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An open letter to Steve Levitt

Filed under: — raypierre @ 29 October 2009

Dear Mr. Levitt,

The problem of global warming is so big that solving it will require creative thinking from many disciplines. Economists have much to contribute to this effort, particularly with regard to the question of how various means of putting a price on carbon emissions may alter human behavior. Some of the lines of thinking in your first book, Freakonomics, could well have had a bearing on this issue, if brought to bear on the carbon emissions problem. I have very much enjoyed and benefited from the growing collaborations between Geosciences and the Economics department here at the University of Chicago, and had hoped someday to have the pleasure of making your acquaintance. It is more in disappointment than anger that I am writing to you now.

I am addressing this to you rather than your journalist-coauthor because one has become all too accustomed to tendentious screeds from media personalities (think Glenn Beck) with a reckless disregard for the truth. However, if it has come to pass that we can’t expect the William B. Ogden Distinguished Service Professor (and Clark Medalist to boot) at a top-rated department of a respected university to think clearly and honestly with numbers, we are indeed in a sad way.

By now there have been many detailed dissections of everything that is wrong with the treatment of climate in Superfreakonomics , but what has been lost amidst all that extensive discussion is how really simple it would have been to get this stuff right. The problem wasn’t necessarily that you talked to the wrong experts or talked to too few of them. The problem was that you failed to do the most elementary thinking needed to see if what they were saying (or what you thought they were saying) in fact made any sense. If you were stupid, it wouldn’t be so bad to have messed up such elementary reasoning, but I don’t by any means think you are stupid. That makes the failure to do the thinking all the more disappointing. I will take Nathan Myhrvold’s claim about solar cells, which you quoted prominently in your book, as an example.

As quoted by you, Mr. Myhrvold claimed, in effect, that it was pointless to try to solve global warming by building solar cells, because they are black and absorb all the solar energy that hits them, but convert only some 12% to electricity while radiating the rest as heat, warming the planet. Now, maybe you were dazzled by Mr Myhrvold’s brilliance, but don’t we try to teach our students to think for themselves? Let’s go through the arithmetic step by step and see how it comes out. It’s not hard.

Let’s do the thought experiment of building a solar array to generate the entire world’s present electricity consumption, and see what the extra absorption of sunlight by the array does to climate. First we need to find the electricity consumption. Just do a Google search on “World electricity consumption” and here you are:


Now, that’s the total electric energy consumed during the year, and you can turn that into the rate of energy consumption (measured in Watts, just like the world was one big light bulb) by dividing kilowatt hours by the number of hours in a year, and multiplying by 1000 to convert kilowatts into watts. The answer is two trillion Watts, in round numbers. How much area of solar cells do you need to generate this? On average, about 200 Watts falls on each square meter of Earth’s surface, but you might preferentially put your cells in sunnier, clearer places, so let’s call it 250 Watts per square meter. With a 15% efficiency, which is middling for present technology the area you need is

2 trillion Watts/(.15 X 250. Watts per square meter)

or 53,333 square kilometers. That’s a square 231 kilometers on a side, or about the size of a single cell of a typical general circulation model grid box. If we put it on the globe, it looks like this:


So already you should be beginning to suspect that this is a pretty trivial part of the Earth’s surface, and maybe unlikely to have much of an effect on the overall absorbed sunlight. In fact, it’s only 0.01% of the Earth’s surface. The numbers I used to do this calculation can all be found in Wikipedia, or even in a good paperbound World Almanac.

But we should go further, and look at the actual amount of extra solar energy absorbed. As many reviewers of Superfreakonomics have noted, solar cells aren’t actually black, but that’s not the main issue. For the sake of argument, let’s just assume they absorb all the sunlight that falls on them. In my business, we call that “zero albedo” (i.e. zero reflectivity). As many commentators also noted, the albedo of real solar cells is no lower than materials like roofs that they are often placed on, so that solar cells don’t necessarily increase absorbed solar energy at all. Let’s ignore that, though. After all, you might want to put your solar cells in the desert, and you might try to cool the planet by painting your roof white. The albedo of desert sand can also be found easily by doing a Google search on “Albedo Sahara Desert,” for example. Here’s what you get:


So, let’s say that sand has a 50% albedo. That means that each square meter of black solar cell absorbs an extra 125 Watts that otherwise would have been reflected by the sand (i.e. 50% of the 250 Watts per square meter of sunlight). Multiplying by the area of solar cell, we get 6.66 trillion Watts.

That 6.66 trillion Watts is the “waste heat” that is a byproduct of generating electricity by using solar cells. All means of generating electricity involve waste heat, and fossil fuels are not an exception. A typical coal-fired power plant only is around 33% efficient, so you would need to release 6 trillion Watts of heat to burn the coal to make our 2 trillion Watts of electricity. That makes the waste heat of solar cells vs. coal basically a wash, and we could stop right there, but let’s continue our exercise in thinking with numbers anyway.

