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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. 251
    Patrick 027 says:

    Re 246 Lynn Vincentnathan –

    Okay, good points, and maybe a lot of people have this problem. But a truly good economist should be able to avoid the pitfalls of economic analysis.

    We ultimately have to bottomline things to make decisions when we compare apples to oranges. If we are choosing some combination to have of apples and oranges – for example, if the production possibilities curve is, when graphed in value-proportional coordinates, convex everywhere (decreasing returns), then we will want to choose the point on the curve where the marginal value of x apples equals the marginal value of y oranges when the physical constraints allow x apples to be exchanged for y oranges. If the production possibilities curve has concave portions (increasing returns) than there will be multiple optimal, and evolution of the choice by small changes and trial and error could easily miss the best optimum.

    Of course, such a two dimensional production possibilities curve (PPC) is just a slice through a multidimensional curve; the whole slice can be changed by adjusting some other thing (number of bananas), and then, there may be different such PPCs at different times which are slices of a PPC that encompasses all potential decision pathways (with later being contingent on earlier, but the value of an earlier decisions being in part contingent on the value of subsequent decisions made possible by that earler decision).

    But the point is, we ultimately have to equat apples to oranges in some way, by their ‘value’, in order to make decisions.

    On an individual level, that value is not entirely money-based, at least not in an obvious way, for example, when I actually have fruit on hand and I’m deciding whether to have an apple or an orange, or when I decide to go for a walk verses watch TV verses have a conversation. But the economic value of something not explicitly given such value is implicit in the trade-offs that people make (though any given decision might only imply an inequality, where we know something is valued more or less than something else, and also, the scarcity of decision making resources makes it rational to not always be perfectly rational…). So long as it is realized that the same item will have different economic values to different people at different times and will be contingent on the presence or absence of other items (more vitamin C isn’t worth much to keep you healthy if you already have enough vitamin C or if you don’t have air). Another way to look at it is to consider that all economic value exists because of the combination of aesthetic value and scarcity.

    As for natural resources, there is value in the state of nature, via ecosystem services, tangible and aesthetic. Thus natural resources can be utilized without actually being used-up.

    Which of course, you know. My point is that it isn’t necessary for an economical analysis to ignore it.

    Of course, there is morality – it is good, all other things being equal, for a person to have what s/he wants, and besides that, economic wealth can confer an ability to enhance the moral value of available choices (this isn’t to say that rich people can be better people, not at all – what it means is that the same persons’s good intentions can have magnified effect depending on the person’s resources).

    But even making a moral decision will very often require an apples to oranges comparison. Even with what we do with the environment. If there is something we should do, it is because of the greater moral value in that path than in the alternative. What we should do is maximize (at least, given decision-making resource scarcity, maximize in a probabilistic sense) the moral value, which in some ways will involve maximizing economic value, though with potential qualification.

    So if there is something we should be doing, or if path A is better than path B, there is bottom-lining of some form or another.

    Animals and plants also ‘make decisions’ in effect – the rational decision making process might be trial and error honing of instincts or habits or rules of thumb in genetic evolution or in cultural evolution or in the learning processes of a single individual – nonetheless there is an implied bottom-lining for the costs and benifits for the reproductive success of a gene or the pleasure verses pain of a sentient organism, etc (weighing attempting to mate now verses go eat now and mate later, etc.).

  2. 252
    KevinM says:


    Yeah, you’re right. I actually do like the idea of solar power for water heating and suplementing grid power for appliances. At least I think it makes a lot more sense than wind farms.

    But you have to admit thats a huge area of solar panels.

    And nobody took the bait on a comparison to nuclear. The physical area occupied by nuclear plants required to generate the same electricty really would fit in ane city. It would be less than a pixel in the diagram.

    I’m not sure why hard core environmentalists continue to hate nuclear.

  3. 253

    150 suricat,

    Your guessing about the boiler system and the steam turbine sounds like you are not aware of the effects of the Second Law of Thermodynamics, and a lot of other problems. The amount of heat discharged by our system of central power plants is indeed enormous. Most fossil fuel plants run close to 30% efficiency with combined cycle natural gas plants getting close to 50%. In some years the combined cycle systems bring the average for USA natural gas efficiency close to 40% efficiency. Old natural gas systems and relatively inefficient “peaking” natural gas plants work the other way. Coal varies also but the USA average is about 31%. I worked this out for EIA data where the efficiency I calculated was for electric energy produced versus fossil fuels burned. (See the analysis page at for details.)

    Probably the electric generators are a lot more efficient than you guess and the total loss for transmission averges 7% to 8% (92% to 93% efficient ) As far as I was able to find, the data reported to the EIA only allows us to know the amount of fuel burned based on the amount of CO2 produced and the amount of electricity produced at the power plants.

