New roads to international environmental agreements: the case of global warming

We relax the single agreement and open membership assumptions that are implicit in the concept of internal and external stability, which has been widely used to analyze the formation of international environmental agreements (IEAs). By means of numerical simulations we investigate the impact of these changes using a dataset derived from an integrated assessment model of climate change. Our simulations show that multiple agreements are superior to a single agreement and exclusive membership is superior to open membership in ecological and welfare terms. Moreover, we demonstrate the importance of transfers for successful treaty making and we derive recommendations for the design of future IEAs.