A fully global system of targets and trading might appear to be the ideal policy but is politically unrealistic. Developing countries, which cannot as confidently project their future emissions and bitterly oppose any perceived constraint on their growth, are not about to take on quantified emission limits. A more realistic alternative would be policy-based commitments: countries agree to undertake policies that reduce emissions, while also advancing core development objectives such as economic growth or enhanced energy security. China, for instance, could commit to strengthening its existing energy efficiency and renewable energy goals, while Brazil and other rainforest countries could commit to reducing deforestation. Though developing countries would have no binding emission limits, they could participate in trading through a system awarding them emission credits for meeting or exceeding their policy commitments, thus providing a powerful market incentive for robust compliance.

A flexible new framework could include other types of commitments. One promising approach is sectoral agreements: governments commit to targets, standards, or other measures to reduce emissions from a given sector such as transportation or electricity, rather than across the economy. Particularly in industries producing globally traded goods, this would help overcome competitiveness issues by ensuring for a more level playing field. Governments could also commit to joint technology efforts, both to develop long-term breakthrough technologies and to ensure that developing countries have access to them.

Finally, a post-2012 agreement must help poor countries cope with increased flooding, drought, and other inevitable consequences of global warming. It is a cruel irony that these impacts will fall disproportionately on sub-Saharan Africa and other regions that are least responsible for climate change and least able to adapt. Stronger international support for adaptation is not only a moral imperative, but a political necessity.

A new treaty that allows countries different but limited pathways could both build on the Kyoto Protocol and move past it. The natural venue for negotiating such a pact is the 1992 UN Framework Convention on Climate Change, Kyoto’s parent agreement, which has been ratified by virtually every nation––including the United States. The precise form of this new treaty can emerge only through negotiation, as it must be tailored to the specific circumstances of very diverse countries. But the basic elements are clear. They include binding targets for developed countries to curb their emissions and drive the global emissions market, binding policy commitments for developing countries, possibly with sectoral and technology agreements overlaid, and stronger support for adaptation.

As the US climate debate advances, the question of international engagement will inevitably rise to the forefront.Already, the Senate Foreign Relations Committee has passed a resolution calling for the United States to negotiate under the Framework Convention to establish commitments for all major-emitting countries. To some, the goal may appear distant, if not wholly fanciful. But if and when the United States is prepared to lead, others, too, will be far better able to muster the necessary political will. Therein lies our only real hope for a new global compact to confront global warming.