I'm very pleased to have had a comment by the eminent economist Richard Tol (even it is was to tell me that I was wrong about the Stern Report - the report was still flawed, but not for the reasons I had put forward).
Here's what he says:
Stern managed to focus the discussion about the Stern Review on the discount rate used. The issue is not that Stern argues for a particular discount rate. That is his right as a a citizen of a democratic country. The issue is that he used a single discount rate (without performing a sensitivity analysis) and that he used a discount rate that differs from the discount rate typically used by his own, democratically-elected government. And all without alerting the reader. Stern's use of the discount rate is a clear case of manipulation.
The sloppiness of the Stern Review is perhaps best illustrated with its assessment of an optimal climate policy. (By the way, the Stern Review concludes that the previously formulated long-term target of the UK government is exactly right.) Stern's "optimum" does not meet the first-order conditions. In the optimum, marginal costs should equal marginal benefits. Stern recommends that greenhouse gas concentrations be stabilized at 550 ppm CO2eq, but at that point his (faulty) estimates of marginal costs do not equal his (faulty) estimates of the marginal benefits.
When I pressed him over this, the paraphrased reply was that Newton and Leibnitz are so passe.
The subsequent discussion is very interesting too. In essence Stern is arguing that a philosopher king should tell us what is right, while Tol is making the libertarian case - that ordinary people should choose their own way. Global warming enthusiasts should be clear, both to themselves and to the public they seek to persuade, that this is their intention.
Which brings me back to my original point: Stern should be strongly criticised for not making this clear to his readers, and Ed Stourton, one of the most senior journalists at the BBC should hang his head in shame for precisely the same reason.