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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. 201
    Rene says:

    200 Mark : your putative definition of ‘skeptic’ makes it the same as ‘denialist’, which just muddies the waters(a great polemic of course, withi its associations of holocaust denial). But then what word would you use for use for ‘skeptic’ as defined above?

  2. 202
    Andrew Hobbs says:

    Mike #191

    At 5W there is something wrong with your panels.

    I use a solar panel of 1.28 square metres at about 32 South and it typically produces about 160 watts for about 5 hours per day (averaged over the year) when it is sunny. About 800 WH per day. Less in winter, more in summer. It is tilted at about 30 degrees so strictly speaking it shades about 1.47 square metres of ground. This equates to about 34 W continuous or about 22.5 W per square metre. However it is a fairly ancient solar panel and I am sure more modern panels would be more efficient. I suspect the estimated 37.5 W is reasonable for sunny climates, especially nearer the equator.

  3. 203
    Radge Havers says:

    Rene, the waters are already deliberately muddied by denialists claiming to be skeptics, hence the term “climate sceptics.” Or perhaps one should always use quotes and refer to them as “skeptics.”

  4. 204
    Mark says:

    Your inerrant definition of skeptic was making a similarity that doesn’t exist, Rene.

    How many “skeptics” have said “I don’t think it’s GCRs”?

    None of those called deniers but skeptics by themselves.

  5. 205
    Mark says:

    PS I gave my definition of skeptic.

  6. 206

    Putting people into space is an old idea that also fails the energy analysis test, or what we used to call “running the numbers” on a problem. If you take this blog article as an exemplar on how to do simplified accounting of energy, then it just doesn’t work out.

    Running numbers on obsolete paradigms of space development is bound to give you idiotic results.

    The reason we go into space is to DRIVE scientific exploration and technology development on the GROUND.

    LEO is the ideal place to do this, its easily accessible radiation shielded environment is safely escaped from.

    Space colonization in this paradigm means relatively short stays by rotating crews, using cyrogenic hydrogen powered reusable launch vehicles, for continuous habitation in closed ecological life support systems.

    Once you approach those capabilities you will approach the level of scientific and technological MATURITY to be able to solve your inarguably EXTREME problems on Earth.

    The space paradigm only works in conjunction with a condensed matter and quantum physics program of exploration here on Earth. Even Obama and his staff gets it, he held a star party just before he won his Nobel Peace prize where he specifically cited the relationship between quantum physics and astrophysics. You need to get up to speed because there is no way you will pay off a public debt of tens of trillions of dollars on the path you are taking now. You have no choice – it’s required for any further progress on a planet with soon to be nine billion souls all competing for now limited resources.

    Honestly, your lack of critical thinking skills is your own worst enemy.

  7. 207
    Steve Fish says:

    Rene (#194. 2 November 2009 @ 5:30 AM):

    To continue from what Mark has said (#200), a skeptic doesn’t just say- “that can’t be.” To be a good skeptic one must present a plausible alternative explanation for a contested idea or theory (emphasis on plausible).

    Gregory (#189, 1 November 2009 @ 10:19 PM):

    I live quite well with a PV (photovoltaic) array that is about 8 feet square. How can this be?


  8. 208
    Rene says:

    I am still waiting to hear
    – a good reason to conflate ‘denialist’ and ‘skeptic’
    – a replacement for ‘skeptic’ as I defined

  9. 209
    Mark says:

    “- a good reason to conflate ‘denialist’ and ’skeptic’”

    There isn’t. Then again there isn’t any conflation between them except with the denialists.

    “- a replacement for ’skeptic’ as I defined”

    I’ve given it, Rene. See post #200.

    [Response: Please, all of you try to stick to the topic. I have a habit of closing off threads when they turn into a free-for-all brawl, and I’d hate to do that for this one since we need a place to discuss things related specifically to Superfreak. –raypierre]

  10. 210
    Mark says:

    “The space paradigm only works in conjunction with a condensed matter and quantum physics program of exploration here on Earth.”

