The Freakonomics guys have apparently either really dropped the ball when it comes to understanding science, or they're willfully ignoring it. Either way, I'm pretty disappointed.
The sequel's contrarian take on climate change–and the bad science it's steeped in–have been analyzed in exquisite detail by everybody from Paul Krugman, Berkeley economist J. Bradford DeLong, to the Union of Concerned Scientists, to various climate scientists spread hither and non about the Web.
That's a lot of links, but they're there so you can go back and read page-by-page breakdowns of the mistakes and inaccuracies, by experts, if you want. I think that's important, because I know at least some of you are going to assume that any criticism of this book and its contents is all about some violation of pseudo-religious orthodoxy. I want you to be able to go see that this is about science. If you just want a quick summary, though, read on…
There's a lot of stuff that the chapter on climate change gets wrong, but we can break it down into three key problems.
First, Stephen Dubner and Steven Levitt argue that carbon dioxide isn't really the cause of climate change. It's not really "the bad guy". They cite Stanford climate scientist Ken Caldeira as supporting this, but Caldeira says what he actually told them was that carbon dioxide wasn't the only bad guy. And that's true. There are several gases in the greenhouse gas family and they're all a problem to varying degrees. But that doesn't mean that CO2 isn't a problem. (If you read the links, there's some journalism "Inside Baseball" about whether Dubner and Levitt knew they were misrepresenting Caldeira and, if not, what happened instead.)
Second, they make the claim that the planet has actually been getting cooler for the last 10 years and, thus, climate change projections are wrong. That idea is based on data from a single study and is contradicted in others. Either way, short-term cooling doesn't invalidate a global warming trend. Why? Because global warming isn't a straight line going up. On a graph, this is a series of peaks and valleys. Close up, on the scale of decades, the trends appear to fluctuate up and down fairly randomly. Pull back and look at the last century, though, and there is clear upward movement. It doesn't really matter how hot or cold it was this year, or in 1999. What matters is what's happening, on a grand scale, between 1900 and 2009. (This link has the best in-depth explanation.)
The last thing I'm going to talk about is Dubner and Levitt's assertion that geoengineering is a better way of dealing with climate change than any attempts to change energy use or sourcing. This one, I'm less well-versed in, particularly when it comes to the economics of such an endeavor. Although, the J. Bradford DeLong links provide some context. But let's put it this way: Geoengineering is cool, but it's a big risk. You're basically running a massive, one-time experiment and hoping the models caught all the possible consequences. Not saying it's evil. Not saying we won't maybe need to try something like that someday. But it's not exactly a first-line-of-defense kind of weapon.
So, why do I care? Well, frankly, because I really enjoyed reading the original "Freakonomics" book. Dubner and Levitt are engaging writers, and they have a big audience. And that means they have a lot of influence. Part of me would like to ignore the problems with this new book, because it kind of comes across as an attention-grabbing ploy and I hate to bite the marketing stick. But, it's factually wrong. They're influential. And so their factual inaccuracies will enter into public debate as "fact". And so I feel the need to make a big, damn long post about it.