International environment conventions: The case of uniform reductions of emissions

Several serious environmental problems have a global character. International cooperation to reduce emissions for this type of problems often takes the form of an agreement among the cooperating countries to cut back emissions by a uniform percent rate compared with some base year. This type of agreements has two disadvantages. In the first place, it is well known from environmental economics that equal percentage reductions of emissions from different sources usually gives an inefficient outcome, in the sense that the same environmental goals could be achieved at lower costs through a different distribution of emission reductions. A second problem with agreements of equal percentage reductions is that not all countries will find it in their interest to participate in such agreements. In the paper, it is assumed that the set of countries which participate in an agreement is endogenously determined, with a country participating in an agreement provided that this makes the country better off than it would have been in a situation without any agreement. The agreement among the participating countries is assumed to be a uniform percentage reduction of their emissions. The countries have different opinions about what this uniform percentage should be. In the paper, it is assumed that the outcome is determined by the median country of the participating countries. The assumptions above lead to a particular equilibrium, in which some but not all countries cooperate. The equilibrium reduction of emissions for the cooperating countries is also derived. This equilibrium compared with the first best optimum within the context of simple numerical example.