Optimal climate policy under the possibility of a catastrophe

This paper concerns optimal emissions of greenhouse gases when catastrophic consequences are possible. A numerical model is presented, which takes into account both continuous climate-feedback damages as well as the possibility of a catastrophic outcome. The possibility of a climate catastrophe is a major argument for greenhouse gas abatement even in absence of continuous damage. Special attention is given to the subjective probability of a catastrophe and the pure rate of time preferences, and implicit values of these parameters are calculated if an emissions stabilisation target is assumed optimal. Finally, the expected value of perfect information about the probability of a catastrophe is estimated.