  4. 254
  5. 255
    Mark Baker says:


    I actually think that $11 trillion is not too large when you divide it over 10-20 years and ~20-30 major countries. Somewhere on the web I saw the interstate highway system cost $500 billion in today’s dollars.


  6. 256
    George Blahusiak says:

    For those who follow such matters, at the Johan… conference it was said that fully 1/4 of the world’s population has no access to electicity at all. Zip. Zero. Zilch. Nada. Add that factor into the calculation of solar collector area. By the way, I calculated energy growth over the next 40 years. I see the Professor used 2005 and it was only estimated at that. I should have used 45 years. Add that to the calculation.

    On another matter, I despair of people, even highly qualified scientists, who quote the energy falling on the Earth in 1 hour, day, or whatever, saying it is enough to supply the world’s energy needs for a year, or whatever. The fact is that fully 98 percent of the energy falling on the Earth, if not more, is already being used, either to evaporate water from the oceans or grow crops, or give us a nice tan on the beaches, or to light our cities, or whatever.

    Those who count only domestic energy/electricity consumption and claim that once they have solved that the there won’t be problem are worse.

    Those who claim that using low energy lights will help haven’t done the numbers. Lighting consumes, on avearge, only 7 percent of dometic electricity consumption, and domestic elctricity consumption is only 7 percent of total average energy consumption. Ergo, even if every low energy light was replaced it will save only 0.5% of total energy consumption, an amount that will be exceeded by world energy growth within 3 months (at 2.2% p.a. growth).

    By the way, my domestic energy consumption is only 2.5 pecent of average total energy consumption. Please don’t ask me to cut back or else I will be living in a tent.

  7. 257
    Andrew Hobbs says:

    Mark #211
    With regard to tilted solar panels you suggest 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.”

    (I presume you meant power production).

    This depends upon where your interests lie. If you are interested in the area of the solar panels, ie the area of panels required for a specific output, then that is true. If however you are interested in the area of ground required to produce a specific amount of power then it isn’t necessarily true. At the equator it is. But not at higher latitudes. At higher latitudes you can tilt the panels to get maximum power per area of panel. This will shade the area behind the panel which means the area of solar panels will be smaller than the area of the solar panel farm. Alternatively you lay all the panels flat, using 100% of the area but at a cost in terms of requiring greater solar panel area for the same power output.

  8. 258
    Hank Roberts says:

    Encouraging words:

    Encouraging, funny, instructive video on light bulb energy:

  9. 259
    Paul L says:

    KevinM, #252. There’s a good economic reason why nuclear power couldn’t be built on that scale: uranium ore. It’s already predicted that uranium is going to shoot up in price over the next decade as new nuclear power plants are built in several countries. The uranium-exporting countries aren’t likely to be able to increase extraction enough to cope with demand, not for a decade at least.

    I don’t know much about the other options but it seems to me that the long-term economic benefit of setting up electricity generation which *doesn’t need fuel*, will outweigh the current cost within a few decades. Those countries that bite the bullet now will be at a big advantage 20-30 years down the line.

  10. 260
    Paul L says:

    One more thing, I don’t think anyone has posted a link to this article in today’s/yesterday’s Guardian:

    Solar power from Sahara a step closer

    “A $400bn (£240bn) plan to provide Europe with solar power from the Sahara moved a step closer to reality today with the formation of a consortium of 12 companies to carry out the work.

    The Desertec Industrial Initiative (DII) aims to provide 15% of Europe’s electricity by 2050 or earlier via power lines stretching across the desert and Mediterranean sea.

    The German-led consortium was brought together by Munich Re, the world’s biggest reinsurer, and consists of some of country’s biggest engineering and power companies, including Siemens, E.ON, ABB and Deutsche Bank.

    It now believes the DII can deliver solar power to Europe as early as 2015…”

    So it seems like this article has been giving people ideas!

    Just one other thing, someone said that the UK government plans to buy solar energy from Jordan. I can’t see how – they’d need to build a helluva a lot of batteries to transport it. Even the proposed Sahara deal might not benefit Britain, we’d need high-power lines running to the continent. But to be honest, wind and tidal power make more sense for us anyway.

  11. 261
    Lynn Vincentnathan says:

    #251, Patrick, I only took a few courses in economics, but I did learn about the “production possibilities curve or frontier,” and my thinking is that first of all we have to get out there onto the curve. It seems to me (see and ) that we are way way within the pp curve. That is, given our current knowledge and off-the shelf technology, we are terribly terribly inefficient.

