Greenhouse gas abatement is a public good, so climate policy is a public‐goods game and suffers from the free‐rider incentives that make the outcome of such games notoriously uncooperative. Adopting an international agreement can change the nature of the game, reducing or exacerbating the uncooperative tendencies of the players. We analyze alternative international agreements as variations of the public‐goods game, and examine the incentives for cooperation under each alternative.