Climate Negotiations in the Lab: A Threshold Public Goods Game with Heterogeneous Contributions Costs and Non-binding Voting

We model the climate negotiations and the countries’ individual commitments to carbon dioxide reductions as a threshold public goods game with uncertain threshold value. We find that a non-binding unanimous voting procedure on contribution vectors leads to frequent agreement on an optimal total contribution and high rates of compliance, even in the case of heterogeneous marginal contribution costs. However, groups that do not reach agreement perform worse than the baseline treatments without a voting procedure. The contribution vectors chosen by the groups point to a predominant burden-sharing rule that equalizes individual contribution costs, even at the cost of the group’s total payoff.