In 1997, in Kyoto, Japan, the Dutch government joined 130 other nations in signing a treaty called the Kyoto Protocol, committing the nations to reducing their emissions of methane and other global-warming gases. Under the terms of this agreement, the Dutch government gets equal credit for battling pollution anywhere on the planet. In Dutch urban areas, overall air quality is better than in many Brazilian cities. Other things being equal, the marginal cost of further pollution abatement in urban areas is higher in the Netherlands than in Brazil. For example, the cost of eliminating a ton of methane from a city’s atmosphere is $40 to $50 in the Netherlands but only $4 to $5 in Brazil. This large differential has given the Dutch government an incentive to meet much of its Kyoto promise to reduce pollution by cleaning up methane emissions in Brazil. In this way, it spends less than it would have had to spend to clean up an equal amount of pollution at home.

What does the Kyoto Protocol assume about the marginal benefit of reducing pollution in various countries around the world?