Global Warming in SuperFreakonomics: The Anatomy of a Smear

1. Let the wild rumpus start.
Yes, it’s an ancient cliché: a lie can travel halfway around the world while the truth is putting on its shoes. But it’s still accurate.

The final chapter in our forthcoming book, SuperFreakonomics, is about global warming: the risks, uncertainties, misperceptions, and proposed solutions. It has already come in for steep criticism by, among others, a prominent environmental blogger and a well-known environmental advocacy group. Their criticism has radiated into the blogosphere, producing many further stories with headlines like “SuperFreakonomics Gets Climate Change Super Freaking Wrong.”

They have given the impression that we are global-warming deniers of the worst sort, and that our analysis of the issue is ideological and unscientific. Most gravely, we stand accused of misrepresenting the views of one of the most respected climate scientists on the scene, whom we interviewed extensively. If everything they said was actually true, it would indeed be a damning indictment. But it’s not.

2. What we actually say in the book.
Our global-warming chapter has several sections. 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. We discuss how even the most sophisticated climate models are limited in their ability to predict the future, and we discuss the large measure of uncertainty in this realm, given that global climate is such a complex and dynamic system. We discuss some of the commonly held misperceptions about climate and energy, including the fact that the historic relationship between global temperature and atmospheric carbon dioxide is more complicated than is generally thought.

The real purpose of the chapter is figuring out how to cool the Earth if indeed it becomes catastrophically warmer. (That is the “global cooling” in our subtitle. If someone interprets our brief mention of the global-cooling scare of the 1970’s as an assertion of “a scientific consensus that the planet was cooling,” that feels like a willful misreading.) To think we are “deniers,” would obviate the chapter’s central point: if we weren’t convinced that global warming was worth worrying about, we wouldn’t have written a chapter about proposed solutions.

The core of the chapter concerns Intellectual Ventures, a Seattle-based invention and patent company headed up by Nathan Myhrvold. While I.V. employs several climate scientists, it generally operates outside the climate-change establishment. We present I.V.’s views on climate change in general, the limitations and costs of carbon mitigation, questions about the scalability of alternative energy sources, and the company’s proposed global-warming solutions.

The most controversial of these solutions – a “stratoshield” — involves the controlled injection of sulfur dioxide into the stratosphere to cool ground temperatures, which mimics the natural cooling effects of a big volcanic eruption like Mount Pinatubo. This sort of “geoengineering” solution is intensely disliked within environmental circles, and we discuss the reasons why. And we discuss why, if global warming gets worse, it might still be a good idea to consider further research on the stratoshield. We also discuss a much more environmentally friendly anti-warming solution from I.V. that uses salt-sea spray to increase cloud reflectivity.

3. Where this material came from
We visited Intellectual Ventures in early 2008 for a daylong discussion with roughly a dozen of its scientists and inventors. Among them were Myhrvold and Ken Caldeira, who, as we write, “is among the most respected climate scientists in the world, his research cited approvingly by the most fervent environmentalists.”

Caldeira is featured throughout the chapter. Here is how we characterize his view of global warming and carbon emissions:

“Caldeira is thoroughly convinced that human activity is responsible for some global warming and is more pessimistic than Myhrvold about how future climate will affect humankind. He believes ‘we are being incredibly foolish emitting carbon dioxide’ as we currently do.”

We also explain how some of Caldeira’s research and views complicate the common views on atmospheric carbon dioxide. These include:

  • As greenhouse gases go, carbon dioxide isn’t particularly efficient, and furthermore is governed by the law of diminishing returns.
  • The level of atmospheric carbon dioxide isn’t as meaningful a yardstick as is commonly perceived. “There’s nothing special about today’s carbon-dioxide level,” Caldeira says, “or today’s sea level, or today’s temperature. What damages us are rapid rates of change. Overall, more carbon dioxide is probably a good thing for the biosphere – it’s just that it’s increasing too fast.”
  • Also, we write: “As much as Caldeira personally lives the green life – his Stanford office is cooled by a misting water chamber rather than air-conditioning — his research has found that planting trees in certain locations actually exacerbates warming because comparatively dark leaves absorb more incoming sunlight than, say, grassy plains, sandy deserts, or snow-covered expanses.”

We describe how when Caldeira first heard about the stratoshield from Lowell Wood, another I.V. scientist, he “disliked the concept” but nevertheless “ran a climate model to test Wood’s claims.” Furthermore: “his model backed up Wood’s claims that geoengineering could stabilize the climate even in the face of a large spike in atmospheric carbon dioxide, and he wrote a paper saying so. Caldeira, the most reluctant geoengineer imaginable, became a convert — willing, at least, to explore the idea.”

