Collective management often requires formal commitments as well as mechanisms for enforcing compliance. Current efforts to slow global warming have focused on commitments and given scant attention to enforcement. They have followed the "standard model" when creating international environmental treaties: set commitments first, defer procedures for enforcement until later, and rely on "soft" (or nonexistent) measures for enforcing compliance. However, the evidence that supports use of the "standard model" is misleading and does not apply to global warming. In most international environmental agreements, it has been possible to defer or ignore enforcement procedures because nearly all commitments have been modest and enforcement has not been necessary. What little wisdom exists on the design of enforcement procedures is based heavily on the experience in the Montreal Protocol on Substances that Deplete the Ozone Layer. But a close look at that experience shows that deferring the creation of enforcement procedures--in particular, the Protocol's "Non-Compliance Procedure"--until after most commitments were in place severely weakened the procedures, because countries that feared strong enforcement would consent only to a soft mechanism. The few countries that have brazenly violated the agreement (e.g., Russia) are changing their behavior only in response to incentives--especially large compensation programs and threats of trade sanctions--that are actually external to the Protocol's enforcement system. By itself the Protocol's hobbled enforcement process has been able to handle only relatively minor violations for which its small carrots and sticks are adequate.
The design of an effective global warming regime must focus on enforcement mechanisms as well as commitments. Failure to do so will only perpetuate the shallowness of international environmental law--commitments that appear bold but have little direct impact on a country's behavior except where changes in behavior are in the country's self-interest. This article reviews the record of compliance with and enforcement of international environmental agreements. It also examines the prospects for enforcement under major alternative types of commitments that might be included in a global warming regime. A system of tradable permits is most vulnerable to unraveling if cheating is rampant, but a trading system in which permit-holders are liable for noncompliance ("buyer liability") is the easiest to enforce because the market would impose enforcement with price signals. Flaky permit sellers would command a lower price than trustworthy vendors. However, the concept of emission trading, which is included in the 1997 Kyoto Protocol on global warming, will be stillborn because it requires the impossible task of distributing permits worth trillions of dollars. That leaves other alternatives, such as coordination of carbon taxes or other national policies, which are not easily enforced.
Policymakers are thus in a quandary. If they focus on setting prices or quantities of emissions, they must overcome a huge hurdle--enforcement--for which prior experience with international environmental law (e.g., the Montreal Protocol) is an imperfect guide and conventional wisdom is worse than no guide at all. Mechanisms much more powerful than those offered by the "standard model" will be needed. Policymakers could focus commitments on "liberal states" in which...