    I’m thinking first of all we have to do all the low-hanging fruit stuff (that saves money or doesn’t cost), which should keep us busy for 10 or more years down to an 80% reduction in GHG emissions (and why we haven’t already done this over the past 20 years is a total absurd mystery). Within 10 years biochar could be readily available on the market for city yard waste, carrizo cane control along the Rio Grande Valley, and each farm could have these money-making or saving, productivity enhancing, carbon draw down biochar pyrolisis units. By that time, the expensive geoengineering schemes will seem even more crazy than ever.

    It seems to me the only thing lacking in this picture is “rational, economic man” — upon which the whole of economic theory is based, like a house built on illusory sand.

  12. 262
    tharanga says:

    Why are people taking the illustration here so literally? The point was to show that waste heat can’t possibly be a significant issue with solar cells – even in the extreme case where all the world’s current electricity needs came from PV solar cells.

    That hypothetical illustration does not mean raypierre actually thinks all the world’s electricity should come from solar cells anytime soon, or that those cells should be clustered in Saudi Arabia, or that he thinks electricity consumption will not change over time. Perhaps he does think these things; I don’t know, but this blog post alone would not tell you that. The post was just proving a physical point, not making a policy recommendation.

    Finally, while we’re talking solar, don’t sleep on concentrated solar. If solar ends up playing a bigger role, I would not be surprised if the scale comes from thermal solar, not photovoltaics.

  13. 263
    Patrick 027 says:

    256 George Blahusiak

    – “Please don’t ask me to cut back or else I will be living in a tent.”

    Better to live well and efficiently then simply give stuff up, but at any rate, good for you. You shouldn’t have to cut back the same as others who are using far more. (This is part of the problem with people suggesting that China and India should reduce emissions or else it’s not fair – or maybe that’s not what they meant? I think a lot of people really have no idea what the word ‘fair’ is supposed to actually mean.)

    Lighting might be small, okay. But it’s part. Every end use is only one part; increasing the efficiency whereever it can be done is good. After CFLs will come LEDs. But passive solar lighting (and heating) should not be forgotten. PS in air conditioning season, more efficiency within buildings reduces energy use for cooling. (If we were to start replacing old inefficient appliances while they’re still useful, they might be best resold in Canada, Scandinavia, and Russia – well, maybe.)

    However, ‘I have a problem’ with this:

    “The fact is that fully 98 percent of the energy falling on the Earth, if not more, is already being used, either to evaporate water from the oceans or grow crops, or give us a nice tan on the beaches, or to light our cities, or whatever.”

    If you sacrifice some area of ecosystem (or roof and equatorward-facing exterior space, etc.) to make room for solar power devices (PV, CSP, CPV, luminescent concentrators, water heaters, hybrid systems, or skylights), then the resulting subtraction of solar energy from nature (or buildings) is not an issue – the nature isn’t there anymore. The solar heating is still an end result – maybe a little more or less than before, not enough to be significant on the global scale (maybe locally?). The water runoff still evaporates from somewhere – water runoff management should mitigate any large effects by keeping it from getting farther than otherwise. Except for presumably minor local/regional feedbacks (like the same kind you’d see around conventional power plants, cities, … irrigated croplands and deforested lands), the solar energy available on remaining land would be little affected. Photosynthesis will go on outside the panels, just as it does on suburban lawns (biofuel source?) and the wooded plots outside of cities, etc. Agriculture is already far more disruptive than anything solar power plants would ever do – make of that what you will (maybe we need to cut back on the meat… by the way, solar power plants on semi-arid lands could concentrate the water resource onto neighboring plots or the spaces in between panels, potentially boosting vegetative productivity there).

    Global energy use now is a bit over 10 TW (maybe 12 TW ?) of primary energy equivalent, which is 3 or 4 TW electrical equivalent. If the total array average panel/collector insolation is 200 W/m2, 10 % efficient conversion gives 20 W/m2 or 20 MW/km2, so 1 TW requires 50,000 km2 (well, now I’m just approximately repeating the post – but this continues). US electrical equivalent energy use would use a bit over 50,000 km2 (just under 0.5 % of U.S. area); global electrical equivalent energy use roughly 200,000 km2. How about this – multiply by 50,000 by 30 to bring 9 billion people up to US energy usage: 1,500,000 km2. Now let’s cut that in half for efficiency increases (can we do that? I’m not sure, but consider many people living at low latitudes won’t need as much energy for building and water heating, though they will want air conditioning): 750,000 km2. Global land area is roughly 150,000,000 km2, so 750,000 is 0.5 % of land area. Maybe 5 % of cropland, or 1.7 % of desert (depending on the definition of desert). Okay, we might have to multiply it by 2 or 3 to get actual land area used, but that doesn’t really affect the albedo change. (Bear in mind, global warming affects 100 % of the land surface and 100 % of the ocean surface.) By the time we get anywhere near this point, I’d expect solar PV efficiencies to have gotten significantly larger (which would allow greater generation on rooftops). Decreasing device costs would allow greater packing of collectors per unit land. Can most energy use be replaced by electricity? With transportation, mostly yes. A lot of building heating can be fulfilled with passive solar and maybe geothermal heat pumps (large buildings often don’t need any space heating). A significant portion of industrial processes can use heat supplied by parabolic trough concentrators – the heat will be larger than it’s electrical equivalent, but conversion of solar radiation to heat is considerably more efficient than 10 %.

