Jerry, I think we’ve gotten to the nub of it. You say:
Jim, I do not agree with you that uncertainty regarding future arming strengthens the case for cap-and-trade or other mitigation programs. As the Goklany paper I linked to earlier demonstrates, even if the worse comes to pass, we’re still better off with a policy of adaption rather than mitigation. [Bold added]
But the root question here is: What is the worst that could come to pass? Goklany’s analysis, which I have elsewhere endorsed, is in my view quite correct if we accept the IPCC’s distribution of potential climate impact. That is, if the worst warming considered possible in the probability distribution of possible impacts published by the IPCC really is the “worst that could come to pass.” But what if they’re wrong about how bad the “worst” could possibly be, and it could be even worse than their worst case? This is the only (honest) argument left open to cap-and-trade advocates if you simply accept the findings of the IPCC. It actually is not a crazy worry, in my view, but it’s a pretty thin reed to use to support a massive restructuring of the energy sector of the world’s economy.
Said differently, if you accept every word in the currently operative IPCC assessment report, advocates of cap-and-trade have to argue not that “science says X will happen” (that is, that the expected case projects X), and not even that “science says X has some low odds of happening,” but actually have to argue that “it’s possible that the IPCC is wrong, and things could be even worse than their worst case,” in order to make a rational argument for cap-and-trade. As you say (and as I’ve said many times), when considered carefully, this is nothing more than the somewhat grandiosely-named Precautionary Principle. Don’t you think you can win that argument?
You then say:
You may be right that we would be better advised to accept the IPCC’s narratives about the science and likely future harms but to resist aggressive mitigation by marshalling economic arguments. Unfortunately, many people who accept the lurid scientific narratives in the press about future warming are not in any mood to have a conversation about costs and benefits.
Yes, but the IPCC doesn’t traffic in lurid narratives. If you look carefully at what the formal reports say, they are quite circumscribed. In my experience, it is much, much more powerful to counter these ridiculous claims of the oceans swallowing New York and the entire American heartland becoming a dustbowl or whatever by simply citing the relevant portions of these authoritative documents, than by trying to invent some alternative scientific counter-establishment.