Climate policy poses a dilemma for environmental economists. The economic argument for stringent GHG abatement is far from clear. There is disagreement among both climate scientists and economists over the likelihood of alternative climate outcomes, over the nature and extent of the uncertainty...

Major carbon-pricing systems in Europe and North America involve multiple jurisdictions (countries or states). Individual jurisdictions often pursue additional initiatives—such as unilateral carbon price floors, legislation to phase out coal, aviation taxes or support programs for renewable...

This paper considers the question of under what circumstances a new environmental regulation should "phase in" gradually over time, rather than being immediately implemented at full force. The paper focuses particularly on climate policy, though its insights are more general. It shows that while...