  14. 264
    Patrick 027 says:

    Re 261 Lynn Vincentnathan

    “and my thinking is that first of all we have to get out there onto the curve.”

    Another way of looking at that is that we are on a slice through the PPC curve that doesn’t pass through the actual optimum – low hanging fruit will get us there. But investment in technology R&D actually reshapes the PPC, but then again, another way of looking at that is that the PPC over time has an optimum that we would miss (ending up on another point) if we didn’t make any such investments (or the capital goods investments associated with clean energy, etc.).

    “It seems to me the only thing lacking in this picture is “rational, economic man” — upon which the whole of economic theory is based, like a house built on illusory sand.”

    Well, another way of looking at that is that decision making resources are themselves scarce – rationality and information (in economics, information is part of rationality, correct? – but I mention it specifically because rationality could also be taken to refer to the ability to follow logic from given inputs to given outputs) has to be allocated to where it is most benificial, etc. – which is not to say that the supply of rationality and information cannot be changed by investments (rationality, etc, being a capital good of sorts).

    The bigger problem, I think, is the need for a public policy. Right now, we have a big unregulated externality, and individuals can behave as rationally as they want and still the whole suffers. (PS if you can get through my ‘rambling’, my thoughts here – and I’d be curious what you think of it (I’m just proposing a basic structure – I wouldn’t dare at this point to attempt to assign numerical values from the little I know):

    Big policy commnet 1 (MC1)

    Big policy comment 2 (MC2) (with a beginning portion focussed on technological issues outside the focus of this set of comments)

    Big policy comment 3 (MC3)

    additional points, clarifications/corrections, and summary:

    Summary of Summary:

    AND thoughts on the mathematical relationships between tax, public cost, mitigation spending, etc. (I was going through a reasoning process as I wrote this, whereas most of the previous parts I had thought of earlier in a broad sense – this isn’t to say any of this is necessarily original thought (except maybe point 13 ?), though it is what I would advocate – and not that I’m at all close to being an expert in any way in economics, but I understand some basics and I understand some concept of fairness and I was trying to put forward a basic structure, not filling in any numbers)



    and the comments immediately following (363, 364, 365), and




    and immediately following, 377, and


  15. 265

    Mark (238),
    You wrote: “But if we treat these farcical idiots to the contempt they so clearly and emphatically deserve, maybe they’ll stop yakking in shame.”
    No, they won’t. They’ll only become more idiotic and strong-headed as a result, and you give them a reason (not that they need one, I know) to taint all of us ‘AGW proponents’ as extremists, so the net effect of doing so is damaging. Perhaps the most vocal people out there in the discussion cannot be persuaded to abandon their opinions, but a lot of people are watching who may be more or less on the fence. Don’t push them to the other side. That’s what I’m worried about.

  16. 266
    Rene says:

    Mark (230)
    To clarify let me repeat the question not addressed by your message 200:
    – what word would *you* then recommend to describe someone who questions or doubts that AGW is a serious problem ?

  17. 267
    Foobear says:

    @Pranulis: “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.”

    Yeah, and water has been known to kill people when they inhale it at much lower levels. Therefore, we should slap a hazmat label on the local Sparkletts truck, right?

    As one of my chemistry professors put it, everything is poisonous; it’s just the concentrations that matter. At 100,000 ppm (1%), you’re talking about levels hundreds of times over our current atmospheric concentrations. And that’s not even a “poisonous” amount, just the lowest level signs of CO2 can be detected. You need to double or multiply 5-fold the concentrations to get into “poisonous” territory.

    So yeah, you’re not really helping the cause much by agreeing that CO2 “is a poison”.

  18. 268
    CM says:

    EL (#249), re Krauthammer on the UK personal carbon-card proposal: Yes, it’s clear how the columnist’s ideological opposition to a policy design (which I think is fair game) colors his view of the science (which is not). But blurring the ideological lines a bit, note that it was a Tory MP that fronted the idea after the Labour government had already put it on the back burner citing cost and unpopularity. Giving individuals ownership to their emissions and letting them trade, as an alternative to taxation, might appeal to the more cerebral free-marketeers on the right.