Wherever it comes from, waste heat is not usually taken into account in global climate calculations for the simple reason that it is utterly trivial in comparison to the heat trapped by the carbon dioxide that is released when you burn fossil fuels to supply energy. For example, that 6 trillion Watts of waste heat from coal burning would amount to only 0.012 Watts per square meter of the Earth’s surface. Without even thinking very hard, you can realize that this is a tiny number compared to the heat-trapping effect of CO2. As a general point of reference, the extra heat trapped by CO2 at the point where you’ve burned enough coal to double the atmospheric CO2 concentration is about 4 Watts per square meter of the Earth’s surface — over 300 times the effect of the waste heat.

The “4 Watts per square meter” statistic gives us an easy point of reference because it is available from any number of easily accessible sources, such as the IPCC Technical Summary or David Archer’s basic textbook that came out of our “Global Warming for Poets” core course. Another simple way to grasp the insignificance of the waste heat effect is to turn it into a temperature change using the standard climate sensitivity of 1 degree C of warming for each 2 Watts per square meter of heat added to the energy budget of the planet (this sensitivity factor also being readily available from sources like the ones I just pointed out). That gives us a warming of 0.006 degrees C for the waste heat from coal burning, and much less for the incremental heat from switching to solar cells. It doesn’t take a lot of thinking to realize that this is a trivial number compared to the magnitude of warming expected from a doubling of CO2.

With just a little more calculation, it’s possible to do a more precise and informative comparison. For coal-fired generation,each kilowatt-hour produced results in emissions of about a quarter kilogram of carbon into the atmosphere in the form of carbon dioxide. For our 16.83 trillion kilowatt-hours of electricity produced each year, we then would emit 4.2 trillion kilograms of carbon, i.e. 4.2 gigatonnes each year. Unlike energy, carbon dioxide accumulates in the atmosphere, and builds up year after year. It is only slowly removed by absorption into the ocean, over hundreds to thousands of years. After a hundred years, 420 gigatonnes will have been emitted, and if half that remains in the atmosphere (remember, rough estimates suffice to make the point here) the atmospheric stock of CO2 carbon will increase by 210 gigatonnes, or 30% of the pre-industrial atmospheric stock of about 700 gigatonnes of carbon. To get the heat trapped by CO2 from that amount of increase, we need to reach all the way back into middle-school math and use the awesome tool of logarithms; the number is

(4 Watts per square meter) X log2(1.3)

or 1.5 Watts per square meter. In other words, by the time a hundred years have passed, the heat trapped each year from the CO2 emitted by using coal instead of solar energy to produce electricity is 125 times the effect of the fossil fuel waste heat. And remember that the incremental waste heat from switching to solar cells is even smaller than the fossil fuel waste heat. What’s more, because each passing year sees more CO2 accumulate in the atmosphere, the heat trapping by CO2 continues to go up, while the effect of the waste heat from the fossil fuels or solar cells needed to produce a given amount of electricity stays fixed. Another way of putting it is that the climate effect from the waste heat produced by any kind of power plant is a one-off thing that you incur when you build the plant, whereas the warming effect of the CO2 produced by fossil fuel plants continues to accumulate year after year. The warming effect of the CO2 is a legacy that will continue for many centuries after the coal has run out and the ruins of the power plant are moldering away.

Note that you don’t actually have to wait a hundred years to see the benefit of switching to solar cells. The same arithmetic shows that even at the end of the very first year of operation, the CO2 emissions prevented by the solar array would have trapped 0.017 Watts per square meter if released into the atmosphere. So, at the end of the first year you already come out ahead even if you neglect the waste heat that would have been emitted by burning fossil fuels instead.

So, the bottom line here is that the heat-trapping effect of CO2 is the 800-pound gorilla in climate change. In comparison, waste heat is a trivial contribution to global warming whether the waste heat comes from solar cells or from fossil fuels. Moreover, the incremental waste heat from switching from coal to solar is an even more trivial number, even if you allow for some improvement in the efficiency of coal-fired power plants and ignore any possible improvements in the efficiency of solar cells. So: trivial,trivial trivial. Simple, isn’t it?

By the way, the issue of whether waste heat is an important factor in global warming is one of the questions most commonly asked by students who are first learning about energy budgets and climate change. So, there are no shortage of places where you can learn about this sort of thing. For example, a simple Google search on the words “Global Warming Waste Heat” turns up several pages of accurate references explaining the issue in elementary terms for beginners. Including this article from Wikipedia:


A more substantive (though in the end almost equally trivial) issue is the carbon emitted in the course of manufacturing solar cells, but that is not the matter at hand here. The point here is that really simple arithmetic, which you could not be bothered to do, would have been enough to tell you that the claim that the blackness of solar cells makes solar energy pointless is complete and utter nonsense. I don’t think you would have accepted such laziness and sloppiness in a term paper from one of your students, so why do you accept it from yourself? What does the failure to do such basic thinking with numbers say about the extent to which anything you write can be trusted? How do you think it reflects on the profession of economics when a member of that profession — somebody who that profession seems to esteem highly — publicly and noisily shows that he cannot be bothered to do simple arithmetic and elementary background reading? Not even for a subject of such paramount importance as global warming.

