Thanks to Bryan Caplan for his review of my Cartoon Introduction to Climate Change, and double thanks if he cross-posts this response on his blog (although it may mean I have to tweak my jokes about how I’ve been banned by a libertarian blog). [Update: he did!]
As with most academics, Bryan keeps his words of praise to a minimum and instead focuses on criticisms. I will do the same (!) but let’s begin with what appears to be the good news: Bryan says “there is much to like” in the book, that he “genuinely liked” it, and that he was “entertained and enlightened”.
On second thought, however, this “good news” is remarkably vague, and I am worried that it is intentionally so. It is this worry—and not narcissism—that leads me to ask: What exactly did Bryan like in the book? What was he enlightened about? And is he hiding something that he doesn’t want to tell his readers, or perhaps even something that he doesn’t want to admit to himself?
I ask this because Bryan exhibits all of the symptoms of a global-warming-related malady known as Selective Scientific Ignorance. I did a Google search for statements that Bryan has made about climate science, and the most encouraging things I was able to come up with were (1) a post from 2007 about how he believes in “moderate global warming” because global warming skeptics aren’t taking bets and (2) a reference to a 2007 survey of climate scientists. (BTW, here’s the 2013 survey update.) But I also found his review of Superfreakonomics, a review that calls out as a highlight the book’s “surprisingly skeptical look at global warming”. (For a less flattering view, see my back-and-forth with Steve Levitt and/or this classic post that ends with climatologist Raymond Pierrehumbert, Levitt’s colleague at the University of Chicago, giving Levitt the Google Map directions to his office.) And I found his review of my Cartoon Macro book, in which he somehow manages to focus on the wonders of his hero, Julian Simon—“For whom my son Simon Caplan is named“—while ignoring Simon’s failed guess that “global warming is likely to be simply another transient concern, barely worthy of consideration ten years from now.” (Simon wrote that in 1996).
Why do I call this Selective Scientific Ignorance? Because it doesn’t stop Bryan from pontificating about other matters, like geoengineering, about which he writes elsewhere that “all things considered, geoengineering looks far superior to other policy options on the table.” More on this below, but, gosh, is this person who has considered all things really the same person who says that his “understanding of natural science is very weak“? More on geoengineering below, but I for one am eager to hear what Bryan has to say about ocean acidification, or about the impact of massive atmospheric sulfur injections on global weather patterns.
Like Bryan, I’m not a natural scientist, and I’m not an epidemiologist either. But I’m comfortable saying things like “smoking causes cancer” instead of dog-whistle baloney statements like “some scientists say that smoking causes cancer” or “nobody is making bets that smoking doesn’t cause cancer” or (holy cow, Bryan!) “Key question: Does smoking really dominate if you regress lung cancer deaths over the past century with cigarette consumption and also placebo variables like church attendance per capita, the Dow Jones, televisions per capita, etc.?” (More on this from Bryan here; don’t miss his “I wish experts would tell me” plea at the end that makes me wonder if he needs Google Maps too.)
I could go on, but I’ll just call the question. Bryan, you said that you were “enlightened” by the book, so what exactly did you learn from it? More importantly, what are you willing to publicly acknowledge about climate science? Are you comfortable saying that carbon dioxide is a greenhouse gas? That human emissions of carbon dioxide are raising atmospheric CO2 concentrations? That global temperatures have been increasing over the past century? That humans are partly responsible for those increasing global temperatures? That “it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century”?
The Cartoon Introduction to Climate Change provides my answers to these questions (Yes, Yes, Yes, Yes, and No I’m Not Comfortable Saying This But I Am Comfortable Saying That The Vast Majority Of Scientists Are Convinced), so I’d like to hear what you have to say about them, Bryan. Can you provide answers? Or are you just going to continue to tolerate in yourself a lazy acquiescence that saves you the trouble of confronting your own views, of confronting politicians like Marco “our climate is always changing” Rubio, and of confronting fellow economists like Steve Levitt who write misleading baloney about how “When Al Gore urges the citizenry to sacrifice… the agnostics grumble that human activity accounts for just 2 percent of global carbon-dioxide emissions”? (Now that you’ve read my book you know why that’s misleading baloney, right?)
Okay, now that that’s out of the way, let’s proceed to the numbered points of attack in Bryan’s original review. (And I hope that everyone will keep in mind that Bryan “genuinely liked” the book!)
