Collective risk social dilemma and the consequences of the US withdrawal from international climate negotiations

International climate negotiations represent an interesting theoretical problem, which can be analyzed as a collective risk social dilemma as well as an n-person bargaining model. The problem is made more complicated by politics due to the differences between: (1) total and per capita emissions; and (2) present-day and cumulative emissions. Here, we use a game theoretic approach in conjunction with the literature on effort-sharing approaches to study a model of climate negotiations based on empirical emissions data. We introduce a ‘fair equilibrium’ bargaining solution and examine the consequences of the United States’ withdrawal from the Paris Agreement. Our results suggest that the collective goal can still be reached but that this requires additional greenhouse gas emissions cuts from other countries, notably, China and India. Given the history of climate negotiations, it is unclear if these countries will have sufficient political will to accept the additional costs created by the US defection.