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.

Adam Lyons

This blog to-ing and fro-ing really isn't interesting. Whilst misrepresenting a scientist - even by accident - is pretty careless, the substance of the chapter is pretty poor and contains numerous factual errors about a very important subject. What a shame.


Commenter #8: "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."

I agree with everything here, except that it is obvious that you and Levitt are NOT sincere when you say "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." That is an overwhelmingly disingenuous and juvenile argument.


Michael Roberts

The complaints are that many of your facts are under-researched or simply wrong, and that you grossly misrepresented the views of Caldeira.

Worse, you have ignored the specific and sharpest criticisms and are instead pointing fingers back, calling it smear campaign.

If you wish to address a scholarly audience rather than a sensationalist poplar one, you would do much better by squarely addressing the meat of your critics issues and questions.

On substance, so far you're losing this battle...

Michael Donohoe

Wow - if this is the response to one unpublished chapter - I can only imagine how good the other ones should be :)

Brad Fregger

The misrepresentations are much more on the side of human-caused global warming than visa versa.

However, the main problem I see here is the suggestion that we should do something to try and cool down the planet. The author, says, "... figuring out how to cool the Earth if indeed it becomes catastrophically warmer," while I don't completely disagree with this statement, it does cause me great concern.

Anyone, whose done any research into the history of climate change knows that global cooling has been much more disastrous to humanity than global warming ever has. In fact, the global warming that has existed for the past 10,000 may well have been the catalyst that has made our modern civilization possible.

Alternatively, ice ages are not happy times. Even in modern times many more have died from the cold than have ever died from it being too warm. Interestingly, the warmest summer in recorded history in central Texas happened over three quarters of a century ago, when Austin suffered 69 days in a row of temperatures over 100 degrees ... it didn't make the papers (and they didn't even have air conditioning back then). It appears we have become whimps.

So ... it scares me when the option of trying to cool the earth comes up. ... We just might be too successful.



It's pretty pathetic that even after this thorough explanation, there are those who refuse to see common sense and will continue to spout lies about your work.

I'm impressed to hear about how much work you did to ensure that this book was accurate. I wasn't going to buy it before, but I just ordered it on amazon. Thank you.

Michael Mills

Steven Levitt on NPR yesterday: "I'm not a scientist and Steven Dubner's not a scientist either, but we've managed to interact with some of the greatest scientists in this country. I think what we conclude is that the nature of the debate is just completely wrong. The real problem isn't that there's too much carbon in the air. The real problem is it's too hot."

Scientist Ken Caldeira: "If we keep emitting greenhouse gases with the intent of offsetting the global warming with ever increasing loadings of particles in the stratosphere, we will be heading to a planet with extremely high greenhouse gases and a thick stratospheric haze that we would need to main more-or-less indefinitely. This seems to be a dystopic world out of a science fiction story. First, we can assume the oceans have been heavily acidified with shellfish and corals largely a thing of the past. We can assume that ecosystems will be greatly affected by the high CO2 / low sunlight conditions — similar to what Earth experienced hundreds of millions years ago. The sunlight would likely be very diffuse — maybe good for portrait photography, but with unknown consequences for ecosystems."



@ Jason.

The term "global cooling" referred to the hypothesis in the 70's that said atmospheric aerosols would reflect sunlight and cool the earth.

So despite any political charge, it is the correct term to describe Caldeira's climate engineering project.

@ all

Whether or not climate engineering is a good idea is not the purpose of this particular blog post. This post is to address the specific claims by Romm and ClimateProgress that Levitt and Dubner lied about Caldeira's position and denied global warming is occurring. These two particular claims by Romm and others are plainly false.

Let any other criticisms of climate engineering stand on their own. It isn't the purpose here to respond to those criticisms. Those criticisms are all sorts of valid.


All pretty useless.

It's time for the influential and responsible adults of the world to push forward with non-polluting strategies of all kinds.

Why don't you join in?

Thomas K

Is this chapter available somewhere for reading before the book is released? I keep seeing snippets here and there, but I get the feeling that the critical blog posts are just attacking straw men.


How dare you write the words of "Global Cooling"!!!1!
They Are words of faith that as climate deniers you can never understand.!!

It seems like a bunch of Cardinals of the Climate Vatican didn't like that you were questioning the orthodoxy. I don't know what people would expect otherwise from contrarians such as yourselves.

What we've learned from this tale is that climate scientists like Cardiera are saying much different things to people when being candid, then when they're under pressure from the Climate industry. He is now not credible for either side on this issue, he's willing to say and confirm things with you that he later denies. Sounds like someone had his funding threatened.

As for the criticism from Big Climate: It's mostly based on the lies of Cardiera and false assumptions.

Take Krugman for example, he's been waiting for anyone to even insinuate that global socialism isn't the only solution to carbon pollution. I'm glad you did, and that your responses are not a mea culpa.

Also, consider the source of your dissent:

Krugman - Keynesian
Klein - Recent wrote a post called "Obama promises improvement, not change"
Yglesias - Practically the Rush of the Left
UCS is an unlabeled socialist lobby group

When they can't attack the message they'll attack the person.



You still havent addressed the reported error in your book where you say the main problem with solar cells is that they are black, despite actual solar cells being blue.

Eric H

Wow... You've had a busy weekend!

Thorstein Veblen

You guys have not defended yourselves against many of the charges which have been laid against you.

