Here’s my point-by-point reply to Daniel Reeves.  He’s in blockquotes; I’m not.

Daniel gets the last word if he wants it!

Bryan seems to start by acknowledging that 6 degrees of warming (we’re approaching 1 degree so far, for those just tuning in) would be devastating and that a 10% chance of that by the end of the century warrants mitigation efforts. He even acknowledges that — warming being proportional to cumulative historical emissions — we can’t afford to wait.

Not really.  My actual view is that I’m not qualified to judge these questions, and reading Climate Shock didn’t make me feel noticeably more able to judge.  As I explained at the outset of the bet, I would have to study this subject for years to directly judge the evidence.

The whole point is to assess whether the alarmism is correct. If you dismiss the authors for the very fact that they think alarmism is correct then you are fundamentally closed-minded on this issue and probably shouldn’t have accepted the bet. (To be clear, I’ve paid up already.)

Indeed you have, Daniel.  But in my own defense, I did warn you upfront that you were over-estimating my open-mindedness.  Given the complexity of the evidence, all a layman can honestly do is assess credibility.  Wagner and Weitzman didn’t wow me on that count.

This sounds like assuming bad faith. My sense from the book was that the authors were incredibly conscientious and intellectually honest. But maybe I’m misunderstanding you and you’re agreeing that it’s impressive that the authors resisted the temptation to exaggerate the probability?

My point is just that their claim was more modest than I expected.  This has two effects: (a) it slightly raises their credibility, but (b) made me slightly less worried about climate change.

(Also some of the bias is trying to counteract the other side’s bias, which is what turns the whole topic into an epistemic nightmare. I don’t think you can just pin all the bias on the left. Isn’t there even greater right-wing bias to rationalize business-as-usual?)

Both sides are intellectually dishonest.  Which is worse on this particular issue?  The right is probably worse on the details of the science, but the left is probably worse on the policy analysis.  Though again, I would have to study the issue for years to do more than guess.

Some policy interventions — say, funding carbon capture — don’t have that possible failure mode. [of greatly slowing economic growth in LDCs]

Side note: I think Pigouvian taxes should be philosophically fundamental to laissez faire capitalism (by maximizing how much faire we can laissez) and that we want a carbon tax even if — in light of geoengineering? — it’s lower than Wagner and Weitzman recommend. I also disagree that Pigouvian taxes are fundamentally impoverishing. I’m a fan of revenue-neutral carbon taxes.

Wagner and Weitzman didn’t seem very optimistic about carbon capture as a primary policy solution.  See here and here for my views on Pigovian taxation.  You are correct that Pigovian taxes generally have a lower deadweight cost than regular taxation.  Indeed, they can have a negative deadweight cost.  Even so, high carbon taxes would plausibly sharply slow poverty reduction in the Third World.

Wait, can I still win this bet on a technicality if Wagner and Weitzman inadvertently convinced you that we should pursue stratospheric aerosol injection (what they mostly mean by geoengineering in the book)? I don’t know how serious I am with that question but I’d love to understand your thinking more!

No, because I’ve long been sympathetic to geoengineering, and the bet requires me to do a 180.

I may be more trusting than you but I’d only have distrusted them on those grounds if they’d argued against nuclear energy. Wagner and Weitzman think policy intervention should be limited to carbon taxes. Nuclear energy doesn’t emit carbon so they are implicitly pro-nuclear. I’m sure they’d agree about the absurd regulatory burden as well.

If they had wanted to signal their lack of left-wing bias, they would have gone out of their way to praise nuclear power.  So why didn’t they?

Update: David Henderson is disturbed by my claim that, “Both sides are intellectually dishonest.”  If the issue is too complicated to decide without years of study, how can I so casually dismiss almost everyone as “dishonest”?  My reply: I’m talking about the vast majority of people who hold strong opinions despite (a) the complexity of the issue, and (b) the minimal time they have actually spent studying the science.  You don’t have to understand the evidence to know when other people are forming their beliefs negligently.