    Whenever I hear someone use the word “paradigm” my Bullshitometer goes ding.

    Space releif from overpopulation (for this is the ONLY climate effect that the space race to LEO can address) relies on energetically cheap access to LEO.

    And what is it with the “condensed matter and quantum physics”? It means nothing. No more than “polycarbonate and semiconductor theory” would in the same place.

  11. 211
    Mark says:

    Andrew, this: “It is tilted at about 30 degrees so strictly speaking it shades about 1.47 square metres of ground”

    Is irrelevant.

    You have to compare the size of the solar array *as seen from the sun*, not how much ground is hidden, when you’re trying to work out power consumption.

    After all, the amount of *vertical* ground shaded is quite a bit less.

  12. 212
    Rene says:

    ‘denialist’ – someone who denies AGW is a problem
    ‘skeptic’ – someone who questions or doubts whether it is.

    Let’s recap.
    – I put forward these definitions, noting that many here conflate the two.
    – Mark responds that they are indeed the same, thus agreeing with the conflation.

    Given his support of this conflation, I asked Mark for a replacement for ‘skeptic’ as defined above. He has not done so, despite his repeated claims to the contrary.

  13. 213
    Hank Roberts says:

    Rene, there’s a third category, try “disrupters” — who will take any climate conversation off the rails; one good way is starting or feeding any argument about definitions. Leads to excessive recreational typing. E.g.

  14. 214

    Hank (174)
    “…don’t see it there and only see it here…”
    Use of agressive language is happening on both sides. I think the side that diminishes abusive language first may have the best chance of engaging newcomers to this debate to their side. For the public, it’s not just about the facts. It’s about the packaging just as well (or even more so).

    As I wrote to Mark over at Deltoid: There’s more chance that they listen to me when I’m nice than when I’m nasty. Read or look at some Greg Craven for a great example on how to communicate constructively.

  15. 215
    Radge Havers says:

    Disrupters– now that I think about it, that’s a pretty good term for Levitt and the general pandering to middle brow resentments and yearnings for grandiosity. The result: belligerent sophistry, the last refuge of status quo extremists.

    I think this article should be e-mailed to congress critters with a short cover on the state of political dialogue in this country.

  16. 216
    KevinM says:

    “Donald, the problem is getting that small black square in the public eye.”

    You’re joking, right? Looks about the size of Delaware.
    Now add a battery the size of Rhode Island and cables and towers from Saudi Arabia to Kansas.

    This is the same kind of math that puts all of humanity in a 1 mile by one mile cube. It can be done but it is senseless.

    How about putting the 1,000 Nuclear reactors that produce the same amount of electricity with no carbon emission on the same scale. They would be invisible.

  17. 217
    KevinM says:


    I’d also add an unsceptical but not scared category. What is bad for Arizona might be great for Manitoba.
    If I were Swedish I’d be subsidizing Chinese Coal plants.

    [Response: This is a pretty short-sighted comment. It is an interesting historical note that Arrhenius thought of global warming as a good thing for Swedish agriculture, and a possible means of restoring some of Sweden’s former position as a world power. However, I have spent a great deal of time in Sweden, and the Swedes haven’t seen the issue this way for a long time. For one thing, they actually like their country the way it is, for the most part. They don’t want to see the wildlife and sweeping tundra landscapes disappear. For another, there are various aspects of global warming that impose serious problems in Sweden. Loss of cold winters increases survival of insect pests like Oporinia,and it increases the mosquito and warble fly season up North, which is a threat to herding. Sweden has a huge investment in hydropower, and shifts in rainfall patterns threaten a lot of that. On top of that Swedes and their government tend to have a lot of compassion for the suffering of the rest of the world. Thus, it’s no surprise that Sweden has taken quite strong efforts toward mitigating emissions. On top of that, Swedish scientists have played a lead role in advancing the scientific underpinnings of the need for action. Think of Bert Bolin’s pioneering role in ocean carbon uptake, and in the first IPCC report. –raypierre]

  18. 218
    Rod B says:

    Stephen Pranulis (148), CO2 is nowhere near poisonous in the concentrations AGW is fussing about; so throwing the pejorative “poison” in the AGW debate is disingenuous. You do make a good point, however — that CO2 is much more poisonous and dangerous than the common man considers.

