Ian W.H. Parry, Mr. Simon Black, and Karlygash Zhunussova
Carbon pricing should be a central element of climate mitigation strategies, helping countries transition to ‘net zero’ greenhouse gas emissions over the next three decades. Policymakers considering introducing or scaling up carbon pricing face technical choices between carbon taxes and emissions trading systems (ETSs) and in their design. This includes administration, price levels, relation to other mitigation instruments, use of revenues to address efficiency and distributional objectives, supporting measures to address competitiveness concerns, extension to broader emissions sources, and coordination at the global level. Political economy considerations also affect the choice and design of instruments. This paper discusses such issues in the choice between and design of carbon taxes and ETSs, providing guidance, broader considerations, and quantitative analyses. Overall, carbon taxes have significant practical advantages over ETSs (especially for developing countries) due to ease of administration, price certainty to promote investment, the potential to raise significant revenues, and coverage of broader emissions sources—but ETSs can have significant political economy advantages.
Countries are increasingly committing to midcentury ‘net-zero’ emissions targets under the Paris Agreement, but limiting global warming to 1.5 to 2°C requires cutting emissions by a quarter to a half in this decade. Making sufficient progress to stabilizing the climate therefore requires ratcheting up near-term mitigation action but doing so among 195 parties simultaneously is proving challenging. Reinforcing the Paris Agreement with an international carbon price floor (ICPF) could jump-start emissions reductions through substantive policy action, while circumventing emerging pressure for border carbon adjustments. The ICPF has two elements: (1) a small number of key large-emitting countries, and (2) the minimum carbon price each commits to implement. The arrangement can be pragmatically designed to accommodate equity considerations and emissions-equivalent alternatives to carbon pricing. The paper discusses the rationale for an ICPF, considers design issues, compares it with alternative global regimes, and quantifies its impacts.