You assert in the book that "over the past few years, global temperatures have decreased." This is patently false. You have (wisely) chose not to defend it. It has been charged that you made at least three inaccurate statements about solar panels, you have replied to none of them. It has been asserted that you provided inaccurate forecasts of the consensus estimates of the rise in sea levels, I see no defense of this above.

Here are three more critiques of the chapter than you need to defend which may not have been mentioned elsewhere: In order to show that global temperatures were cooling into the 1970s, you use 1945 as the base year. That would be 1945, which was much hotter than both 1944 and 1946, and much much hotter than every year from 1880 to 1943. Using that one special outlying year as a base year to show a temperature decline is not quite lying exactly, but it falls into the category of "willfully misleading your readers". Most charts I've seen suggest that the 1960s and 1970s, while cooler than 1945, were actually warmer than the 1950s, the 1930s, 1920s, and much warmer than the 1910s or 1910s. And, of course, China and India have only been industrializing since about 1980, during which time the Earth has gotten much warmer.

Second thing: can I see your citation for where Al Gore tells everyone to "give up" their air conditioning? You make it sound as though he actually proposed this as a solution. Or did he just point to air conditioning as a cause of global warming, and as an example of something which might need to be curtailed?

Third thing: Many climate scientists are deeply uncertain about the impact of using aerosols to cool the planet. They say they have no idea what might happen. You did not include any of their reservations in your chapter... Instead, your bogeyman is the supposedly a-scientific Al Gore, with whom the vast majority of the scientific community actually agree with on this issue.


Neil B ?

There are many logical fallacies in the Myhrvold and Caldiera taking points that I've seen. One is the silliness of thinking that an increase in the *average* doesn't matter if the variation is larger than that. Another is the idea that even if the temperatures have trended lower recently, it indicates much. No, just think about how the temperatures fluctuate up and down as we move from season to season. A decade is too variable for long-term trends (roughly the same as using a ten-day period, to pretend to disprove the effect of the Earth's axis on climate ...) Of course, there's the fundamental theoretical issue of the absorption of IR by CO2, something the trend-fixated skeptics often ignore.

Also, here's a fundamental problem with the way these Lomborgian skeptics argue: they'll say first that the effects of what we're doing now is not all that bad, but then say "it's too late" to do anything because there's already so much CO2 out there, etc. Well: if the effect is small now, then stopping a really big increase in CO2 would be well worth it and doable, since the goal is more modest (say, preventing from reaching 800 ppm instead of say 500.)

But if the effects are already great, then: 1.) they have to admit the effect is already large, and 2.) it would still be worth doing for future generations, to help prevent from absolutely horrible outcomes. Otherwise, they sound like people saying "It's too late to stop the epidemic since it will still kill half the population even if vaccinate everyone now at great cost" - so go ahead and let 90% die?

White and dark: for one thing, they ignore non-visible reflection - like leaves reflecting lots of IR. Also, a few more leaves and solar cells (in particular!) don't affect albedo that much. However, if we used white roofs (as Energy Secretary Chu suggests) and lighter roads etc., that could make a difference.


L. Carey

Gosh, forgive me, but it's somehow hard to see how being called out by multiple credible folks (well beyond Joe Romm, and including the Union of Concerned Scientists, the unflappable William Connelley, Paul Krugman, Ezra Klein, etc.) for making a series of lazy, misleading and often simply erroneous "counterintutive" statements regarding the best response to an issue of worldwide importance (i.e., does the threat of climate change demand a global effort to mitigate CO2?) constitutes a "smear".


I'm going to harass all my friends into buying a copy and give everyone I know a copy as a Christmas gift. I encourage you all to do the same. These men are not blinking in the face of a near-lynching, and that's admirable. It's a rare opportunity to be able to support a real cause like this.

Paul Klemencic

To the posters trying to defend Levitt and Dubner...

Have you guys read page 187 of SuperF ? The number of lies and distortions and outright scientific errors is almost unbelievable. Quoting Mhyrvold as an expert in thermodynamics and heat transfer is laughable... an undergrad ChemE or MechE could easily see that the statement about the thermal energy re-radiated by solar panels as a significant global warming issue is clearly wrong.

Even the best power plants reject half or more of the thermal energy to the environment, but this thermal energy is insignificant compared in the global energy balance. Further, CO2 ends trapping over 100,000 times the thermal energy released by burning carbon to CO2. Mhyvold's energy analysis would get a failing grade in any undergrad science course. Anyone trained in doing energy balances, and understanding the science behind the energy industry would have spotted this howler a mile off. Mhyrvold seems to suffer from PowerPoint superficial analysis syndrome.

Here is a critique of that page in SuperF:

Levitt and Dubner need to save what is left of their reputations and get the publisher to pull the book. Next time, they need to have more creditable and knowledgeable people in the fields they write about, review their material.


pete best

This is not funny anymore and as the science of AGW states and continues to state this analysis is just plain incorrect and at worst wrong.

The Goddard Institute of Space Studies might know a thing or two about AGW and how to remedy it but hey - what could they know eh. Well put it this way, a damm sight more physics, chemistry, biology and the global earth system that anyone here does and hence I will take their word for it every time!!!


The NY Times blog message boards are full of the same people who worked as extras in the old Frankenstein movies, You know the ones - with the pitchforks and torches? When the mob gets worked up, they have to tear down something.