  19. 269
    Rene says:

    Lynn (261)
    The “rational, economic man” you imply is mythical, is someone who acts in his own best interests as he perceives them. Can you identify anyone at all who does not conform to this model?
    The reason the “low-hanging fruit” ideas you champion have not been adopted, is that people do not believe your analysis of their benefits, and maybe don’t even believe there is a real problem. And perhaps they’re right on one or both counts.

  20. 270
    Mark says:

    “Those who claim that using low energy lights will help haven’t done the numbers. Lighting consumes, on avearge, only 7 percent of dometic electricity consumption, and domestic elctricity consumption is only 7 percent of total average energy consumption”

    So removing a small amount will not help?

    Afraid you’re wrong.

    It’s not *enough* by itself, but then no one thing will be.

  21. 271
    Mark says:

    “Why are people taking the illustration here so literally? The point was to show that waste heat can’t possibly be a significant issue with solar cells – even in the extreme case where all the world’s current electricity needs came from PV solar cells.”


    It’s easy to get sidetracked when such dumb complaints about the square comes in though.

  22. 272
    Mark says:

    “Just one other thing, someone said that the UK government plans to buy solar energy from Jordan. I can’t see how – they’d need to build a helluva a lot of batteries to transport it”

    Uh, I don’t think they’ll use batteries, then.

    Strawman on fire!

    Maybe they’ll use some sort of lenticular conducting material at high potential to transport this electrical energy.

    But that’s just a hunch. We’d have to invent something like that first…

  23. 273
    Mark says:

    “The fact is that fully 98 percent of the energy falling on the Earth, if not more, is already being used, either to evaporate water from the oceans or grow crops, or give us a nice tan on the beaches, or to light our cities, or whatever.”

    Care to prove this?

    Because I think MOST of the radiation falling on the earth is reflected back (because we aren’t a perfectly absorbing body…).

  24. 274
    Mark says:

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

    And worrying about all those buggy whip manufacturers whose livelihoods depend on the horse trade…

  25. 275
    Mark says:

    “I think if your objective is to stop any skeptics posting here then you will probably be successful with your approach.”

    You think that is my objective, but you’re wrong.

    I don’t want skeptics to stop posting.

    Denialists would stop posting until AFTER they’ve thought it through.

    Since their arguments are so tenuous and flawed, this would result in their tenuous and flawed argument not being posted and I can’t see anyone being made worse off if that happens.

    Do you disagree?

    Or should any old cockamamie story be allowed?

    ” I’m surprised that you or those who set up RC would want it to work like that.”

    Maybe because you’re thought is wrong.

    Just a guess.

  26. 276
    Mark says:

    Tony Rogers, read Julia’s waste of space “argument” just before yours (#244).

    Do you think that gavin’s time was well spent there?

    It HAD to be spent, but was it *well* spent?

    Now do you think if Julia had given even one single thought to what she was rambling on about gavin would have had to ask the extremely basic queries that sum to pretty much “what they hell are you on about???” ?

    But if you treat barnpots who don’t think but parrot like sane people rather than barnpots parroting, will you teach them to think? Or do you think they’ll learn that sort of unthinking is acceptable?

    That is the stick.

    Gavin and others are much better at laying out a carrot but I praise even the dumbest previous commenter on asking a good question when they ask it.

    Carrot only doesn’t work.

    And that’s what you seem to want to see.

    PS See this from earlier:

    “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.”

    Hank Smith here, streamofconsciousnessbabbling his way to insanity.

    WTF is he talking about???

    Anyone know?

    It’s even poor grammar which if his same was Schmidt may be acceptable (English not his native tongue is then a possibility).

  27. 277
    David Kidd says:

    I have been looking at other sites while putting together a reading list for a friend of mine (Who is an accomplished artist and language teacher,not well versed in science and resident in China), that deals with trying to explain the facts behind what appears to be accelerated climate change. I came upon this contribution in “How to talk to a climate skeptic”
    Indeed, Real Climate is an extremely disappointing site. I’ve seen poor saps come there trying to legitimately understand the science behind AGW and they are treated rudely and shouted down the deities on the site. I tried to post a comment, just to say “lay off the guy”, and it was never posted. I was very disappointed, especially after I saw they continued to pile on the poor guy until he said “This is my last post”. I haven’t visited the site yet. Personally, I’m just trying to get information on this complex subject and am looking for a truly neutral site, not some place where high IQ scientists reveal why most people don’t take them seriously.

    you can see that while some scientist contributors to this site feel tired of being polite to the collection of crooks, shysters and those “on the take” who for their own reasons cannot or will not admit what is now becoming obvious we must NOT fall into the trap of treating them with contempt in print or “In the Media” in general. We must be polite and unflustered and if we get them to lose their cool well and good.We must never lose ours. It is like teaching a calf to drink from a bucket instead of from its mothers teat, care and some patience in acalm atmosphere will get you there. Swearing and pushing its nose into the milk in a bucket means total failure. Something I learned as a student of agriculture many years ago.
    I am sure Dr. leavitt and other academics are used to vigorous debate but ordinary people, not all of whom are used to written debate can be put off from following up and discovering for themselves important information.

