Anticipating moral hazard undermines climate mitigation in an experimental geoengineering game

Geoengineering is sometimes touted as a partial solution to climate change but will only be successful in conjunction with other mitigation strategies. This creates a potential for a “moral hazard”: If people think geoengineering alone will mitigate climate change, they may become overly optimistic and reduce support for other necessary mitigation efforts. We test this in a series of economic games where players in groups must prevent a simulated climate disaster. One player, the “policymaker,” decides whether to implement geoengineering. The rest are “citizens” who decide how much to contribute to incremental mitigation efforts. We find that citizens contribute to mitigation even when the policymaker uses geoengineering. Despite this, policymakers expect that citizens will engage in moral hazard. As a consequence, policymakers do not use geoengineering even though everyone would be better off if they did so. Anticipating moral hazard undermines mitigation even though moral hazard itself does not.