And it’s not as if the “black solar cell” gaffe was the only bit of academic malpractice in your book: among other things, the presentation of aerosol geoengineering as a harmless and cheap quick fix for global warming ignored a great deal of accessible and readily available material on the severe risks involved, as Gavin noted in his recent post. The fault here is not that you dared to advocate geoengineering as a solution. There is a broad spectrum of opinion among scientists about the amount of aerosol geoengineering research that is justified, but very few scientists think of it as anything but a desperate last-ditch attempt, or at best a strategy to be used in extreme moderation as part of a basket of strategies dominated by emissions reductions. You owed it to your readers to present a fair picture of the consequences of geoengineering, but chose not to do so.

May I suggest that if you should happen to need some friendly help next time you take on the topic of climate change, or would like to have a chat about why aerosol geoengineering might not be a cure-all, or just need a critical but informed opponent to bounce ideas off of, you don’t have to go very far. For example…


But given the way Superfreakonomics mangled Ken Caldeira’s rather nuanced views on geoengineering, let’s keep it off the record, eh?

Your colleague,

Raymond T. Pierrehumbert
Louis Block Professor in the Geophysical Sciences
The University of Chicago

807 Responses to “An open letter to Steve Levitt”

  1. 101
    Bill D says:

    I tried searching “Superfreakonomics and climate change” and found scores of entries pointing out errors in the book. Perhaps the balance of misinformation and useful discussion and learning that comes from this incident will not be as bad as one might fear. Am I naive to think that a good proportion of people reading the book will know that the chapters on climate have been widely and forcefully debunked?

    [Response: I’d like to think that, but it depends a lot on how many people read blogs, the NYT and AP, vs. how many people watch Jon Stewart. –raypierre]

  2. 102
    Thomas says:

    Another way to look at the direct heating effect. How much would it cost to offset the extra absorption due to the solar cells? Well, paint is pretty darn cheap, $10 of white paint should be able to offset the heating from a $10,000 dollar PV array. And it is easy to apply, just mix with water and dump into the tank of a street sweeper machine. So if direct heating from dark solar plants is ever deemed to be an issue, the cost of offsetting that effect is something like .1% of the cost of the solar plant!

    Raypierre, the point about white roofs is that they are a cost effect negawatts BB. I.E. for say a tile roof like I have, add $5 worth of white paint to ten gallons of water, and apply with a mop. The net cost is so small, that the cost effectiveness is high. If you got to replace tiles, or shingles, then it will be very expensive.

  3. 103
    Marion Delgado says:

    I don’t know whether to commend Levitt for responding here – where science, not PR, reigns – or to note his despicable utter disregard for the truth, history, reality, etc.

    I guess a little of both. He’s gutsy but sociopathic. Or just so fuzzy on the concept of science that he really DOES think it’s a subset of his economic cult, for practical purposes.

  4. 104
    Marion Delgado says:

    Oh and Raypierre. This is one of the most amazing posts on realclimate, ever. It’s as solid as, say, Jeff Severinghaus’s post on “CO2 leads Temperature” but it avoids the pitfalls of expressing yourself in sciencese which weasels can spin into great uncertainty.

  5. 105
    Marion Delgado says:

    #54 Knut Witberg at 10:35 AM:

    Professor Pierrehumbert is glossing over the fact that that extra heat that is absorbed is not the problem, the problem is the forcing – the positive feedback – caused by the warming of the air. And that forcing is the controversial point in the global warming theory. Some even believe that the feedback is negative, so that a doubling of the CO2 in the atmosphere would cause much less than 1 C warmer earth. And observations since 1998 seemingly support that opinion. Time is the mother of truth…

    If you felt like that was left hanging in the air, it’s because no science I am aware of says anything remotely like what you posted, and it’s so bizarrely distant from anything anyone else is talking about that it would be hard to make a meaningful reply. For example, I personally am not even aware of anyone on the fringe of the denialist community that would say that.

    My best guess is you misunderstood that the warming of the oceans is a positive feedback because the water absorbs less CO2 as its temperature increases, and probably also something about water vapor – which is not air – as a feedback to the various forcings.

    As for the idea that either warming the air or doubling CO2 would have a negative feedback on temperature, again, no one says that. It’s as impossible for Raypierre to be glossing over that as he is to be glossing over a theory that feeding children cyanide tablets makes them better at sports. No such theory exists, or even hypothesis. And if it’s a conjecture, you’re likely to be the sole proprietor.

  6. 106
    Russell Seitz says:

    Gavin : In an articles in the New Yorker last march , Gladwell described sitting on geoengineering sessions with many of those whom Superfreakonomics cites .

    Much of the same technical ground was covered , but the New Yorker piece evoked a response as mild as that afforded a John McPhee essay.

  7. 107
    Russell Seitz says:

    Gavin :
    I git the mont wrong- Malcolm Gladwell’s Annals of Innovation piece on geoengineering , entitled ” In The Air” appeared in the May 12 2008 number of The New Yorker

    [Response: Hi, Russell. I hadn’t seen this article when it first came out, but I just gave it a hasty read right now. I didn’t see any specific mention of geoengineering in it amongst the many invention ideas discussed, but I think that even if that had been one of the examples Gladwell picked (and maybe I missed something in the 9 pages of the article) it wouldn’t be noticed as much because the article is really an observers profile of how Intellectual Ventures works, doesn’t take much of an advocacy stance, and makes it pretty clear that while some of these ideas are patentable most of them have no real chance of working. It was a very interesting and relevant profile, though, particularly as to the connection between Lowell wood and Myhrvold. That’s no doubt where Myhrvold got on his geoengineering kick, as Lowell has been a long-time geoengineering evangelist, going back to his days with Edward Teller. He talks about things like “engineering to correct the deficiencies of natural sunlight,” or “giving the entire world a Mediterranean climate,” i.e. he’s so into that he seems to think it would be something you should do even if there were no global warming looming.

