This paper explores two different conceptions of how an emerging climate regime might evolve to strengthen incentives for more vigorous cooperation in mitigating global climate change. One is the paradigm that has figured most prominently in negotiations to this point: the establishment of targets and timetables for countries to limit their aggregate greenhouse gas emissions. The other approach consists of a variety of loosely coordinated smaller scale agreements, each one of which addresses a different aspect of the challenge, and is enforced in its own way. Our primary conclusion is that an agreement of the first type may be more cost-effective, but that a system of agreements of the second type would likely sustain more abatement overall.
Negotiation of targets and timetables may have advantages for cost-effectiveness, but poses great difficulties for enforcement.
Climate change mitigation is a colossal collective action problem.
Climate treaties should yield a positive net benefit for every country and for the world; sustain broad participation; and impose obligations that are permanent and that can be enforced using credible mechanisms.
A combined approach is possible, with targets and timetables being expressed as goals and with specific agreements being negotiated to meet those goals.
Smaller scale agreements that control individual gases or the emissions of individual sectors separately create more options for enforcement.