  28. 278
    Mark says:

    “The “rational, economic man” you imply is mythical, is someone who acts in his own best interests as he perceives them. Can you identify anyone at all who does not conform to this model?”

    The rational economic man also requires free choice and be fully informed.

    Can you please tell me one single instance of this applying?

  29. 279
    Mark says:

    “I’ve seen poor saps come there trying to legitimately understand the science behind AGW”

    Really, David?

    I’ve seen people come here with canned leading questions that have been discussed for the past 30+ years.

    Other people have answered them with far more civillity than they deserve, but they still don’t listen or learn.

    You see what you want to see.

    PS read this link. It is about tech questions, but pretty much applies to ALL queries.

    Or try googling it before asking.

  30. 280
    Mark says:

    “Personally, I’m just trying to get information on this complex subject and am looking for a truly neutral site”

    What makes you say that this isn’t?

    Here is where you go for the neutral information:

    It’s where the science is done.

    If you want a potted history go to the “Start Here” button (weird how you saw so much yet missed that obvious answer to your quest whilst obsessing over the postings).

  31. 281

    Uh, Foobear, 100,000 ppm would be 10%, not 1%.

    Pretty toxic, actually.

  32. 282
    Rene says:

    Mark (278)
    Since noone can ever be “fully” informed, a rational man in the real world is one who acts logically on whatever information he does have, in ways he believes will best advance his aims, within whatever constraints he faces.
    Do you have any instances of this not applying?

  33. 283
    Mark says:

    Therefore you agree with Lynne: they don’t exist.

    “Do you have any instances of this not applying?”

    I don;t have to because that rational man is not the rational man that economic theory relies on.

    The rational man that economic theory relies on must be fully informed. This is not possible since there is a huge workforce DELIBERATELY crafted to post misinformation: marketers.

    The rational man that economic theory relies on must have free choice. This is not possible since there are many laws that enforce limited choice. For example, and not limited to: copyrights, patents, trade secrets, grey import laws and trade restrictions.

    I do not have to show that your “rational man” exists because your rational man is not one that partakes in economic theory.

  34. 284

    Interesting to contemplate the back-of-envelope estimate above of $11 trillion for solar development needed.

    Off the top of my head, I’d agree that it’s not too much; global GDP in 2008 was pretty close to $61 trillion, according to WIki. So could we spend 2-3% of GDP on a clean energy future?

    Well, in 2008, we–meaning the world as a whole–spent about $1.5 trillion on defence. So clearly we could. Which brings up the question, I suppose, of accurate threat assessment.

  35. 285
    KevinM says:

    @tharanga: Why are people taking the illustration here so literally?

    I think the idea of a giant solar farm in much more interesting than the actual subject.

    The thesis of the piece seems to be that a best selling economics author tried to speak outside of his area of expertise and got a lot of parts wrong. He’s just a big boring easy target.

    The interesting questions to me are:
    1) Is it reasonable to propose we start adding enough solar panels to be meaningful? Last I checked, solar was making less than 1% of US electricity.
    2) How many square meters of panels would it take, what would they cost, and what would the limitations be?
    3) Are there any interesting side effects?
    4) Are there better options? I like nuclear, and advocate that as a pet agenda. Someone commented there’s not enough Uranium, but with breeder reactors and ocean harvesting there would be enough for centuries. I could never effectively defend all of the pieces of the argument, I just try to mention it often enough that someone new might take time to investigate.

    Would you really have read 280 comments abnusing poor Dr Levitt?

  36. 286
    tharanga says:

    Mark, 273
    “Because I think MOST of the radiation falling on the earth is reflected back (because we aren’t a perfectly absorbing body…).”

    Global albedo is about 30%, maybe a bit higher. Hardly “most”.

    George Blahusiak’s idea (256) that using solar energy will somehow displace some other useful function of sunlight is muddled enough on its own. If you’re worried about crops, lighting and suntans, simply don’t place the solar cells above your crops, beaches or windows.

  37. 287
    Rene says:

    Mark (283)
    To deny the rational man of economics you need to show people acting against their own perceived best interests, using whatever information they have, acting within whatever constraints they face. Until you do you are ducking the issue.
    Your other ‘requirements’ of perfect information etc, however desireable, are quite irrelevant to the concept.

