The article concludes by presenting some major propositions supported by available research and some principles for guiding future research and informing the design of behavioral programs for environmental protection.

Recent developments in theory and research give hope for building the understanding needed to effectively alter human behaviors that contribute to environmental problems. This article develops a conceptual framework for the theory of environmentally significant individual behavior, reports on developments toward such a theory, and addresses five issues critical to building a theory that can inform efforts to promote proenvironmental behavior.

Environmentally significant behavior can reasonably be defined by its impact: the extent to which it changes the availability of materials or energy from the environment or alters the structure and dynamics of ecosystems or the biosphere itself (see Stern, 1997). Some behavior, such as clearing forest or disposing of household waste, directly or proximally causes environmental change (Stern, Young, & Druckman, 1992). Other behavior is environmentally significant indirectly, by shaping the context in which choices are made that directly cause environmental change (e.g., Rosa & Dietz, 1998; Vayda, 1988). For example, behaviors that affect international development policies, commodity prices on world markets, and national environmental and tax policies can have greater environmental impact indirectly than behaviors that directly change the environment.

Through human history, environmental impact has largely been a by-product of human desires for physical comfort, mobility, relief from labor, enjoyment, power, status, personal security, maintenance of tradition and family, and so forth, and of the organizations and technologies humanity has created to meet these desires. Only relatively recently has environmental protection become an important consideration in human decision making. This development has given environmentally significant behavior a second meaning. It can now be defined from the actor's standpoint as behavior that is undertaken with the intention to change (normally, to benefit) the environment. This intent-oriented definition is not the same as the impact-oriented one in two important ways: It highlights environmental intent as an independent cause of behavior, and it highlights the possibility that environmental intent may fail to result in environmental impact. For example, many people in the United States believe that avoiding the use of s pray cans protects the ozone layer, even though ozone-destroying substances have been banned from spray cans for two decades. The possible discrepancy between environmental intent and environmental impact raises important research questions about the nature and determinants of people's beliefs about the environmental significance of behaviors.

Both definitions of environmentally significant behavior are important for research but for different purposes. It is necessary to adopt an impact-oriented definition to identify and target behaviors that can make a large difference to the environment (Stern & Gardner, 1981a). This focus is critical for making research useful. It is necessary to adopt an intent-oriented definition that focuses on people's beliefs, motives, and so forth in order to understand and change the target behaviors.

Types of Environmentally Significant Behavior

Much early research on proenvironmental behavior presumed it to be a unitary, undifferentiated class. More recently it has become clear that there are several distinct types of environmentally significant behavior and that different combinations of causal factors determine the different types.

Environmental Activism

Committed environmental activism (e.g., active involvement in environmental organizations and demonstrations) is a major focus of research on social movement participation. This research provides detailed analysis of the "recruitment" process through which individuals become activists (McAdam, McCarthy, & Zald, 1988).

Nonactivist Behaviors in the Public Sphere

Recently, the social movement literature has pointed to nonactivists' support of movement objectives as another important class of behavior (Zald, 1992). Public opinion researchers and political scientists sometimes examine such behavior, but relatively little research has been done to classify the behaviors into coherent subtypes. It seems reasonable as a first approximation to distinguish between more active kinds of environmental citizenship (e.g., petitioning on environmental issues, joining and contributing to environmental organizations) and support or acceptance of public policies (e.g., stated approval of environmental regulations, willingness to pay higher taxes for environmental protection). My colleagues and I have found empirical support for distinguishing these types from each other and from activism (Dietz, Stern, & Guagnano, 1998; Stern, Dietz, Abel, Guagnano, & Kalof, 1999). Although these behaviors affect the environment only indirectly, by influencing public policies, the effects may be la rge, because public policies can change the behaviors of many people and organizations at once. An important feature of public-sphere behaviors, including activism, is that environmental concerns are within awareness and may therefore be influential.

Private-Sphere Environmentalism

Consumer researchers and psychologists have focused mainly on behaviors in the private sphere: the purchase, use, and disposal of personal and household products that have environmental impact. It is useful to subdivide these according to the type of decision they involve: the purchase of major household goods and services that are environmentally significant in their impact (e.g., automobiles, energy for the home, recreational travel), the use and maintenance of environmentally important goods (e.g., home heating and cooling systems), household waste disposal, and "green" consumerism (purchasing practices that consider the environmental impact of production processes, for example, purchasing recycled products and organically grown foods). Making such distinctions has revealed that some types of choice, such as infrequent decisions to purchase automobiles and major household appliances, tend to have much greater environmental impact than others, such as changes in the level of use of the same equipment: the distinction between efficiency and curtailment behaviors (Stern & Gardner, 1981a, 1981b). Private-sphere behaviors may also form coherent clusters empirically (e.g., Bratt, 1999a), and different types of private-sphere behavior may have different determinants (e.g., Black, Stern, & Elworth, 1985). Private-sphere behaviors are unlike public-sphere environmentalism in that they have direct environmental consequences. The environmental impact of any individual's personal behavior, however, is small. Such individual behaviors have environmentally significant impact only in the aggregate, when many people independently do the same things.

Other Environmentally Significant Behaviors

Individuals may significantly affect the environment through other behaviors, such as influencing the actions of organizations to which they belong. For example, engineers may design manufactured products in more or less environmentally benign ways, bankers and developers may use or ignore environmental criteria in their decisions, and maintenance workers' actions may reduce or increase the pollution produced by manufacturing plants or commercial buildings. Such …