TowardsanIntegratedFrameworkforDevelopment andEnvironmentPolicy:TheDynamicsof EnvironmentalKuznetsCurves MAJIDEZZATI Resources for the Future, Washington, DC, USA, and World Health Organization, Geneva, Switzerland BURTONH.SINGER Princeton University, NJ, USA and DANIELM.KAMMEN * University of California, Berkeley, USA Summary. Ð EnvironmentalKuznetscurvesEKCs)haverecentlyreceivedconsiderableattention in development and environment policy. But little is known on how the interaction between ecologicalandeconomicfactorsmayresultinanEKCorotherqualitativelydierentoutcomes. Weintroducearestrictedclassofvectorvalueddierentialequationsforrepresentingtheevolution ofsocioeconomicandenvironmentalvariableswhichin¯uenceorarein¯uencedbytheprocessof economicdevelopment.Ourmodelincludesnotonlythecompletepathofeachvariableovertime butalsothehighlycriticalinteractionsamongmultiplevariables.Wedemonstrateanalyticallyand numerically that among a multiplicity of possible outcomes, an inverted-U pattern can only be obtainedunderspeci®ccircumstances,andrequiresattentiontothemultiplefactorswhichformthe economic±environmentalsystem,ratherthanasingledominantone. Ó 2001ElsevierScienceLtd. Allrightsreserved. Key words Ð development and environment policy, environmental change, economic growth, environmentalKuznetscurves,systemdynamics 1.INTRODUCTION A concept crystallizing in the development and environment literature is the notion that socioeconomic or environmental measures follow predictable paths associated with growing per-capita income see, for example, Beckerman,1992;Grossman&Krueger,1993, 1995; Holtz-Eakin & Selden, 1992; Kuznets, 1955; Selden & Song, 1994; Sha®k, 1994; Sha®k & Bandyopadhay, 1992). In this grow- ing trend, one speci®c relationship between economic growth and other socioeconomic or environmental variables has become the focus ofincreasingattention.Thisrelationshipisthe ``inverted-U'' curve in which the variable of interestÐinequality or pollution, for in- stanceЮrst increases and then, after a ``turning point,'' declines as income grows. Numerous works have reviewed the as- sumptions and conclusions of the environ- mental Kuznets curves EKCs) literature Arrow et al., 1995; Banuri, 1997; Lopez, 1994;Rock,1996;Stern,Common,&Barbier, World Development Vol.29,No.8,pp.1421±1434,2001 Ó 2001ElsevierScienceLtd.Allrightsreserved PrintedinGreatBritain 0305-750X/01/$-seefrontmatter PII: S0305-750X01)00044-4 www.elsevier.com/locate/worlddev * We are grateful to Gene Grossman, Stephen O'Con- nell,andanonymousreviewersforcommentsonearlier drafts. The ®ndings and conclusions in this paper are thoseoftheauthorsanddonotre¯ecttheviewsofthe WorldHealthOrganization.Finalrevisionaccepted:12 March2001. 1421