Buy Coal! A Case for Supply-Side Environmental Policy
研究发现，气候联盟通过购买外国化石燃料矿藏并保护它们，可以解决搭便车问题，实现最优环境政策，比传统减排政策更有效。
Free-riding is at the core of environmental problems. If a climate coalition reduces its emissions, world prices change and nonparticipants typically emit more; they may also extract the dirtiest type of fossil fuel and invest too little in green technology. The coalition's second-best policy distorts trade and is not time consistent. However, suppose that the countries can trade the rights to exploit fossil-fuel deposits: As soon as the market clears, the above-mentioned problems vanish and the first-best is implemented. In short, the coalition's best policy is to simply buy foreign deposits and conserve them.