    Actually, maybe the best thing that could happen to put the breaks on aerosol geoengineering would be for Myhrvold’s company to get its hands on it and lock it up with patents making it prohibitively expensive for anybody to try. There are at least some that say that Intellectual Ventures is not an innovation company but just a patent troll, and has been if anything an impediment to adoption of technological innovations (e.g. this article) It’s not clear yet whether they are trolls or not, but it’s something to watch. –raypierre]

  8. 108

    Knut Witberg posts:

    Some even believe that the feedback is negative, so that a doubling of the CO2 in the atmosphere would cause much less than 1 C warmer earth.

    For “some” read “Richard Lindzen.” The vast majority of studies find net feedback to be positive, not negative. And time since 1998 is not enough to prove anything, since you generally need 30 years to test a climate trend.

    Read and learn:

  9. 109
    Mark says:

    The posts here, with the possible exception of Mark, who always seems to speak from a position of assumed moral and technological superiority”

    Says Burgess in a position of assumed moral and technological superiority…

    If you can’t attack the words, attack the man, hmm?

  10. 110
    pete best says:

    Dear RC, a little question about your coal CO2 numbers. 420 gigatonnes of Co2 (present rates with no yearly increase?) in 100 years and sinks not failing is purely from coal burning as it presently stands is it not ?

    If we add in oil and gas contribution and everything else its still around 29-30 billion tonnes of CO2 added to the atmosphere per annum with no global increase per annum factored in.

    If I add in that 2-3% per annum increase then its a doubling of co2 emissions in (log 2 = 70) divided by 2 and 3 respectibvely or 23 to 35 years which is just a little frightening for accorsding to my rough spreadsheet calculations its an additional 1.5 trillion tonnes of CO2!!!

    With sinks potentially faltering and emissions incresing 1 trillion tonnes of CO2 could be added to the 200 billion tonnes already emitted by the middle of the century!! Thats a 5 fold increase !!

    I then looked into a 2-3% per annum decrease then it makes a lot more sense and Co2 emissions are reduced to around 500 to 600 billion tonnes which is far less alarming but still will incur some additional warming and double our present additional atmospheric emissions to >450 ppmv.

    Am I on the right track here? If so then can’t we combine geoengineering in some way with carbon mitigation to put a ceiling on temperature rises in order to even stand a chance of mitigating AGW to manageable levels ?

  11. 111
    Mark says:

    “A year ago I suggested to three of my colleagues, one a geophysicist, another a professor of statistics and a third recently retired from a top engineering job at GM. All three have since expressed to me their rejection of the site BASED ON THE COMMENTS.”

    Odd how so many people seem to have been “believers” (and they do use that phraseology) but turned off because the idiots spouting rubbish were shown they were spouting rubbish and called idiots.

    Yet NOT ONE has gone the other way…

    It would seem if this story (for this is all this tale is: a story to frighten) is true then denialism is much like the Church of Scientology or indeed any other cult.

  12. 112
    Jeffrey Davis says:

    In the calculation:

    (4 Watts per square meter) X log2(1.3)

    where does the 1.3 come from?

    [Response: That’s the ratio of the amount of CO2 in the “final” atmosphere to the amount of CO2 in the pre-industrial atmosphere (it comes from my very rough estimate of an increase by 30% from the base value). It comes The “4” out front is from the stat that each doubling gives you 4 Watts per square meter of radiative forcing. So, log2(2) = 1, and
    you get 4 Watts per square meter, another doubling takes you to 4X preindustrial CO2, which yields log2(4) = 2, and hence 8 Watts per square meter, etc. You can think of the log2 in there as a way of interpolating between even doubling values, respecting the radiative physics of CO2. –raypierre]

  13. 113
    Jim Eager says:

    Re Knut Witberg @54: “Some even believe that the feedback is negative, so that a doubling of the CO2 in the atmosphere would cause much less than 1 C warmer earth.”

    Some also believe in fairies.

    That same low sensitivity would also apply to any other forcing, including an increase in solar insolation.

    So how, exactly, would these “some” explain known episodes of much higher temperatures in Earth’s history, desite a weaker sun?

    Oh, right, these “some” don’t do explanations, just assertions and hand-waving.

  14. 114
    Alex says:

    You’ve just raised the bar on fisking. In fact you’ve jumped right over the stand out of the stadium.

    [Response: Thanks, but technically, this isn’t a “fisk.” At least in the original usage, a “fisk” is where you have the original article in a quote level (like the quote you get when somebody responds to email) and interpolate witty and devastating remarks in between. Quite like LeMonde did with the response Courtillot got to publish as part of his “droite de reponse.” –raypierre]

  15. 115
    Eli Rabett says:

    Many thanks for Ray Pierrehumbert for this. It would be even better if he could cut it down to 500 words or so, the length needed for an op ed article in the dead tree media and we could all work to get it placed in our local papers and maybe even the national media with a reference to the longer version at the end.