  19. 219
    SecularAnimist says:

    In the context of discussing anthropogenic global warming, a “skeptic” is someone who unquestioningly believes everything that Rush Limbaugh has to say about the subject, and is also certain that hundreds of climate scientists who have studied the issue diligently for decades are either so stupid and oblivious that they have missed the simple, obvious reasons why they are all wrong about it, and/or are possessed of such evil, powerful Machiavellian intelligence that they have successfully engaged in perpetrating a massive hoax on humanity in order to advance their “liberal” agenda.

    [Response: OK, enough of this discussion of skeptics and deniers. I’m going to delete any further comments I catch on that subject. –raypierre]

  20. 220
    Steve Fish says:

    Following Raypierre,s inline admonition (#209. 2 November 2009 @ 10:09 AM), Hank Roberts’ comment (#213, November 2009 @ 11:23 AM) reminds me of his previous discussions of how serious online conversation is easily disrupted by outrageous off topic posts.


  21. 221
    Rod B says:

    George B (157), World energy consumption per capita of 150 kw-hrs/day seems way out of bounds; that’s about 4500 kw-hr/month per capita which is near twice the per household use in my environs, and (I’m guessing here) this is likely 10x or so the world average. Would a few aluminum and steel plants and the like drive up per capita use that much?

  22. 222
    Brian Brademeyer says:

    #221 Rod B,

    Are you not confusing electrical energy with all energy?

  23. 223
    catman306 says:

    File this next to Easter Island.

    Logging caused ‘Nazca’ collapse. It was more than an el nino flood that destroyed this South American culture.

  24. 224
    Patrick 027 says:

    I’m just stopping by without have read many comments here, but something that may not have been considered:

    Assuming zero albedo to the utilized solar radiation* (see below), the local effective albedo is the efficiency of conversion to electricity, the electricity will then have the same heating effect as any other electricity where it is used or lost. Of course, in one way or another, this point has already been made.

    But consider then what happens if efficiency rises above the albedo of the surface being replaced. There would then be a local cooling effect (except for any changes in evapotranspiration), and the heating in electricity consumption would be more than the total effect.

    Now consider:

    Flat panels which are tilted to get the most insolation would benifit by having the surface (and back of the next panel) having much diffuse reflection, which would also reflect some more solar radiation back up.

    * Geometric concentrators only concentrate direct beam solar radiation. Thus, parabolic troughs, parabolic dishes, and mirror arrays for central recievers, can have an albedo approaching the ratio of incident diffuse solar radiation to total insolation (concentrator systems being at their best when clear skies are common, I’m curious what that ratio tends to be under such conditions). And then, the conversion efficiency of the concentrated radiation tends to be higher in these systems (in the case of CPV can justify higher costs per unit area of the PV device).

  25. 225
    Rod B says:

    raypierre (219), thanks. Saves me a lot of impossible effort…

  26. 226
    Rod B says:

    Brian (222), hmmmmm. Maybe…

  27. 227
    Mark says:

    Rod B: “Stephen Pranulis (148), CO2 is nowhere near poisonous in the concentrations AGW is fussing about; ”

    Go back and read, Rod.

    1) The poisonous concentrations ARE relevant to someone who states CATEGORICALLY that CO2 isn’t poisonous

    2) The toxicology of CO2 isn’t the issue with AGW and you know it, it’s the heat entrapment.

  28. 228
    Mark says:

    “This is the same kind of math that puts all of humanity in a 1 mile by one mile cube. It can be done but it is senseless.”

