A policy decision tool for integrated environmental assessment

Abstract

Abstract The establishment of the Intergovernmental Panel on Climate Change (IPCC) in 1988 and the U.S. Global Change Research Program in 1990 led to the extensive study of complex global change during the past decade, often referred to as integrated assessment (IA). Integrated assessment models (IAMs) are analytical tools for conducting integrated assessments. IAMs include a variety of quantitative models as well as scenario-based approaches, which are more recent attempts to integrate social systems and values into integrated assessment. However, social systems and values change in response to results from policy actions, or in response to new information obtained after such actions are taken. Therefore, full integration of scientific models and concerns about social values can only be achieved in models that incorporate decisions, actions, and information gathered from such actions. It is the inadequate incorporation of the consequences of sequential policy decisions (such as the elimination of currently available policy choices, or the creation of new ones) that limits the usefulness of IAMs in informing policy decisions. This paper proposes the use of Markov decision processes (MDPs) as a policy decision tool for integrated assessment and demonstrates the utility of this approach using a simple numerical example. In addition to proposing a MDP decision model, this paper advocates adaptive management (AM) as the decision-making process to embed the decision model. It is argued that AM is inherently suited as a decision process for integrated assessment, particularly due to its key tenets of experimentalism (“learning by doing”), multi-scalar analysis and place-sensitivity. Thus, this paper makes an important contribution by enhancing the usefulness of integrated assessment as a policy decision tool, rather than merely an analytical one.