    For example,

    Using only simple arithmetic and Google we find that all the world’s electricity use could be handled by solar cells covering only one ten thousandth of the Earths surface. Details and instructions for Prof. Levitt and others can be found at For the US, we would only have to cover an area x miles square, which would easily fit into Arizona.

    covers a lot of this.

  16. 116
    Sili says:

    What’s that word? Ah, yes: Oh snap!

  17. 117
    ScuzzaMan says:

    Personally, I plan to achieve zero CO2 emissions around the day I die.

    (Altho some cheapo relative will probably ruin it by burning me.)

    [Response: Don’t fret too much. The human body is only about 18% carbon by mass, which is something like 30 kilograms. That’s like the CO2 in the atmosphere above 10 square meters (in round numbers), or 0.6% of the annual fossil fuel emissions of a typical American. So, whatever your relatives do in this regard, it’s not a big factor in carbon sequestration. –raypierre]

  18. 118
    Paul says:

    Solar cells don’t collect energy 24 hours a day. Should that number be multiplied by 3, or is that accounted for in the efficiency number?

  19. 119
    The Wonderer says:

    Excellent response and I second the “good skewering” comment. I hope that before composing this letter, you took the 1/2 mile walk yourself for a face-to-face meeting and an offer of dinner. That would present the possibility of a more effective outcome, however uncertain.

  20. 120
    Hugh McLean says:

    Re your statement: “A typical coal-fired power plant only is around 33% efficient, so you would need to release 6 trillion Watts of heat to burn the coal to make our 2 trillion Watts of electricity.”

    Doesn’t 33% efficiency mean that of a total 6 trillion Watts of energy produced, 4 trillion would be waste heat and 2 trillion electricity?

    [Response: See the answer at #67. But this kind of thinking is great. It shows how having assimilated the simple principle of energy conservation you can readily spot all sorts of things that need to be checked. –raypierre]

  21. 121
    Antonio San says:

    #84 Thank you for your thoughts.

  22. 122
    Josh says:

    Hey, I just watched Levitt on the Daily Show. Jon Stewart basically called
    you and your colleagues a bunch of religious zealots.

    Could you please try to get on his show with a rebuttal?


    [Response: Yeah, hey you have any ideas of how to get on? I do play a pretty nifty bunch of jigs and reels on my accordion, but I don’t know how far that will get me. –raypierre]

  23. 123

    This is beautifully written. It’s what Jon Stewart should have done.

    [Response: Thanks, Bill. Coming from a writer of your calibre, that’s a compliment I’ll remember for a long time. –raypierre]

  24. 124
    Martin Vermeer says:

    Burgy #88, consider that the reasons people give you for holding a certain position are very often not the real reasons — if they are even aware of those. You don’t know that these three folks weren’t already holding the positions they now blame the RC comments for… few people respond well to being called ignorant, even implicitly, even appropriately (Scientists being the rare exception, as that’s what continued functioning as a scientist requires). This is something you just cannot win.

    I agree though that handle ‘mark’ is a disresource for this site — but what do you propose? ‘Censorship’? Hear the outcry?

  25. 125
    Mark says:

    “Solar cells don’t collect energy 24 hours a day. Should that number be multiplied by 3, or is that accounted for in the efficiency number?”

    The sun puts ~1kw of energy on the earth. It’s quartered because the ground doesn’t get energy 24 hours a day.

    Hence using 250W includes that feature.

  26. 126
    Mark says:

    “I agree though that handle ‘mark’ is a disresource for this site — but what do you propose? ‘Censorship’? Hear the outcry?”

    disresource, Martin?

    And if you attack the delivery not the message, that is an ad-hom.

    And how many “skeptics” claim to be scientists..?

    “…few people respond well to being called ignorant, even implicitly, even appropriately (Scientists being the rare exception, as that’s what continued functioning as a scientist requires).”

    I would suggest (as I have to Burgess and his “friend”) that if they don’t want to be called a fool, stop talking like one.

    Being a PITA means I don’t get invited to parties much, but it doesn’t make my comments wrong.

  27. 127
    Jim Galasyn says:

    Marcus, I just saw your reply. The Cquestrate people spend quite a bit of effort dealing with your questions. They envision mining the Nullarbor Plain in Australia for limestone:

    …to remove a billion tonnes of carbon from the atmosphere would require the disposal, through this process, of approximately 1.5km3 of limestone (assuming the carbon dioxide generated in the calcination of the limestone is successfully sequestered). Given that there are approximately 10,000km3 of limestone in the Nullarbor Plain and that humankind have emitted a total of 305GtC between 1750 and 2003, it would require the consumption of approximately 5% of the limestone in the Nullarbor Plain to return the concentration of carbon dioxide in the atmosphere back to pre-industrial levels.

    (305GtC seems like a low estimate — isn’t it closer to 1Tt?)