    The human capacity in 1mile cube is senseless, but the small square IS doable.

    The UK are investigating Jordan (I think) as a power generator for UK electricity:

    1) UK companies rent the land,
    2) build and maintain the solar panels
    3) sell the electric to the UK
    4) Profit!!!

    Remember: that little square is all that’s needed to keep our (well, YOUR, if your USian) profligate lifestyle unchanged by solar alone.

    And please prove the battery size will be needed.

  29. 229
    Mark says:

    “As I wrote to Mark over at Deltoid: There’s more chance that they listen to me when I’m nice than when I’m nasty.”

    And will Roy Spencer listen to you explain how evolution by natural selection is true and his book is wrong just because you’re nice?

    You seem to be labouring under the impression that the chance they’ll listen to you is greater than 0%.

    But I guess you can always blame me if you’re not being listened to, can’t you.

  30. 230
    Mark says:

    Rene, please read post 200.

    Your demand is answered there.

  31. 231
    Patrick 027 says:

    Re 189 gregory –

    Energy payback times are short enough that even if fossil fuels were continually used to support solar power and related infrastructure, it would still be a huge, huge, huge improvement in terms of climate-changing emissions per unit energy. Of course, as solar or other clean energy takes over, more of that would be used in the support of its own infrastructure. By the way, fossil fuel energy is today used in part to support it’s own supply – this isn’t unique to the renewables (or nuclear, etc.).

    Yes, of course, other resources besides energy are used. But better to only have that problem than have the climate problem as well, and also, the mineral resource constraints are not really a problem unless you restrict yourself to a subset of the technology. Land use is not entirely inconsequential but it should be manageable. Anyway, why assume that any solution must come along with continued exponential growth?

  32. 232
    Phil Scadden says:

    Rod B. Average American ENERGY (not just electricity) is 250kWh/p/d. Average
    European or Japanese is more like 125 kWh/p/d

  33. 233

    Mark (229),
    If you’re so sure the chance they listen to you is absolute zero, then why do you bother? Perhaps it’s better indeed if you don’t bother.

  34. 234
    Julia Isaak says:

    #207 Steve Fish : “To be a good skeptic one must present a plausible alternative explanation for a contested idea or theory (emphasis on plausible).”

    No, one need only find fault with the presented theory.

    [Response: Not if you want it to be replaced with something else. All theories are approximate in some sense – and the current conventional wisdom is usually the approximation that best fits the multitude of observations. But since it isn’t ever a perfect fit, and the approximations are, well, approximate, it is certainly not sufficient to repeat these two facts in order to dislodge the existing paradigm. – gavin]

  35. 235
    Julia Isaak says:

    To find fault with a given theory does not require you to first have a better one. The best available theory may still be hopeless, so if the truth is we just don’t know, or have only a poor grasp, we should just say so.

    [Response: But where you have a theory that does work for a wide area of the observations, it is clearly a step backwards to reject it in favour of throwing up one’s hands up in despair. All aspects of any theory can of course be challenged and that generally prompts more careful workings out of those issues if there is anything valid or constructive in the challenge. But simply saying it’s approximate! or it’s not perfect! is not going to advance anything (since this is already understood). – gavin]

  36. 236
    KevinM says:


    “The human capacity in 1mile cube is senseless, but the small square IS doable.”

    I think I spoke unclearly. I meant literally fitting all of humanity into a cubic mile.

    Give each person 2 feet by 5 feet by 1 foot on average (accounting for most people being skinnier than me) and you get 10 sqft per human. One cubic mile is 5280ft x 5280ft x 5280ft = 147 billion cubic feet.

    Thus every living human on earth could be packed into a one mile cube. We would fit into just about any small town in the USA.

    This is a demonstration of how back of the envelope calculations can go wrong.

  37. 237
    KevinM says:

    “To be a good skeptic one must present a plausible alternative explanation for a contested idea or theory (emphasis on plausible).”