That is why Caldeira was in the room with his I.V. colleagues that day – talking to us, exploring the idea – and that is one reason that we gave as much credence to I.V.’s climate and geoengineering proposals as we did: because Ken Caldeira is not a climate-change-denying know-nothing, but quite the opposite. Because even though Caldeira would like to see us become a zero-carbon society, he seemed to agree with Nathan Myhrvold’s assessment that if global warming is as real a problem as they think it may be, then an overreliance on carbon mitigation may be “too little, too late, and too optimistic.”

How could a devoted environmentalist who wants a zero-carbon society believe this? Because, as we wrote (with input from Caldeira), “the half-life of atmospheric carbon dioxide is roughly one hundred years, and some of it remains in the atmosphere for thousands of years. So even if humankind immediately stopped burning all fossil fuel, the existing carbon dioxide would remain in the atmosphere for several generations.”

After the day we spent at I.V., our further research included hundreds of follow-up inquiries with a number of its scientists, including Caldeira, via phone, e-mail, and face-to-face interviews. The supporting scientific literature is cited in the endnotes of the finished book, on pages 250-255.

4. So what happened next?
As part of our fact-checking procedure, we asked Myhrvold, Caldeira, Wood, and others to review the first draft of our chapter and give us any and all feedback and corrections. We incorporated many of their suggestions into our next draft. For instance, following a sentence we had written saying that “[Caldeira’s] research tells him that carbon dioxide is not the right villain in this fight,” Caldeira had added the following qualification:

“My views differ significantly from Lowell’s and Nathan’s. I do think we are being incredibly foolish emitting CO2 and that avoiding all of this environmental risk is a good way to invest a few percent of our GDP. My pessimism stems from the apparent difficulties of solving the ‘prisoner’s dilemma,’ ‘tragedy of the commons’ type aspects of this problem.”

As noted above, we incorporated this sentiment into the text.

We also sent an amended draft to I.V. for further feedback, and incorporated a further round of small changes.

So given this back and forth, it was pretty strange when, last week, a blog post on appeared with this headline:

“Error-riddled ‘SuperFreakonomics’: New book pushes global cooling myths, sheer illogic, and ‘patent nonsense’ – and the primary climatologist it relies on, Ken Caldeira, says ‘it is an inaccurate portrayal of me’ and ‘misleading’ in ‘many’ places.”

The post’s author is Joseph Romm, the editor of, which is “dedicated to providing the progressive perspective on climate science, climate solutions, and climate politics.”

It is not surprising that someone in Romm’s position might disagree with much of what we wrote about global warming. In this first post – he has since written several more – he had some particularly dismissive things to say about Nathan Myhrvold’s dismissal of solar power as unscalable. (More on that soon, in a following post.)

But more broadly, he made it sound as if we had distorted Ken Caldeira’s views in the worst way: “He [Caldeira] has responded to many e-mail queries of mine over the weekend,” Romm wrote. “He simply doesn’t believe what the Superfreaks make it seem like he believes.”

This was the blog post that launched a thousand more. The headlines varied a bit but the general thrust, perhaps inspired by Romm’s exciting headline, was always the same: two guys who aren’t climate scientists wrote a book with a chapter about climate science and one of the main climate scientists in this chapter is saying they badly misrepresented his views.

Yikes. If that were true, I would come after us with pitchforks too.

5. So what really happened?
Last week, a few days before Romm’s post, Caldeira sent an e-mail to Myhrvold and cc’d me as well. It included a chain of earlier e-mails between Caldeira and Romm.

The chain begins with Joseph Romm telling Caldeira that he had read SuperFreakonomics and “I want to trash them for this insanity and ignorance.” Romm adds that “my blog is read by everyone in this area, including the media” and tells Caldeira that “I’d like a quote like ‘The authors of SuperFreakonomics have utterly misrepresented my work,’ plus whatever else you want to say.”

I understand that blogging, especially advocacy blogging, doesn’t operate under the rules of journalism (where you don’t feed quotes to people), but still: that’s quite a quote to feed to someone.

Caldeira didn’t give him the quote. He did, however, respond point-by-point to a series of statements about him in the book. “The only significant error,” he wrote to Romm, “is the line: ‘carbon dioxide is not the right villain in this fight.’ That is just wrong and I never would have said it. On the other hand, I f&@?ed up. They sent me the draft and I approved it without reading it carefully and I just missed it. I think everyone operated in good faith, and this was just a mistake that got by my inadequate editing.”

Romm still managed to get his point across, in the headline and elsewhere:

“One sentence about Caldeira in particular is the exact opposite of what he believes (page 184): ‘Yet his research tells him that carbon dioxide is not the right villain in this fight.’ Levitt and Dubner didn’t run this quote by Caldeira, and when he saw a version from Myhrvold, he objected to it.”

Except of course Caldeira did see that line, and the rest of the chapter too, not once but twice.

