Measuring the effectiveness of international environmental regimes

Although past research has emphasized the importance of international regimes for international governance, systematic assessments of regime effects are missing. This article derives a standardized measurement concept for the effectiveness of international environmental regimes. It is based on a simultaneous evaluation of actual policy against a no-regime counterfactual and a collective optimum. Subsequently, the empirical feasibility of the measurement concept is demonstrated by way of two international treaties regulating transboundary air pollution in Europe. The results demonstrate that the regimes indeed show positive effects-but fall substantially short of the collective optima.