    [Response: Oh let’s see… umm… people selling CDOs and mortgage tranches they know will not perform but do so ‘because everyone else is’? Banks lending money to people they know have no chance of paying it back? People anticipating that bubbles will continue to inflate without end? None of this behaviour is long-term rational. Why did they do it? For short-term reasons based on complete ignorance (some of it wilful) of what the long term consequences would be. So, yes, absence of perfect information distorts idealised ‘rational behaviour’. – gavin]

  38. 288
    Mark says:

    “Global albedo is about 30%, maybe a bit higher. Hardly “most”.”

    And about 12% doesn’t get down to the earth’s surface, IIRC.

    OK, so not “most” but a lot more than 2%.

  39. 289
    Mark says:

    “4) Are there better options? I like nuclear, and advocate that as a pet agenda. ”

    We guessed.


    “Someone commented there’s not enough Uranium, but with breeder reactors and ocean harvesting there would be enough for centuries.”

    And in two centuries we have how much to clear up and no uranium left. The sun will still shine, the winds will still blow and the tides will rise and fall.

    Solve the bulk of our problems with renewables first.

    By then some of the reactors will have to be decomissioned and you can work on making them breeders. Though you WILL have to let Iran have breeder nuclear power without threatening to invade them. If not, give them all the free electricity they want. I.e. pay them NOT to persue their own power systems. We’ll also have a better hold on what works and what doesn’t. and maybe *safe* microgeneration so that nuclear doesn’t fall foul of the transport losses that it has at the moment and solar can largely avoid.

  40. 290
    Geoff Wexler says:

    re #9

    “Ocean acidification is “utter nonsense” said Piers Corbyn.”

    This was one of the ‘news items’ described here:

    That assertion alters the a posteriori probability of Corbyn being correct about the rest of his climate theory, which he was promising to announce at his conference, now summarised by the BBC’s Richard Black. If you remember that was the conference announced recently in a naive report by Paul Hudson who is very different from Richard Black. I hope that Black got in first this time.

  41. 291
    Hank Roberts says:

    Mark recommends above one of my long-favorite references, on how to ask questions the smart way. Here’s the part relevant to giving good answers.
    He sets a high bar, worth reaching for:
    How To Answer Questions in a Helpful Way

    _Be gentle._ Problem-related stress can make people seem rude or stupid even when they’re not.

    Reply to a first offender off-line. There is no need of public humiliation for someone who may have made an honest mistake. A real newbie may not know how to search archives or where the FAQ is stored or posted.

    If you don’t know for sure, say so! A wrong but authoritative-sounding answer is worse than none at all. Don’t point anyone down a wrong path simply because it’s fun to sound like an expert. Be humble and honest; set a good example for both the querent and your peers.

    If you can’t help, don’t hinder. Don’t make jokes about procedures that could trash the user’s setup — the poor sap might interpret these as instructions.

    Ask probing questions to elicit more details. If you’re good at this, the querent will learn something — and so might you. Try to turn the bad question into a good one; remember we were all newbies once.

    While muttering RTFM is sometimes justified when replying to someone who is just a lazy slob, a pointer to documentation (even if it’s just a suggestion to google for a key phrase) is better.

    If you’re going to answer the question at all, give good value. Don’t suggest kludgy workarounds when somebody is using the wrong tool or approach. Suggest good tools. Reframe the question.

    Help your community learn from the question. When you field a good question, ask yourself “How would the relevant documentation or FAQ have to change so that nobody has to answer this again?” Then send a patch to the document maintainer.

    If you did research to answer the question, demonstrate your skills rather than writing as though you pulled the answer out of your butt. Answering one good question is like feeding a hungry person one meal, but teaching them research skills by example is showing them how to grow food for a lifetime.

  42. 292
    tharanga says:

    285, Kevin:

    Those are indeed interesting questions, but they’re pretty comprehensively discussed elsewhere. I don’t think any reasonable person expects 100% of electricity or energy to be generated in the same manner; different technologies will have wedges of market share, just as they do now. Ultimately, it all comes down to dollars and cents, and whether you are optimistic that solar will soon be cost-competitive, or not.

    I suppose this topic does speak to your #3 point, about perverse side effects. At the risk of belaboring the point, I remain a bit disappointed that the discussion has not gone into the life cycle analysis very much. The energy payback period is currently maybe 2 years, which is pretty good, but worth keeping in mind. Renewables are great, but if the financial payback period is too high, they won’t be built, and if the energy payback period is too high, they shouldn’t be built.

  43. 293
    Nick O. says:

    Slightly off topic, but has anyone any thoughts on the latest Arctic sea ice trend?
    It’s tracking very closely the Autumn section of the minimum record curve set in 2007, and I was just wondering what this might bode for the coming year. For example, our own Met Office (UK) is forecasting a milder than normal Winter (mainly bsed on sea temps, I think, and NAO patterns, but I confess I didn’t look into it that closely), so does that mean we should be watching for the trend to dip below the 2007 curve fairly soon?

