A little while ago, I wrote about the “the globe is currently cooling” myth, which, unfortunately, was propagated in Steven Levitt and Stephen Dubner’s new book, SuperFreakonomics. As I explained earlier, I was big fan of their earlier book, Freakonomics, which is why I was disappointed to learn of their unfortunate mistake. I also linked to two criticisms of Levitt and Dubner’s chapter on global warming (which can be read here). A lot has happened since then.

Most recently, Dr. Levitt wrote a blog post at the Freakonomics blog defending the chapter. Mr. Dubner also wrote a post defending the chapter and going after one of the main criticizers, Joseph Romm. Dr. Romm wrote one of the original critiques (which I linked to in my previous post, along with Dr. Connolley’s), pointing out errors and Levitt and Dubner’s misrepresentation of the main scientist they used for their chapter. The links I’ve just provided here provide plenty of background to the controversy as well links to other posts surrounding the ill-fated chapter, including responses by Nobel laureate Paul Krugman, Union of Concerned Scientists, Tim Lambert, Gavin Schmidt of NASA, and plenty others.

The gist of the controversy, from I found sifting through the countless attacks and defenses of the chapter, is that Levitt and Dubner misrepresented Ken Caldeira, the main climate scientist they refer to in their chapter; make several errors in their analysis of the science; and advocate geo-engineering (pumping sulfate aerosols into the atmosphere) as opposed to greenhouse gases reductions as the preferable way to mitigate the effects of anthropogenic global warming. For a more thorough understanding of the controversy, visit some of the links I’ve posted above as well as the links the authors of those posts provide. From my perspective, it seems that Levitt and Dubner have chosen the contrarian position and pushed forward shocking conclusions because, frankly, that’s one way to become bestsellers. Unfortunately, there was a not a lot of room for mistake and errors were certainly made. The barrage of criticism across the Web has been unrelenting as a result.

But what is the core issue, particularly as the book deals with it? The core issue here, as I see it, is the best way to deal with the climate crisis (which everyone agrees exists). Levitt and Dubner advocate geo-engineering as the solution, as a means to reflect sunlight and thus reduce global mean temperatures. They say it is a quick and cheap solution. On the other hand, they disagree with lowering emissions because it is a long and difficult process that could cost what they say is thousands times more than their solution. (Part of the disagreement is that Dr. Caldeira is very much for eliminatation of carbon emissions and supports research into geo-engineering, which is not reflected in the book.) As Dr. Levitt points out, the question they’re answer is, What is the cheapest and fastest way to cool the Earth? He says environmentalists and scientists are asking other questions: “The sorts of questions they tend to ask are ‘What is the “right” amount of carbon to emit?’ or ‘Is it moral for this generation to put carbon into the air when future generations will pay the price?’ or ‘What are the responsibilities of humankind to the planet?’

Is it the case that geo-engineering is the correct solution while reducing greenhouse gas emissions is not? It’s doubtful. Dr. Caldeira argues that our emissions are necessarily wrong: “I compare CO2 emissions to mugging little old ladies … It is wrong to mug little old ladies and wrong to emit carbon dioxide to the atmosphere. The right target for both mugging little old ladies and carbon dioxide emissions is zero.” So already we see that Dr. Caldeira is very much opposed to greenhouse gas emissions, though SuperFreakonomics claims, “Yet his research tells him carbon dioxide is not the right villain in this fight.” Quite preposterous. Dr. Caldeira continues in his e-mail to Dr. Romm:

I am in favor of fire insurance but I am also against playing with matches while sitting on a keg of gunpowder. I am in favor of research into geoengineering options but I am also against carbon dioxide emissions.

Carbon dioxide emissions represent a real threat to humans and natural systems, and I fear we may have already dawdled too long. That is why I want to see research into geoengineering — because the threat posed by CO2 is real and large, not because the threat is imaginary and small.

The problem that Levitt and Dubner fail to account for is that greenhouse gas emissions are responsible for many changes besides just temperature increases. That’s why “climate change” is becoming a more popular term than “global warming.” Warming is just one aspect of it. The effects our actions have on climate are broad, including ocean acidification, changes in rainfall patterns, extreme weather events, and so on. While pumping sulfate aerosols into the stratosphere may take care of the temperature problems, it neglects a whole host of issues that are caused by human activity. Furthermore, the proposals Levitt and Dubner make are likely to have their own negative effects as well as technical and strategic issues. Writes Dr. Schmidt, “if the planet was a single column with completely homogeneous properties from the surface to the top of the atmosphere and the only free variable was the surface temperature, it would be fine. Unfortunately, the real world (still) has an ozone layer, winds that depend on temperature gradients that cause European winters to warm after volcanic eruptions, rainfall that depends on the solar heating at the surface of the ocean and decreases dramatically after eruptions, clouds that depend on the presence of condensation nuclei, plants that have specific preferences for direct or diffuse light, and marine life that relies on the fact that the ocean doesn’t dissolve calcium carbonate near the surface.” Add to that “unknown unknowns” and it seems the geo-engineering proposal is not the cheap or desirable solution it was made out to be.

What about reducing emissions? Claims Dr. Levitt, “a third problem with reducing carbon emissions, which is that it requires worldwide behavioral change, which will be hard to achieve.” Why is that the case? Mr. Dubner explains, “We discuss how it’s a very hard problem to solve since pollution is an externality – that is, the people who generate pollution generally don’t pay the cost of their actions and therefore don’t have strong incentives to pollute less.” Well then… make them pay the cost of their actions! I wrote earlier that global warming represents the greatest market failure ever. The solution is that you correct for that market failure, meaning people pay for the consequences of their actions. Dr. Stern explains, “People would pay a little more for carbon-intensive goods, but our economies could continue to grow strongly.” Dr. Levitt, I’m sure, knows that behavioral change is not that hard, especially when we realize that people respond to incentives—a core economic principle (and the center of their first book). Right now, the cost of emitting greenhouse gases is far less than the actual cost of doing so, meaning there is little (economic) incentive to stop engaging in carbon-intensive activities. As Dr. Schmidt points out, the problems of lead in gasoline and CFCs in spray cans were solved by increasing the costs of these things, which has led to the elimination of both. Nothing says we can’t do the same for greenhouse gas emissions.

Update: Indeed, Dr. Levitt is fully aware. Here’s a quote from Chapter 3: “People are people, and they respond to incentives. They can nearly always be manipulated — for good or ill — if only you find the right levers.”

Update2: Brian Dupuis has a collection of links that may be helpful in following the controversy.