    I’de start with: Both sides agree that the world has several times been covered with ice, at least once near the equator, and subsequently melted back to something like its current state.

    I believe that is an immensely more drastic change than anything we’ve seen during the instrumentation period, which contains the only scientific data I trust.

  38. 238
    Mark says:

    “If you’re so sure the chance they listen to you is absolute zero, then why do you bother?”

    I think the chance they listen to YOU is absolute zero.

    People have tried education. I do that too if someone asks a good question.

    People have tried satire. I do that too if someone asks a bad question.

    Neither have worked.

    If anything the sounds of a “loud consensus” (which doesn’t require a consensus of a large number of people, they just have to be loud about it) increasing shows it’s having no effect.

    So I try scorn.

    You don’t have to.

    Gavin, Ray and others do on occasion.

    But the idea of scorn is to use it where deserved.

    It’s not to get them to listen to the arguments, it’s go get them to think before they open their big fat gob and spout the same old fishheads over and over again.

    It’s not like they even have a theory themselves.

    On the BBC Climate blog one poster has listed 82 differing claims of skeptics.

    In doing so he’s not had anyone saying which ones are wrong (several are incompatible with each other). Instead he’s had

    “Why are you listing your silly arguments?” he isn’t, he’s listing those of others

    “All you’ve done is raise good reasons why AGW is wrong” but they can’t ALL be right, so which are right and which wrong?

    “It’s silly and you’re silly and it’s all silly.” Thanks

    “Why are you saying they’re my arguments” when several have been the argument against AGW by the interlocutor asking this question

    They have no goal except to throw down AGW.

    But if we treat these farcical idiots to the contempt they so clearly and emphatically deserve, maybe they’ll stop yakking in shame.

    If they don’t, why would someone consider such ludicrous and easily countered arguments (with scorn!) irrelevant because you just want to concentrate on the “why did you have to be so *mean*!”?

    Take a look at this open letter.

    It is scorn personified.

    But he’s got more time and space (and pictures) where I have to get it done in a few short paragraphs.

    And we’ve had Steve Levitt come on and wail “why are you all so mean!” at us.

    They act contemptibly, I will treat them with contempt.

    NOTE: I have agreed with Rod B on several occasions. Jim has sometimes given good advice. Both are definitely “skeptics” (i.e. deniers) because they haven’t learned no matter what they have been told.

    Likewise Hank has pulled a few whoppers out and Ray likewise.

    I call them on it despite being behind AGW science.

    Hank et al get a modicum of scorn (a scornette, maybe) when they’re being dumb because they haven’t built up the level of unthinking that Rod B has managed to hoard so eloquently here many times before. The actions of some of the bigger denialist names are contemptuous and they earn contempt. But if one were to say something sensible I would agree not because I’m being even handed but because they say something sensible. Past performance will judge whether I start off thinking “lame” or not, but when I’ve read, I forget the source and consider the words.

    Try it.

  39. 239
    Patrick 027 says:

    Re KevinM – “This is a demonstration of how back of the envelope calculations can go wrong.”

    Yes, if the point was to justify putting all people into a cubic mile.

    No, if the point was to use volume * density to calculate the total mass of all people (except you have to account for packing efficiency), and/or come up with a visualization for the total volume of people compared to … say, an ice berg or a mountain…

    Saying that all solar power needs an area x of panels equal to a square z x z doesn’t require actually putting all the panels together in a continuous stretch of space. Total area is total area.

  40. 240
    Julia Isaak says:

    Your reluctance to discuss exaggeration and bias wrt mainstream AGW is duly noted.

    And the general complaint with AGW is not thats it’s merely approximate. There are gaping problems – airbrushing out the MWP, failure to account for the two long periods of cooling in the last century despite CO2 increases, the need to treat of natural forces as random. All it really has is the period from ~1980 ending in the nineties, just prior to the plateau of the last decade or so it also fails to account for.

