I review the complex welfare economic issues that arise in environmental decision-making over very long periods, as in cases relating to climate change and biodiversity loss. I also consider the issues that arise in choosing a discount rate to apply to very long-run projects and indicate how...

In a series of papers, Martin Weitzman has proposed a Dismal Theorem. The general idea is that, under limited conditions concerning the structure of uncertainty and preferences, society has an indefinitely large expected loss from high-consequence, low-probability events. Under such conditions,...

Weitzman's Dismal Theorem has that the expected net present value of a stock problem with a stochastic growth rate with unknown variance is unbounded. Cost-benefit analysis can therefore not be applied to greenhouse gas emission control. We use the Generalized Central Limit Theorem to show that...