    Also, any news about the Wilkins and Pine Island Bay areas recently, anyone?

  44. 294


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

    1. In practice, denying that AGW is an extremely serious problem is as counter-empirical as denying that it exists, so there is no reason not to use the terms interchangeably.

    2. “Denialist who wants a more respectable name.”

  45. 295


    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.

    But a hell of a lot more expensive, requiring much more time to deploy, and much more potentially dangerous in a variety of ways.

  46. 296
    Tony Rogers says:

    I would like to make a further comment about my original post #26 about urban waste heat. I appreciate that it is not about solar panels and that the inference of the question irritates some here but I had hoped for some comments about how wild my assumptions may have been, whether my calculations were in the right ball park and if the answer was “interesting” in terms of urban temperatires.

    Further Googling seems to indicate that my assumptions/calculations were actually pretty close. For 2000, I calculated worldwide fossil fuel energy as 4.26 x 10^20 J. I estimated that 50% of the population was urban. I estimated population density as around 4750 / km^2 (based on London) and used that to calculate worldwide urban area.

    The final assumption was that 90% of energy was used in urban areas. Clearly, this has to be in the range 50-100% and is closer to 100% than 50% so 90% seems not unreasonable.

    So, based on 90% of the worlds fossil fuel energy use and the urban area estimated from population density, I get a figure for urban waste heat of around 20 W/m^2.

    So, I ask again, how significant is that much waste heat to an urban area?

  47. 297


    I’m not sure why hard core environmentalists continue to hate nuclear.

    They think radioactive contamination of the environment and the prospect of terrorists getting hold of nuclear materials to be bad things.

  48. 298
    Radge Havers says:

    Bart #265

    I often wonder about the fence sitters and the deniers and the culture at large. It’s hard to get a handle on.

    Concern about tone often assumes that the “battle”, while not logically equal is waged on psychologically equal terms, and that each side is causing the other to escalate and would otherwise be arguing in good faith. I don’t think this is the case. Much of what you see posted by deniers amounts to a sort of ad hoc psyops campaign. If you’ve noted the rise of right wing radio, you know that this sort of thing has potency. Pushing back may well have some effect in taking a bit of the windy triumphalism out of wingnuttia’s glorious sails. This may be distasteful to some people’s better instincts, but it throws a spanner in the works regarding fence sitters who might be otherwise be swept up in denialist hysteria.

    This is far from an ideal situation, but I don’t see this de-escalating until it’s in the denialists ideological or economic interest to take a different tack. Having said that, I would never try to dissuade someone from taking the high road. The whole point of all this is to keep the light alive as best we can.

  49. 299
    Jeffrey Davis says:

    “I’m not sure why hard core environmentalists continue to hate nuclear.”

    Don’t know what “hard core environmentalists” means.

    For me, off the top of my head, the impediments to wide spread substitution of nuclear energy in the grid seems to include: the amount of water required, the hazardous waste it produces, the hidden expenses that have dogged the industry in the past, the absence of trained workers, and the susceptibility of the cores to be weaponized.

    Environmentalists have been blamed for the lack of widespread adoption of nuclear in this country, but look at issue through the eyes of Iranians. We simply won’t let them develop their own nuclear industry. I imagine the same would be true for 90% of the countries on the planet.

    “Would you really have read 280 comments abnusing poor Dr Levitt?”

    Poor Dr. Levitt (or someone else interested in selling his book) has sent me spam. Apparently the poor doctor’s last book sold in the millions and people are interested in a repeat. A little controversy sells books. I don’t think poor Dr. Levitt is crying over the abnuse. The abnuse seems to be working out very well for him.

  50. 300
    Steve says:

    I work for a real estate developer/investor in California. I have looked into solar for our properties (mostly shopping centers) and it’s still not going to happen – too expensive to attract private investors, and the banks aren’t giving out any money right now. And that’s after including all of the subsidies/incentives we have here in California.

    As far as the albedo/waste heat issue, that’s the stupidest argument against solar that I’ve ever heard. The proposed solar cells for our shopping centers, for example, would be arrays in the parking lot. They would provide shade for cars, and I seriously doubt they would heat the earth any more than the black asphalt they would be covering. Maybe if you calculated that they would normally have white cars parked there all day.

    But… for a small shopping center (50K-75K sq ft) you’re looking at a $2M investment when the annual electric bill is only about $50K. Even after selling electricity back to the grid during peak hours, the minimum return on costs is 10 years. I don’t expect solar to take off until the government incentives get better, the costs of solar installations come down and/or the cost of otherwise cheap electricity shoots up. A combo of all three will eventually bring a boom in commercial solar installations. This recession isn’t helping, that’s for sure.