Production often causes pollution as a by-product. Once environmental degradation becomes too severe, regulation is introduced by which society forces the economy to make a transition to cleaner production processes. We model this transition as a change in "general purpose technology" and...

We derive the optimal contributions to global climate policy when countries differ with respect to income level and pollution intensity. Countries' growth rates are determined endogenously, and abatement efficiency is improved by technical progress. We show that country heterogeneity has a...