Building Consensus in Environmental Impact Assessment Through Multicriteria Modeling and Sensitivity Analysis LUIS A. BOJO ´ RQUEZ-TAPIA* School of Natural Resources Biological Sciences East, RM. 207 University of Arizona Tuscon, Arizona 85721, USA SALVADOR SA ´ NCHEZ-COLON ARTURO FLORE MARTINEZ Departmentó de Botanica, Escuela Nacional de Ciencias Biológicas Instituto PolitØcnico Nacional Carpio y Plan de Ayala SFN 11340, Mexico, DF ABSTRACT / Multicriteria decision analysis (MCDA) increasingly is being applied in environmental impact assessment (EIA). In this article, two MCDA techniques, sto- chastic analytic hierarchy process and compromise pro- gramming, are combined to ascertain the environmental impacts of and to rank two alternative sites for Mexico CityÕs new airport. Extensive sensitivity analyses were performed to determine the probability of changes in rank ordering given uncertainty in the hierarchy structure, decision criteria weights, and decision criteria performances. Results dem- onstrate that sensitivity analysis is fundamental for attaining consensusamongmembersofinterdisciplinaryteamsandfor settling debates in controversial projects. It was concluded that sensitivity analysis is critical for achieving a transparent and technically defensible MCDA implementation in contro- versial EIA. Environmental impact assessment (EIA) is increas- ingly at the center of public debate regarding the implementation of large-scale infrastructure projects. EIA is a systematic study aimed at appraising the likely effects of development projects on the environment. Under this context, EIA entails the consideration of the relevant environmental issues so that authorities can make well-informed decisions concerning project approval and, if appropriate, set the conditions for the mitigation of the foreseeable impacts (Hollick 1980; Ortolano 1997). In addition, EIA also plays a crucial role in the decision-making process of projects that involve conflicting issues with high political content, such as site selection in large-scale infrastructure planning. In controversial cases, different stakeholders bring into play their own perspectives and information to either support or oppose a project. In such cases, an EIA must supply the technical and scientific arguments needed for settling disputes among the stakeholders and prevent ideologically based opinions from influ- encing the decision-making process (Lawrence 2000; Leknes 2001). Contentious infrastructure projects raise some con- sequential issues in EIA. An EIA requires precise defi- nitions of standards, goals, and visions related to the notion of ‘‘environmental quality,’’ yet, environmental quality is an abstraction generated by value-laden and subjective reasoning (Hull and others 2003), so such definitions are always relative to specific interests and preconceptions. Furthermore, although the subjectiv- ity of the stakeholders can be easily recognized, it is not often acknowledged that the judgments of the experts themselves can reflect similar biases (Beattie 1995; Kontic 2000). In contrast, a stakeholder may contest an EIA if the outcome of the assessment does not support a particular stance, claiming that the analyses are incomplete, flawed, and biased (Beattie 1995; Crowfoot and Wondolleck 1990; Wondolleck, 1985). Therefore, an EIA should consist of a thorough appraisal of im- pacts relative to antagonistic conceptions of environ- mental quality, including those generated even by vested interests, deep-seated emotions, and subjective reasoning (Rauschmayer 2001). Although the existence of opposing viewpoints about a project underscores the need for an unbiased EIA, identifying which environmental factors should be included in the analysis demands considerable effort KEY WORDS: Airport; Analytic hierarchy process; Compromise programming; Conflict resolution; Environmental impact assessment; Mexico; Participatory Planning; Sensitivity analysis; Suitability Analysis; Uncertainty Published online August 3, 2005. *Author to whom correspondence should be addressed; email: l_boj@ yahoo.com Environmental Management Vol. 36, No. 3, pp. 469–481 ª 2005 Springer Science+Business Media, Inc. DOI: 10.1007/s00267-004-0127-5