气候政策存在差异时的碳边境调节、气候俱乐部与补贴竞赛

Jurisdictions adopt climate policies that vary in terms of both ambition and policy approach, with some pricing carbon and others subsidizing clean production. We distinguish two types of policy spillovers from these diverse approaches. First, when countries have different levels of climate ambition, free-riders benefit at the expense of more committed countries. Second, when countries pursue different approaches, carbon-intensive producers within cost-imposing jurisdictions are at a relative competitive disadvantage compared with producers in subsidizing jurisdictions. Carbon border adjustments and climate clubs respond to these spillovers, but when countries have divergent approaches, one policy alone cannot address both spillovers. We also consider the policy dynamics arising from carbon border adjustments and climate clubs; both have the potential to encourage upward harmonization of climate policy, but come with risks. Further, the pressures of international competition may result in subsidy races, with attendant risks and benefits.