We’ve all spent more than enough time on this, but since my previous posts are getting some play (e.g., from Greg Mankiw) I’m going to take the time to write up a few more (concluding?) thoughts:
First: In an earlier post I wrote that “since Steven Levitt doesn’t do any research on climate economics my hunch is that Dubner is responsible for the misleading perspective in the book.” But my emails with Levitt do not support my hunch, so I’m backing away from it and throwing my hands up about who’s responsible. My apologies (I guess? 🙂 to one or both of Levitt and Dubner for putting this hunch out there.
Second: I stand by what I wrote to Levitt earlier, which is this: “My perspective is that you are probably correct that there are few factual errors in the book (I’ll wait for the footnotes and let you know if I find any errors 🙂 but that you are ignoring the overall thrust of the chapter, which is terribly misleading.”
Third: The best way I have of summarizing my conclusion about the “terribly misleading” thrust of the chapter—beyond my previous statement that, e.g., it’s misleading to divide the world into “true believers [who] bemoan the desecration of our earthly Eden” and “heretics [who] point out that this Eden… once became so naturally thick with methane smog that it was rendered nearly lifeless”—is by noting that my re-read of the chapter (see the caveat at the bottom) reveals the following:
- ZERO statements that acknowledge the main conclusion of IPCC 2007, namely that “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”
- ZERO statements that acknowledge the main conclusion of IPCC 2001, namely that “[M]ost of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations.”
- ONE statement that acknowledges the main conclusion of IPCC 1995, namely that “The balance of evidence suggests a discernible human influence on global climate.” That statement comes on p 166: “There is essentially a consensus among climate scientists that the earth’s temperature has been rising and, increasingly, agreement that human activity has played an important role.”
- ONE statement about climate science that would have looked seriously out of place ten years ago. That statement is on p 186: “Then there’s this little-discussed fact about global warming: while the drumbeat of doom has grown louder over the past several years, the average global temperature during that time has in fact decreased” (emphasis in original).
In my opinion Levitt and Dubner fail to acknowledge a decade’s worth of scientific consensus about climate change, and they compound this failure by making not-factually-incorrect-but-nontheless-terribly-misleading comments about “true believers” and “heretics” and about “agnostics [who] grumble that human activity accounts for just 2 percent of global carbon-dioxide emissions”. Put these two pieces together and I think you have an explanation for why they are getting so much push-back from folks saying that their analysis is “ideological and unscientific” and why their statement that “nothing could be further from the truth” rings hollow, at least in my ear.
PS. My caveat for the analysis above is that my eye is relatively untrained (remember that I’m an economist, not a climate scientist 🙂 and that I’ve only read the chapter two or three times.