Studies in both corporate fi nance and environmental economics have described how discount rates should vary with the maturity of a project. The former suggests that the cost of capital should increase with the time horizon of the cash flow, while the latter recommends declining term structures...

Climate change is real and dangerous. Exactly how bad it will get, however, is uncertain. Uncertainty is particularly relevant for estimates of one of the key parameters: equilibrium climate sensitivity—how eventual temperatures will react as atmospheric carbon dioxide concentrations double....

As the most important driver of long-term project evaluation, from climate change policy to infrastructure investments, the social discount rate (SDR) has been subject to heated debate among economists. To uncover the extent and sources of disagreement, we report the results of a survey of over...