    They plan to power the operation my using “stranded” energy, in the form of solar or natural gas that’s way in the desert and uneconomical to transport. Carbon released during the calcination process could be captured or not — they propose using it for desert greenhouse agriculture.

    Would it work? I don’t know, but it’s the only geoengineering scheme that looks at all plausible or desirable to me.

  28. 128
    Joseph says:

    Why not take the suggested journey in reverse and stop by Levitt’s office?

    Perhaps he would be more receptive to your corrections in person.

    [Response: I haven’t specifically gone knocking, but I did give a talk at the Graduate School of Business (where his office is located, according to his web page) and that talk covered some aspects of geoengineering. Many of the economists, like Gary Becker, showed a good interest in and comprehension of the physical issues, but if Levitt was there at all nothing I said seems to have rubbed off on him. But maybe some lines of communication will open up now. He has a bully pulpit with the Freak Franchise, and I may be living in a fantasy world but if he can be brought around to use it to spread truth instead of confusion, the world will be better off. –raypierre]

  29. 129
    jonathan says:

    Just a thank you and a quick note. I wish I understood the science of this stuff better but then we all have our areas of interest and knowledge.

    I saw that Professor Levitt used the word “blasphemy” in his weird response. If you’re at all familiar with the internet crank/crackpot scale, you know that’s like a plus 10 because only a crank portrays his work and his views as being persecuted by some religious orthodoxy.

  30. 130
    Al Petterson says:

    Levitt’s defensiveness toward his critics – particularly those who are better informed than he is – has been really surprising. It almost does more to damage his reputation than the original error. One might have considered his reputation salvaged if he’d apologized for the erroneous emphasis in the book, instead of (as you point out) bizarrely denying that hwe wrote what he wrote.

    He misrepresented the people he interviewed, he was too lazy to do basic math, and he doesn’t seem to know what was in the book that has his name on it.

    This whole episode is a stunning indictment of Prof. Levitt, and casts a pall over the rest of the body of work that represents his career.

  31. 131
    Lisa Hirsch says:

    Fantastic and on-point takedown; funny as well. I am neither a climatologist nor an economist, but I believe in looking at the numbers any time you can.

  32. 132
    Mark says:

    “They plan to power the operation my using “stranded” energy, in the form of solar or natural gas that’s way in the desert and uneconomical to transport”

    And how is it easier to transport limestone?


  33. 133
    Dan Preston says:

    I’m not fully up on the science of radiant heat, but it’s my layman’s understanding that a large part of the heat absorbed by a supposedly black solar panel would be radiated right back into outer space without heating the atmosphere. The infrared rays emitted would have to collide with atoms in the atmosphere to warm them up – an effect that I presume would be increased to the extent that heat-trapping gases such as carbon dioxide are present.

    In contrast, the waste heat created by burning coal is in the form of hot gases (mainly carbon dioxide and some water vapor plus some sulfur dioxide) which mix directly with the gases of the atmosphere and directly contribute to warming them up. Waste heat from power plants is also commonly discharged as warmed-up water into rivers and ultimately the ocean.

    In sum, if the waste heat effect were in fact significant, it seems to me that how the heat is discharged would make a difference. I’d like to hear from someone more scientifically sophisticated, but my guess is that a given amount of radiant heat emitted by solar cells would have much less atmospheric warming effect than the same amount of waste heat generated by coal-burning plants in the form of hot gases and warmed water.

    [Response: Again, this is good thinking about physical principles, though since waste heat as a totality is a non-issue on the global scale one doesn’t need to go into this level of detail to answer the original question posed. Nonetheless, it’s interesting. You are only partly right about the fate of the sunlight absorbed by solar cells, but only partly. If you put them in a desert, which is clear, dry and cloud free most of the time, it is true that a a significant portion of the absorbed energy will be radiated directly to space (maybe a third of the infrared part of the surface energy balance, depending on how much water vapor there is in the atmosphere). But a lot of the heat transfer out of the surface will be from turbulent heat transport, and that’s maybe a half the total, depending on wind speed. That part, plus the absorbed radiant heat, works just the same way as fossil fuel burning. So, the radiant effect would be at most something like a sixth of the energy absorbed, and you’d need to offset some of that against the fact that a bit of the coal plant’s heat is also radiated away. The numbers are small, but they do provide a good opportunity to think quantitatively about surface energy budgets. (see the surface budget chapter of my book for the death-by-theoretical-physics version of how you do this stuff). –raypierre]

  34. 134
    Mark Green says:

    It was actually Dubner who stepped up to the plate to offer a response to all the criticism:

    Except for the “wrong villian” quote, which is unashamedly says he “just missed”, he is still claiming the book accurately represent the position Caldeira’s communicated to them. Completely dodges the solar cells bit and their strange logic. Do you plan to take on this too?

