From comparative risk assessment to multi-criteria decision analysis and adaptive management: Recent developments and applications I. Linkov a, ⁎ , F.K. Satterstrom b , G. Kiker c , C. Batchelor d , T. Bridges d , E. Ferguson d a Intertox Inc., 83 Winchester Street, Suite 1, Brookline, MA 02446, USA b Cambridge Environmental Inc., 58 Charles Street, Cambridge, MA 02141, USA c University of Florida, Gaineville, FL 32611, USA d U.S. Army Engineer Research and Development Center, Environmental Laboratory, 3909 Halls Ferry Rd, Vicksburg, MS 39180, USA Available online 14 August 2006 Abstract Environmental risk assessment and decision-making strategies over the last several decades have become increasingly more sophisticated, information-intensive, and complex, including such approaches as expert judgment, cost–benefit analysis, and toxicological risk assessment. One tool that has been used to support environmental decision-making is comparative risk assessment (CRA), but CRA lacks a structured method for arriving at an optimal project alternative. Multi-criteria decision analysis (MCDA) provides better-supported techniques for the comparison of project alternatives based on decision matrices, and it also provides structured methods for the incorporation of project stakeholders' opinions in the ranking of alternatives. We argue that the inherent uncertainty in our ability to predict ecosystem evolution and response to different management policies requires shifting from optimization-based management to an adaptive management paradigm. This paper brings together a multidisciplinary review of existing decision-making approaches at regulatory agencies in the United States and Europe and synthesizes state-of- the-art research in CRA, MCDA, and adaptive management methods applicable to environmental remediation and restoration projects. We propose a basic decision analytic framework that couples MCDA with adaptive management and its public participation and stakeholder value elicitation methods, and we demonstrate application of the framework to a realistic case study based on contaminated sediment management issues in the New York/New Jersey Harbor. © 2006 Elsevier Ltd. All rights reserved. Keywords: Comparative risk assessment; Decision analysis; Adaptive management; Risk analysis; Sediments 1. Introduction: comparative risk assessment and evolving decision analysis methodologies Risk management of environmental projects requires balanc- ing scientific findings with multi-faceted input from many stakeholders with different values and objectives. In such instances, systematic decision analysis tools are an appropriate method to solve complex technical and behavioral issues (McDaniels, 1999). Regardless of the specific project, risk managers typically have four types of information that are used to make decisions: 1) the results of modeling and monitoring studies, 2) risk analysis, 3) cost or cost–benefit analysis, and 4) stakeholder preferences (Fig. 1a). These four types of information range from extremely quantitative to extremely qualitative, and structured information about stakeholder preferences may not be presented to decision-makers at all. In cases where the decision- maker does receive information on stakeholder preferences, the information may be handled in a subjective manner that exacerbates the difficulty of defending the decision process as reliable or fair. Moreover, where structured approaches to combining the four categories of information are employed, they may be perceived as lacking the flexibility to adapt to localized concerns or faithfully represent minority viewpoints. A systematic method of combining quantitative and qualitative inputs from scientific studies of risk, cost and cost–benefit analyses, and stakeholder views has yet to be fully developed for environmental decision-making. As a result, decision-makers often do not optimally use all available and useful information in choosing between identified project alternatives. In response to these decision-making challenges, some regulatory agencies and environmental managers have moved toward more integrative decision analytic processes, such as comparative risk assessment (CRA) or multi-criteria decision Environment International 32 (2006) 1072 – 1093 www.elsevier.com/locate/envint ⁎ Corresponding author. Tel.: +1 617 233 9869. E-mail address: ilinkov@intertox.com (I. Linkov). 0160-4120/$ - see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.envint.2006.06.013