The MIT Technology Review has a very interesting article about ethics and climate change and the knotty problem of discounting future costs:
Typically, economists calculate the discount rate by using money markets to determine the expected return on capital. The reasoning is that the market is the most democratic means of assigning value. But while that practice might work well to account for the value of commodities, Broome argues that calculating the discount rate for action on climate change is far more complex. For one thing, the conventional method doesn’t fully account for the possibility that even if people are richer in the future, climate change might reduce the quality of their lives in other important ways—and thus it underestimates the value of current investments. Broome ends up supporting a rate similar to Stern’s.
But his larger point is, more simply, that even such quantitative economic evaluations need to fully incorporate moral principles.
You can see where this is leading. Market discount rates - the ones that people choose of their own volition - are wrong. The answer is not that the public should be persuaded to adopt a different approach to discounting the future but that a different discount rate must be imposed by unelected "experts".