    [Response: There I was thinking that we could have a conversation about generalities without irrational views about climate science coming to the fore. As I recall we were talking about the role of critics to a dominant paradigm and the task they have to dislodge it. Let me assure you that this task is not achieved by people making up accusations of supposed failings and setting up strawman fallacies to knock down. The idea that the argument that the global mean temperature is not a perfectly correlated to CO2 amounts is any kind of challenge to mainstream climate science is simple nonsense (since no-one believes that should be the case). You will have to do much better (and you will have to do it elsewhere since all of this is OT). – gavin]

  41. 241
    Chuck Doswell says:

    Bravo, Prof. Pierrehumbert! The deniers seem disinclined to let science-based facts clutter up their political agenda. Yours is a voice of delightful scientific reasoning in a cacaphony of nonsense. The power of simple calculation is a thing of great beauty.

  42. 242
    Patrick 027 says:

    Re 234,235 Julia Isaak –

    To put it another way, increasing levels of understanding often come by way of successive reductions of error.

    For example, Newtonian mechanics still works quite fine for many purposes; relativity is required for various spatial-temporal and mass scales wherein the Newtonian mechanics errors are large.

    The Earth can be approximated as a sphere of radius of about 6371 km. Okay, if I said 6400 km, how wrong would that be? Would that error disprove the shape of the Earth – would we now think the Earth is flat?

    But of course, the Earth isn’t a sphere. First, you have to know what I meant by Earth – in this context I am refering to the shape enveloped by the solid/liquid surface, not the tropopause, not the magnetic field lines. Second, the Earth is really an oblate spheroid – wider at the equator than at the poles. Except not quite. And so on. Yet, for many purposes it is just fine to use a perfect sphere to approximate the shape of the Earth (as defined by the continuous surface bounding the solid/liquid portions).

    A complex system as the atmosphere (and ocean) may be studied in some ways by considering the largest factors and then working up to the details. For example, for large-scale motions not too close to the surface or too close to the equator and not with too much speed relative to flow curvature, the two largest forces acting horizontally on air are the pressure gradient force and the coriolis effect, and when acceleration itself is small, as it general is in large-scale motions, equations of motion can be solved for a velocity field that is geostrophic. Geostrophic winds are often a good approximation for reality in much of the atmosphere. With that, one can then consider the effects of imbalances in those two largest forces, or additional forces, that cause acceleration. To a first approximation, products of relatively small values can be set aside, as is done when using a linear approximation. Key aspects of baroclinic instability can be understood in this way, without even considering any diabatic (radiant and latent heating/cooling) or viscous (friction, turbulent momentum mixing) or mesoscale (fronts, narrow jets, thunderstorms) processes. But once some of the basics are understood, the additional effects can be added in. And so on.

    Climate modeling is approximate because of the grid-scale limitations. So, what kind of error do you expect to find when the computers allow grid-scales to shrink by a factor x? Would it be anything that significantly alters the seriousness of the issure of global warming? What does the paleoclimatic evidence suggest?

  43. 243
    Hank Smith says:

    Re: 197. Its clear you know nothing about technology. As if technology didn’t exist in the 19th century, what a stupid notion. Technology has existed since man first used fire. You’re electrical grid runs on the same fuel as the steam engines of the 19th and 20th and 21st centuries; coal, oil. But it uses a great deal more of these nonrenewable resources then steam engines do, to get the same amount of work. Just because human labor isn’t being utilized doesn’t mean less work (energy) is being used. An electrical grid isn’t energy at all, its a transformer of energy, that’s all any technology is. Fire burns the carbon stored in trees, etc. Saying solar converters can run on an electrical grid is just lapsed reasoning. Solar converters are made through the exploitation of highly concentrated nonrenewable energy, i.e., coal and oil. As is the electrical grid.

  44. 244
    Julia Isaak says:

    #242 Patrick
    I quite accept the notions that
    * the climate system is highly complex
    * approximations of this are the way to approach it.
    My reservations relate to the following comments to Gavin.

