• Structural complexity: choices affect phenomena that operate at multiple scales; decision-making entities also exist at multiple scales, not necessarily matched to those of the phenomena; and many different kinds of expertise are required to understand the issues.

  • Multiple, conflicting, and uncertain values: people affected by the choices have deeply held values often tied to spiritual, cultural, stewardship, or equity concerns that they are unwilling to negotiate or trade off; people differ in their value priorities; and sometimes their values seem to shift unexpectedly.

  • Long time horizons: the consequences of choices made now may extend for decades or longer.

  • Open-access structure: it is often difficult to exclude people from using or polluting a resource, putting that resource at considerable risk of overuse and decline (see Chapter 3).

  • Incomplete and uncertain knowledge: the consequences of choice options may be unknown or in dispute among scientists; they may also be dependent on ongoing processes of social or environmental changes that are also little understood.

  • High stakes: the long-term implications of the wrong choice for environment and society may be profound.

  • Time pressure: decisions must be made without waiting for scientific certainty or agreement on values.

These points are well recognized by observers of environmental decision processes (e.g., Funtowicz and Ravetz, 1992; National Research Council, 1996; Dietz and Stern, 1998; Renn, 2003). A further challenge is to address the linked nature of environmental processes and environmental decisions across time scales, physical scales, and institutional scales. Decisions made at one scale can be transformed or undermined by processes at other scales, which must therefore be taken into account. Researchers have only recently given serious consideration to this challenge to environmental decision making and management (Cash and Moser, 2000; Young, 2002; Berkes, 2002; also see Chapter 3).

In addition, environmental choices are affected by decision makers’ attention to various environmental or other aspects of the choices. Individuals’ apparent preferences shift depending on how choices are framed and on their interpretations of and affective reactions to information (Tversky and Kahneman, 1981; Kahneman, Ritov, Jacowitz, and Grant, 1993; Slovic, 1995), and the apparent priorities of organizations and governments shift as a function of how interested parties shape decision agendas (Kingdon, 1987).

Decisions of such difficulty require a variety of inputs. Elected representatives, who are normally entrusted with making value choices, rarely



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