    [Response: Ken and I have our differences, but they are tiny compared to the difference between the plain meaning of what Ken has written and what Levitt and Dubner said in their book. Basically, Ken thinks albedo engineering may someday be needed as insurance and that it would be justified to spend about one percent of our climate research money on it. I think that “insurance” is the wrong word for it, and that even a percent would divert scarce talents from more important efforts that are more likely to pay off. Levitt thinks that albedo engineering is the preferred solution, ignores all the downside, and thinks that the existence of albedo engineering means we can just burn all the coal and fix the temperature with aerosols. He has certainly misrepresented Ken’s views, but even that is beside the point. What is more important is that he has dishonestly portrayed albedo engineering as a harmless and desirable fix, suppressing any mention of widely available research as to why it is not. Some of that research actually comes from Ken, but even if you left out what Ken has done, theres’ plenty that Levitt and Dubner should have mentioned. The problems with ocean acidification are just one of these. –raypierre]

  35. 135
    Rod B says:

    I have some problems with the accuracy of some of your assumptions and math — some pretty big. Though on reflection I would guess they all added together still fall easily within your “rough estimates suffice to make the point here” — your main point has a lot of room for internal variances. It would have been nice to see the accurate stuff for side learning purposes; but I can do that myself, I guess — not your yob. :-)

    [Response: The nice thing about laying out the arithmetic is that if anybody disagrees with any of my assumptions, they can just re-do it and find the consequences. I deliberately stuck with round numbers because I wanted to show how you could start with knowing almost nothing and arrive at the right answer. That means skipping some of the finer points. –raypierre]

  36. 136
    Rod B says:

    Stephen Pranulis (34), sidebar: what substance, in the correct concentration, is not poisonous to us humans?

  37. 137

    To mark:

    To some extent I agree with your post. My three friends probably were predisposed to deny what seems to me and you to be the obvious facts. What I might have written is this: “I persuaded some colleagues to look at this site and the nastiness and assumed moral/intellectual superiority of some posters led them to throw out the good science in the articles with the posts. Whatever — they are now quite firmly in the anti-AGW camp, and I no longer try very hard to bring the data to them that would lead them to question their position.

    Like so many many people, they have now taken a position and will not back down because it would lead them to “lose face.” And that is sad.

    My ONLY concern is that by sarcasm, “superiority” and being quick to spot trollers that more enemies are made than friends.It’s like the war in Iraq — the claim was made by some that by engaging in that war we were making enemies faster than killing them.

    The good stuff you sometimes post gets lost in the nasty packaging. That’s how I see it. Your mileage may differ.

    Burgy (not “Burges”)

  38. 138
    Mark says:

    “Like so many many people, they have now taken a position and will not back down because it would lead them to “lose face.” And that is sad.”

    And weird.

    It’s like noticing that every time you smack your head with a brick, it hurts but because someone else said it would hurt you’re damn well going to keep doing it just to prove them wrong.

    “The good stuff you sometimes post gets lost in the nasty packaging.”

    I have no problem with someone saying that when they apply it wherever needed. However what I have only ever seen is someone saying it about one side.

    Generally a denialist saying “you’re all so mean and that is why I don’t believe it any more”. Or people like yourself who ignore the worse antics of the denialosphere.

    While it’s applied lopsidedly I feel no compunction whatsoever to moderate my tone.

    PS Re: Burgess, yup, noted that just now when the “latest comment” held your name on it. Maybe I think you really look like the Penguin (from the REAL TV series, not this comic drawing carp…). Not sure if that helps, though.

  39. 139
    EL says:


    I’m happy to see you took a mathematical argument because I enjoy reading mathematically founded arguments that have good math. I think they cut through more stuff then tit for tat arguments that most people rely on.

    I, however, have one disagreement. I believe disappointment was too weak of a word; instead, I think unethical would have been a better choice.

    Take a look at this:

    I think such a portrayal is unethical.

  40. 140
    Mark says:

    PPS I only say that someone is wrong, give the reason, then tell them they are an idiot.

    If they don’t like it, they can try not appearing to be an idiot.

    And it’s very unlikely that someone will get the idiot tag until they’ve had ample time to prove it.

    As opposed to some on the denialist side who get a bye who say “you’re wrong because you’re an idiot/defrauding/religious/…”.

    Leading the statement veracity from the personal appearance rather than leading the personal appearance to the veracity of the statement is ad hominem.

  41. 141
    Eli Rabett says:

    #34 and #136, to a chemist, the dose makes the poison. I always point out that old synthetic papers include that scary description “tastes like” for some of the most toxic stuff ever made (then again, there are the papers dedicated to the technicians who made and tasted).

  42. 142
    Eric Rowland says:

    Thank you for the great article and discussion. It, and most of the comments are very approachable by non-scientists like myself.

    I noticed a comment or two regarding ‘your numbers’ and since I’ve worked in the PV industry for several years, I thought I’d work through the 16.83T kWh yearly worldwide demand relationship to the 53,333 square kilometer area required metric to see if it matches with our experience in the day-to-day world of solar panel installation.

    To keep it simple, I’ll only count the space required for the panel itself and not the space between rows required to mitigate shading issues. I’ll also assume a nearly ideal South facing installation, tilted at latitude in the Southwestern US with a standard 6″, 60 cell, 230 watt poly silicon solar panel measuring ~1.6 square meters. There are a dozen brand name examples.

    If we use NREL’s PV Watts calculator to estimate output we arrive at an average of 1.82 kWh per year for every PV watt installed. This is the average for Southeastern CA, Southern AZ, NV & NM. Energy delivered per watt installed continues to move up as technology improves, but the relationship described by PV Watts is roughly consistent with our observations over the last year.