    #240 Gavin
    I set up no strawmen; the simple fact is there is an extremely poor correlation between AGW and widely accepted measurement data. This I suggest is reason enough to be skeptical, certainly of the claim that the science is ‘settled’.

    [Response: Sorry, but you are not being clear. What measure of ‘AGW’ do you think should correlate with what? Do you mean CO2 concentrations with global temperature? the radiative forcing of CO2? the radiative forcing of all the factors changing atmospheric composition? And where is there a prediction that these things should be perfectly correlated? How can mainstream theory be faulted for not matching a prediction it never made? And not credited for the predictions it did make? And when did I ever say that ‘the science is settled’? Every statement you have made is to criticise a strawman argument that we have never made. How is that useful? If I might offer some advice, stop reading whatever it is you are reading, and start off with the IPCC FAQ. Then come back and discuss. – gavin]

  45. 245
    Tony Rogers says:

    Re Mark #238:

    I think if your objective is to stop any skeptics posting here then you will probably be successful with your approach. I’m surprised that you or those who set up RC would want it to work like that.

    If the objective is to convince and persuade then I can tell you that your approach doesn’t work.

  46. 246
    Donald Oats says:

    Re Thomas Lee Elifritz #206:

    Perhaps I misunderstood your original point in #186. I read your statements – the pertinent extract is below – as implying a move of a lot of people into space to live. The bit about “Develop low Earth orbit or die.” was what set me on that line of thought.

    The quote from Thomas Lee Elifritz #186:
    “Nine billion people all demanding and striving for a quality of life of 350 million in America alone? Give me a break. Develop low Earth orbit or die. That’s your immediate choice. Nobody can predict how this will play out, but unless you come up with multiple Manhattan style projects in both condensed matter and quantum physics (not high energy or nuclear physics or fusion crap – real everyday physics from absolute zero to 1100 K or so) AND low cost earth to low Earth orbit transportation and LEO development (RLVs, closed ecological life support systems, Earth observation and observatories) then you simply don’t have a chance here.”

    From #206, you state something that I agree with:
    “The reason we go into space is to DRIVE scientific exploration and technology development on the GROUND.”

    However, I don’t understand why it is necessary for you to then impugn my critical thinking skills :-(, again from #206:
    “Honestly, your lack of critical thinking skills is your own worst enemy.”

    Please, let’s keep to a discussion with clarifications where needed, I wasn’t intending any offence with my original post.

  47. 247
    Lynn Vincentnathan says:

    I think Levitt et al. should see the Steve Martin movie, THE JERK. There’s another pertinent source, the book WHY THINGS BITE BACK re unintended negative consequences of our “solutions” to problems.

    Better yet, read what Rappaport (an ecological anthropologist) has to say about economics. Here’s what I wrote on another RC geoengineering topic last August, starting with an excerpt from my “Food Rights and Climate Change” paper:

    I find the position economics plays in Western thought to be inflated, even usurpatory, obscuring people’s awareness of their dependence on the environment or the ecosystem, and this is due to people conflating the environmental/subsistence dimension [of the human condition] with the economic (social), subsuming the environmental/subsistence into the economic as “resources,” valueless unless processed and (in capitalistic society) exchanged for money….economics cannot ultimately solve or rectify environmental harms…[E]king out a living from the environment…is considered in anthropology more within the realm of “subsistence activities” or ecological anthropology; this is distinct from economics, in that it has to do with the human-nature relationship, involving biological and other material exchanges between the nonhuman material world and humans, while economics, part of the social dimension, more narrowly involves human interrelationships and interactions — tenure and ownership rules, the division of labor and production of goods involving materials extracted from the environment (an environment which is held constant or deleted from the equations), and the exchange of goods and services…

    One way to understand the distinction between the environmental/subsistence and economic dimenions is that both humans and non-human animals engage in subsistence activities in the environment, but only humans engage in economic activities. As environmental anthropologist Roy Rappaport (1993) states the biological-ecological systems are fundamental, the economy is contingent and instrumental.

