This post is by Jon A. Anda, President of the Environmental Markets Network at Environmental Defense. A version of this post was published in the Financial Times on December 4, 2007.
A November 28 column by John Kay in the Financial Times, "Climate Change: the (Groucho) Marxist approach", starts with a quote from Groucho Marx: "Why should I do anything for posterity? What has posterity ever done for me?" Groucho’s position may be morally indefensible, Kay says, but "[t]he problem of weighting the present and the future equally is that there is a lot of future." From an economic standpoint, valuing future people equally would require unrealistically great sacrifices by those living today.
There’s a problem with this argument. It’s based on a rather totalitarian belief in net present value (NPV) as the means to evaluate policy – a simple calculation of the benefits of action (the cost of doing nothing) minus the costs of action. If a 5 percent discount rate applied to base-case cost and damage estimates yields a negative NPV for policy, does that mean we reject it?