    Using the above, I calculate that this solar panel will produce ~262 kWh per square meter, (230*1.82)/1.6. And, unless I’m about to, or already have blown the math, this panel will produce 262 million kWh per square kilometer. To satisfy world wide demand we’d need 64,237 square kilometers of solar panels. Using a high end, energy dense solar panel we can produce ~20% more energy per square meter and bring our required space directly into the area the author describes.

  43. 143
    Cremenoire says:

    This is kind of beside the point of the letter considering the randomness of the example, but I was just
    stunned by the amazing usage which deserts could be put to; solar cells “plants” I guess we could call them this way ,could power up a whole continent if implemented on a large scale within such inhospitable areas as deserts , with extremely minimal effect on GHG heat trapping and yet even lesser effect on heat waste than coal power plants.

  44. 144
    Warren Hoskins says:

    I’ve gone and posted the link to this Open Letter to my wall in Facebook, fwiw.

  45. 145
    Jason Tondro says:

    This reminded me of Carl Sagan’s priceless deconstruction of Velikovsky’s “Worlds in Collision.” Was that in “Dragons of Eden?” Anyhow, he noted by way of preface that usually scientists have a habit of just letting this sort of crank theory go unanswered, but a disproof using science is so much more educational and even, on occasion, fun. I laughed aloud and learned something at the same time. Carl would have laughed too.

  46. 146
    S. Molnar says:

    I wish belatedly to second the thought of CM way back at post #21: As much as I admire Gavin’s hard work at keeping RealClimate going (and also his recent responses, which, like that of the oceans, are growing more acidic with increasing CO2), there are few people who have raypierre’s combination of scholarship and expository skill. It’s always a joy to read him.

    [Response: Thanks, Steve. But remember that all RC posts (this one included) benefit from suggestions made by the whole bunch of RC bloggers. As for my relative absence recently, it’s only been because I’ve been making a real push to finish the never-ending climate book. It’s finally done now, except for some housekeeping chores like finishing the index, so I imagine you’ll be hearing more from me again, especially on the things I enjoy writing — the pieces on interesting new science. –raypierre]

  47. 147
    Clifton says:

    I admit that I haven’t read through all the comments, so this may already have been pointed out:

    “A typical coal-fired power plant only is around 33% efficient, so you would need to release 6 trillion Watts of heat to burn the coal to make our 2 trillion Watts of electricity.”

    4 trillion, not 6 trillion.

    Nice article, though.

    [Response: This point has been answered twice already. Look through the comments. –raypierre]

  48. 148
    Stephen Pranulis says:

    Regarding Eli’s post about dose making the poison, and old synthetic papers having comments like ” tastes like “. I worked as a chemist in a plant that manufactured precious metal cyanide salts for a number of years ( yes, that explains a lot…). While I can’t tell you much about the taste of cyanide, I can assure you that the classic bitter almond smell is only one of a multitude of odors that cyanide can manifest, depending on its concentration in air.

    Regarding Rod B’s question as to what substance in the “correct concentration” ( my God, what a telling choice of words, Rod… correct to whom… an executioner???) is not toxic to us humans. My mention of the LD50 of carbon dioxide was merely a response to the writer named “foobear” expressing the idea that carbon dioxide is not a poison. It is most definitely a poison, and not merely for its ability to displace oxygen. Saying it is not a poison is the kind of foolishness that can get someone killed (e.g. “Isn’t that ton of dry ice in a small room dangerous? Heck no, its not toxic.”). And the AGW skeptics have been propagating just that meme as a “scoring point” of late. How irresponsible is that? I think it’s somewhat irresponsible, but orders of magnitude less irresponsible than claiming that there is no evidence of anthropogenic global warming.

  49. 149
    pough says:

    I’m not sure why that is blasphemy.

    It’s not, but I must say that the purely rhetorical trick of switching from being accused of stupidity to being accused of blasphemy is as effective as it is pathetic. That is to say, it seems to be working for you, but you are pathetic for doing it. You are allowed to say whatever you like, but you are not above criticism; that is the domain of the religious.

  50. 150
    suricat says:

    Hugh McLean #120.

    I know 33% efficiency sounds low, but an EU report at states; “According to Hans-Dieter Schilling (Energie-Fakten), the average efficiency of all coal power stations in the world currently stand at around 31%, leaving a vast potential to reduce coal consumption and CO2 emissions.”, which is worse!

    If we take some ‘off the cuff’ ‘optimistic’ efficiencies through the various site plant:
    Boiler system ~80%.
    Steam turbine ~60%.
    Electricity generator ~90%.
    Substation to the grid ~95%.
    (ignoring ancillary equipment)

    Gives, 0.8 * 0,6 * 0.9 * 0.95 = 0.4104 Thus 41% Efficiency. That sounds better!

    But the story doesn’t end there. To get to the consumer’s terminals in the UK, the power has to find its way through our national grid. I understand that we currently (pardon the pun) only get out about half of what goes into the grid.

    Can we rehash that to 20.5% efficiency, or 16.5% for the given post, at the consumer’s terminals?

    Best regards, suricat.