A constant social discount rate cannot reflect both a reasonable opportunity cost of public funds and an ethically defensible concern for generations in the distant future. We use a model of hyperbolic discounting that achieves both goals. We imbed this discounting model in a simple climate...

Low probability catastrophic climate change can have a signifcant influence on policy under hyperbolic discounting. We compare the set of Markov Perfect Equilibria (MPE) to the optimal policy under time-consistent commitment. For some initial levels of risk there are multiple MPE; these may...