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...

We present an integrated framework to understand the emissions impact of unilateral overlapping policies within a carbon-pricing system. "Internal carbon leakage" captures emissions displacement within the system (e.g., due to greater product imports from a neighbouring country). The waterbed...