International Environmental Agreements with Asymmetric Countries

The paper investigates the stability of the International Environmental Agreement in a model of emission reduction. We consider a two stage game, in which in the first stage each country decides whether or not to join the agreement while, in the second stage, the quantity of emissions reduction is chosen. Agents may act cooperatively, building coalitions and acting according to the interest of the coalition, or they make their choices taking care of their individual interest only. Unlike conventional coalition stability models, we assume that countries are not identical but they are divided in two different kinds: developing countries and developed ones; the first have a lower attention about environmental pollution than developed ones. According to environmental awareness, stable coalitions of different sizes occur. On this subject, we present a Maple algorithm to compute the optimal costs and the abatement level for each coalition forms assuming an arbitrary number of developed and developing countries and to determine the internal and the external stability. In order to expand a coalition of any size to the grand coalition, which reaches the greatest abatement level and the lowest aggregate costs, we introduce monetary transfers.