    From Roy Rappaport’s “Anthropology of Trouble” (1993, American Anthropologist 95(2):295-303):

    The world upon which the monetary metric is imposed is not as simple as the metric itself. Plants, animals, and societies are complex beyond full human comprehension. To remain healthy, each requires a great variety of distinct materials, generally derived from a variety of sources….Monetization, however, forces the great range of unique and distinct materials and processes that together sustain or even constitute life into an arbitrary and specious equivalence. Phenomena that relate to each other essentially in terms of their qualitative distinctiveness are represented and understood in terms of a logic that reduces all qualitative distinctions to mere quantitative differences, a logic that, as it were, attempts to “bottom line” the world. This logic is especially destructive of ecological systems.

    So that’s my view of economics — often useful as a facilitator in a limited sphere of activities, but totally blown out of proportion in the Western imaginaire.

    The other issue from a more purely economic perspective is why should we spend money on big geoengineering projects that do not save us or make us money the way nearly every other solution to GW does, such as energy/resource efficiency/conservation, alt energy, and biochar (the only carbon negative solution – that saves/makes money and enhances agricultural productivity — see ).

    Or is that what “freak” means in freakonomics — totally uneconomical and crazy, not to mention harmful to the environment and our livelihoods.

  48. 248
    Donald Oats says:

    Re KevinM, #216.

    In my original post #20, I wasn’t joking.

    My original post #20 stated:
    “For people without much scientific background, I think they would especially appreciate the picture of the world with the little black rectangle on it – it makes the whole argument you are putting forward resonate, and hopefully sways the still skeptical to at least follow your argument through to the end.”

    I was simply stating that the little black rectangle on the globe gives some indication of the order of magnitude of the area consumed by the solar panels themselves, and since the heat/albedo impact is what Ray-Pierre was analysing in his article, I see no problem with that.

    As you point out KevinM #216, distribution networks and things are required. However, an awful lot of the distribution network is there right now. Ray-Pierre is not suggesting that the global solar power generation is to be situated in the one place – it’s just convenient to show it as a single area on a map for purposes of comparison. Secondly, for those people who install solar at home, or at the office, the distribution network is extremely short, and the area consumed by the solar panels was already consumed as a roof on a house. Batteries or some equivalent storage mechanism are something that should be added to the resource footprint; I agree with you on that.

    I do not see the maths as being on par with your example of those who “demonstrate” that humanity could fit in a one mile cube; indeed on other blog sites I have tried to demonstrate failures of this kind of calculation, especially concerning land area required per person supported, but to no avail. Some people just like the idea of living cheek to jowl, I guess :-d

  49. 249
    EL says:

    OT but interesting…

    I found the following article by Charles Krauthammer:

    I think this article is interesting, in particular, the following quote:

    “Only Monday, a British parliamentary committee proposed that every citizen be required to carry a carbon card that must be presented, under penalty of law, when buying gasoline, taking an airplane or using electricity. The card contains your yearly carbon ration to be drawn down with every purchase, every trip, every swipe. ”

    I think the above quote is interesting because it illustrates that some people are concerned about the government perspective of global warming. In a basic nutshell, ideologies are likely an important factor in the global warming debate; as a result, the ideologies need to be addressed in order to make progress.

  50. 250
    Mark Baker says:

    So if the world needs 53,333 square km of solar panels and it costs $150 million dollars to build 180 acres of solar panels, does this mean your project costs $11 trillion dollars?

    Largest solar panel plant in US rises in Fla.

    180 acres for 25 megawatts and $150 million.

    180 acres equals 0.728 sq kn
    53,333 / 0.728 * $150 million = $11 trillion

    [Response: Imagine yourself back in 1880 trying to figure out the cost of replacing all the world’s horses with internal combustion engines. -raypierre]