There have been significant improvements over the past four decades in our ability to estimate the economic value of environmental amenities and disamenities. The development of many new techniques has broadened what can be measured to include climate change impacts, damages from hazardous waste...

I examine the risk/return tradeoff for environmental investments, and its implications for policy choice. Consider a policy to reduce carbon emissions. To what extent does the value of such a policy depend on the expected future damages from global warming versus uncertainty over those damages,...