1) “We can use cost-benefit analysis [CBA] to put climate change in perspective.” It’s much harder than you think, Bryan. For example, read Pindyck 2013, who argues that risks from climate change should be thought about as similar to the Cold War risks of thermonuclear conflict between the US and the Soviets. (Would you advocate the use of CBA to “put the Cuban Missile Crisis in perspective”?)
Moreover, there are four independent reasons that the waters for CBA are muddy. Reason #1 is that CBA has trouble dealing with uncertainty: if there’s a (say) 1% chance that climate change will be catastrophic and a 99% chance that it will be no big deal, how do you account for that in CBA? I don’t think anybody who knows the St Petersburg Paradox (and Marty Weitzman’s related work on “fat tails”) has a good answer here. Reason #2 is that CBA has trouble dealing with inter-generational issues involving the distant future. (More on this below.) Reason #3 is that CBA has trouble dealing with intra-generational issues, e.g., the likelihood that climate change will be harder for Bagladeshis than for Americans. (And no, I’m not buying into any “hypothetical compensation schemes”.) Reason #4 is that CBA has trouble dealing with non-market valuation on the massive scale that we’re talking about here; a good rule of thumb is that CBA is good for engineering but less good for geoengineering.
Put those four reasons together and it’s clear to me that you’re opening a can of worms for no good reason. That’s fine in a textbook—it’s often the point of textbooks!—but in a cartoon book there’s no space.
2) “Cost-benefit analysis is sensitive to discount rates.” See above, but more importantly I think you’re being too technical and (like most discount-rate fetishists of all political persuasions) missing the real questions. The real questions are about the wealth of future generations relative to the current generation, and about their preferences. Unfortunately it’s pretty hard to answer these questions—especially, as we note in the book, about the distant future—so when you ask the hypothetical Kaldor-Hicks question that underlies discount rates (How much money would we have to set aside now to compensate future generations for climate damages?) you end up in the can of worms again.
3) “Insurance is NOT a no-brainer.” You’re absolutely right that buying an extended warranty for a toaster is a bad idea, but the cartoon book repeatedly emphasizes low probability outcomes that are catastrophic, which is a pretty good focal point for insurance. Of course, as you point out, the attractiveness of insurance also depends on the cost. I agree with you that the cartoon book lacks some subtlety on this point, and if I’d had twice as many pages I would have done better. Instead we get what I think is a reasonable summary given the space available: “If we give up a small piece of cake… we can get peace of mind.”
4) “Leading techno-fixes really do look vastly cheaper than abatement.” Ah yes, here we are, back to Mr. All Things Considered. Unfortunately, I don’t really have any more fireworks to set off because I am no expert on geoengineering. I certainly have nothing against considering it. But I also know (and you should too) that the “costs” of pumping SO2 into the upper atmosphere are not limited to the dollar costs of pumping the stuff up there. So I’m concerned that geoengineering is being oversold by people like you who haven’t thought it all the way through and have a “What, me worry?” approach to the risks of climate change. PS. At the very least we should all be able to agree that Levitt and Dubner were way off in claiming (in Superfreakonomics) that “perhaps the single best objection” to their garden hose idea was that “it’s too simple and too cheap.” Way off. Yes?
5) “National emissions regulations can have perverse global effects.” Here I think you’re making a mountain out of a molehill. True, national efforts to reduce (say) oil consumption would shift the global demand curve to the left, which would lead to a new equilibrium and (provided the supply curve is not perfectly elastic) a smaller drop in consumption than a naive analysis would suggest. But… why is this perverse? (It just sounds like economics to me!) What is perverse in my view is that you fail to note that the book emphasizes the importance of international action, e.g., with the division of the world population into “5 Chinas”.
6) “Expressive voting is a big deal.” I know this is one of your hobby-horses, Bryan, but I’m afraid you haven’t convinced me that this is a big deal. Look at the climate legislation that’s out there: the British Columbia carbon tax, the (failed to clear the Senate) Waxman-Markey bill, California’s AB 32 cap-and-trade system, etc. It all looks pretty substantive to me. Do we really need to get into the psychology of voting, whether from greens who obsess about recycling or from free-market folks who obsess about the hockey-stick illusion? The answer—or at least my answer, especially in a cartoon book that is supposed to cover the basics of climate change in 200 short pages—is No.