But that didn’t seem to matter. While Romm’s post never actually delivered the Caldeira quotes teased in the headline – that it was “an inaccurate portrayal of me” and “misleading” – the point was clear to any reader: everything SuperFreakonomics says about global warming must be wrong because the main climate scientist they write about has refuted what he said. It’s hard to blame the bloggers who subsequently repeated this story: if you didn’t know it was false, it would have seemed pretty newsworthy. It’s also hard to misinterpret what’s going on here. Now that global warming has transcended science to become a political issue, the rules of politics apply: if you don’t like someone’s position, attack their credibility.

I understand why Caldeira now feels that the “villain” line overstates his position. I certainly wish we had discussed amending it earlier, and it’s probably a good idea to change that line in future editions of the book. That said, why did Romm think that Levitt and I had distorted his views throughout? I wrote to Caldeira to ask him this, and he replied: “I do think there are a bunch of things in the chapter that give misimpressions.” In a later e-mail, he explained further:

“I was drawn in by Romm and Al Gore’s assistant into critiquing other parts of the chapter. Rather than acting deliberately, I panicked and commented on things that I now wish I would have been silent on. It was obviously a mistake to let myself get drawn into this, and I learned a quick and hard lesson in public relations.”

Caldeira then sent along another, more recent e-mail he’d written to a British journalist who asked for comment on his portrayal in SuperFreakonomics. “I believe all of the ideas attributed to me are based on fact, with the exception of the ‘carbon dioxide is not the right villain’ line,” he wrote. “That said, when I am speaking, I place these facts in a very different context and draw different policy conclusions.” He added that “I believe the authors to have worked in good faith. They draw different conclusions than I draw from the same facts, but as authors of the book, that is their prerogative.”

6. There is much more to be said.
Levitt and I – and Nathan Myhrvold, and maybe even Ken Caldeira – look forward to debating the content of the chapter itself, the actual ideas and conclusions.

Will a lot of people argue with them? Absolutely. Some critics claim that we are too pessimistic about carbon mitigation, that we understate the probability of catastrophic climate change, that we are wrong to write that “the movement to stop global warming has taken on the feel of a religion.” Fair enough: we will debate those issues.

But it would be good if the debate were inspired by the content of our chapter rather than a partisan attack built around a faulty central premise: that we twisted a leading climate scientist’s words to suit our own purposes. After all, if the idea is to actually fight global warming, doesn’t it make sense to think about solutions beyond carbon mitigation?

Much of the outcry was made by people who had read Romm but not our book — which isn’t surprising, since the book isn’t out until October 20. As the noise grew, Romm added on the charge that
“the publisher has stopped Amazon from allowing people to search the book” – that is, to read the actual text online. Smells like a conspiracy theory, no?

But nobody stopped anything. The text was never searchable on Amazon for the simple reason that the book wasn’t yet published, which is standard procedure. I don’t know where Romm got this fact – or if perhaps it was just too good a rumor to not be true.

It’s an easy bet that Romm and others like him will keep it up. That’s their job. We should probably sleep with our shoes on for a while.

[ADDENDUM (Oct. 21, 2009): It turns out I was wrong when, two paragraphs above, I wrote above that “the text was never searchable on Amazon.” I had asked our publisher if the book had been searchable prior to publication and was told the answer was no. But a few days after I wrote this post, the publisher informed me that I’d been given wrong information. Here’s a statement from them:

“Stephen Dubner asked us if his book SuperFreakonomics had been posted on Amazon Search Inside the Book, and we told him it hadn’t been,” said a HarperCollins spokesperson. “But the search function was accidentally enabled for a brief time last week. As soon as we saw this, it was disabled because it is generally our policy not to allow search until after the book goes on sale.”

I apologize for this error, and especially to Romm for the accusation. (To our friends at Harper who fed me the wrong information — I know who you are and, believe you me, I’ll be stuffing your Christmas stocking with some lumps of coal non-carbon heating fuel.)

Now that the book has been published, the Amazon page is searchable.

Marion Delgado

The smear merchants are you, not the scientists and supporters of science who are pointing out your errors, omissions, distortions and fabrications.

Gavin Schmidt

With all due respect, the text at Amazon was indeed searchable at the time Romm posted his first post. It is not now. No conspiracy mongering, just observation.

However, possible misquotes of Caldeira are the least of the problems with this chapter as William Connolley and Tim Lambert have shown.

My take is here:


7. There is much more to be said.


Anyone reading this and Romm's comments, who doesn't see how this topic has become a sort of religion for many, just isn't paying attention.

As I think you're trying to demonstrate (haven't read the book, or course), this is a complex subject with room for debate and further research, if not on the fact of climate change, at least on the proposed solutions.

