The document discusses designing carbon pricing instruments to support ambitious climate policy. It notes that while carbon pricing is efficient and raises revenue, political constraints have limited its implementation. These constraints include concerns about competitiveness, household energy bills, dependence on fossil fuels, and policy misalignments. The document outlines strategies to overcome these barriers, including international price convergence, targeting exemptions, and realigning incentives. It also discusses levels of international cooperation on carbon pricing, from agreeing on principles to fully linking emissions trading systems. The discussion raises questions about how to help overcome political constraints and facilitate coordination on carbon pricing policies.