The Tragedy of the Commons in the Presence of Regime Shift Risk[La tragédie des biens communs face au risque de changement de régime]

Climate change poses substantial threats capable of triggering a drop in the renewability and quality of natural resources. In this paper, we extend standard stock-recruitment models to examine how the risk of this environmental event affects the tragedy of the commons associated with decentralized harvest decisions made by players exploiting a common pool renewable resource. We use general functional forms and allow for endogenous or exogenous hazard rates. Our analysis indicates that anticipating this environmental event critically affects harvest incentives. For instance, linear strategies may not hold in equilibrium when the hazard is stock dependent. The representative player can increase extraction today in response to a higher risk of decreased both resource renewability and quality. We find conditions under which environmental risk, in addition to inducing conservation, mitigates the tragedy of the commons. Calibrating our model to the Baltic Cod fishery, we find that players' strategic responses to the estimated endogenous regime shift risk may reverse the tragedy of the commons.