I'm not a 'denier', but I'm always suspicious of the cry "We must act now!" when even the most aggressive proposals won't mitigate the changes we're seeing for fifty years or so.


Me thinks they dost protest too much. Clearly, if the thought leaders of the climate change movement are so quick to debase solutions outside of complete economic control, one has to question their true motivations. Keep it up.


Maybe you could respond to critiques of your presentation of the science of climate change: See William Connolley, a former climate modeler at the British Antarctic Survey who often disagrees with Joe Romm on climate change issues:


I will give you some irrefutable evidence and then let you decide what to think about global warming:
Humankind has long witnessed periods of time marked by the rise of new cultural, religious, and political movements. Well known examples (to the Western world) include protestantism, the renaissance, the inquisition, the industrial revolution, socialism, etc. I don't know the answer to this question but I think it is a fair one: Is the global warming movement about science, religion, politics, or a little of all three?


I don't have the expertise to evaluate any of the substantive issues, but even after reading the chapter I took the "Global Cooling" in the subtitle to refer to the anecdote about scientific beliefs in the 1970s and NOT to the proposed geoengineering project.

The problem is that the term "Global Cooling" is a well-established one in the discourse on climate change, routinely used by conservative commentators to disparage those who point to a scientific consensus on global warming. I'm sure you are sincere when you say this was not your intention, but the fact remains that this is the clear interpretation of the term in the context of the global warming debate. If this was not your intention, the subtitle should be altered in future editions.


No,no,no,no---you have committed apostasy; heresy! You are not allowed to speak of warming except in the most emotional, alarmist tones!

You are not allowed to follow an objective, skeptical line of reasoning in this matter. You are not allowed to consider whether or not it is cost-efficient or even possible to cease all carbon emissions, you simply must do it. You must shun all otherwise-intelligent people who think maybe warming may have some benefits that might, just might offset the problems.

But you guys have absolutely guaranteed that you will sell a ton of books. I already have my order in and I hope that "SuperFreakonomics" generates an honest, open discussion on the topic that causes all sides to reconsider their position. Well done.

Dan Hue

I believe it is Henry Ford who said (and I paraphrase) "Whether you think you can do something or don't, you are right.". You don't think mitigation of AGW is feasible, but others (e.g., Romm, Krugman) believe it is, and is probably much easier (and less costly) than most people think. The day we have to spray sulfur dioxide into the atmosphere to counteract catastrophic climate change is the day we certainly have to be actively pursuing reducing CO2 emissions. As a plan B, insurance policy kind of thing, sure, let's study geoengineering. But not as a primary solution.


You guys are extremely defensive on this topic which makes me think you know you sort of screwed up with taking the whole "contrarian" think too far in a subject where you know far too little.

You are trying to smear people like Krugman, Yglesias, Romm, et al, but frankly, they're much, much more credible on this topic than you, and your rebuttals to their claims are not the least bit convincing.


You concede that your primary source for the chapter (Ken Caldeira, "one of the most respected climate scientists on the scene") says that “I do think there are a bunch of things in the chapter that give misimpressions.” It sounds to me like he is - in a polite academic way - saying that you are misrepresenting his views.

John Doe

What's really ironic and hilarious about your critics is that some of them seize on the line that global warming is occasionally treated as a religion, and they then use that line to excoriate you as a damnable heretic.


Congrats! You have generated enough controversy to guarantee millions from book sales! What more do you want? Didn't you talk about "incentives" in your earlier book?

And of course, now you also have ultra right-wing fanboys on your side! They can now use their pea-size brains to post comments everywhere and fan this controversy even more.

Tim Lambert

You can certainly draw different policy implications from Caldeira's work than him, but you claimed that he drew the same ones as you. I quote:

"It is one thing for climate heavyweights such as Crutzen and Caldeira to endorse such a solution."

Caldeira has not endorsed your solution (and neither has Crutzen for that matter).


If Romm has indeed done some of the things you have mentioned, I find it inexcusable. And as someone who works in the field I've found his approach to be at times divisive and ultimately counterproductive.


Good job.


It's not a smear. You wrote a superficial chapter about a complex subject, quoted people who aren't even climate scientists, picked one perspective and presented that as fact. You wrote a mediocre magazine article, one not worthy of The New Yorker because it lacks facts, balance and solid discussion. You deserve the criticism.

And then you put garbage words on the cover of your book. On the cover of your book. Repeat: you chose to put garbage words on the cover of your book.

Leszek Pawlowicz

This is it? This is your response to the substanstive criticisms of Paul Krugman, Ezra Klein, Matt Yglesias, the Union Of Concerned Scientists, William Connelly, RealClimate.Org, and many others? Lame. Totally lame.


Keep up the good work, guys!
When scientists refuse to even examine alternate proposals or points of view, they cease being scientists. Leave the smearing to the politicians.