Why would countries invest resources to protect the global atmosphere, a global common-pool resource? After all, this is an open-access resource with no restrictions on appropriating its benefits. Furthermore, why would they do so under the aegis of a weak global regime (the United Nations Framework Convention on Climate Change, UNFCCC) that has virtually no provisions for sanctioning noncompliance and when the largest contributor to the problem is not participating in the regime? This article examines why a number of countries have implemented the UNFCCC. I hypothesize that countries implement UNFCCC because they corner domestic environmental benefits, namely reduction in local pollution. In my empirical analysis of 127 countries, employing an ordinal logistic regression model, I find that local air pollution is associated with higher levels of implementation of the UNFCCC. Thus, I conclude that the incentives to implement a relatively weak global regime can be found in the domestic political economy.