Climate Leadership by Conditional Commitments

Under the 2015 Paris climate agreement, each Party sets its own mitigation target by submitting a Nationally Determined Contribution (NDC) every five years. An important question is whether including conditional components in NDCs might enhance the agreement s effectiveness. We report the results of a closely controlled laboratory experiment based on a mixed sequential-simultaneous public good game with one leader and three followers that helps answer this question. The experiment investigates how two factors infl uence the effectiveness of leadership based on intrinsically conditional commitments. Measuring e¤ectiveness in terms of followers ' and total contributions, we find that it may help if the conditional promise is credible and if its implementation in fluences followers' welfare substantially. Importantly, however, for both factors we fi nd a signi cant effect only if the leader does not reap disproportionate gains from the group' s efforts. These fi ndings have important implications concerning the future success of the Paris agreement. This is a pre-copyedited, author-produced version of an article accepted for publication in Oxford Economic Papers following peer review. The version of record is available online at: http://dx.doi.org/10.1093/oep/gpx045