Domestic politics and climate change: international public goods in two-level games

We use the theory of two-level games to explore how domestic constraints affect the outcome of bargaining games over national contributions to an international public good such as global climate change, and to discuss the implications for the Schelling conjecture. We model the international negotiations on two dimensions-domestic and foreign contributions to the international public good-and extend the basic two-level model by examining a nonzero sum, two-dimensional conflict model on level one that includes characteristics of both conflict and cooperation. Our main results suggest that if the domestic game is a ratification game (as in the presidential system of the US), then contributions do not exceed those in a benchmark game without domestic constraints. But if the domestic game is an election game (which is more important in the parliamentary system of most continental-European countries), contributions can actually be higher than the benchmark.