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Les Chevaliers de l’Ordre de la Terre Plate, Part I: Allègre and Courtillot

Filed under: — raypierre @ 18 November 2007 - (Français)

France has a per capita carbon emission of 1.64 tonnes, compared to 2.67 tonnes for the U.K and 5.61 tonnes for the US. So, if anybody has earned the right to rest on their laurels and pontificate to the rest of the developed world about what they should be doing, you’d think it would be France. Far from it, under the leadership of Nicolas Sarkozy, France has embarked on an ambitious program of deeper carbon reductions. In introducing the measures, Sarkozy said "The guiding principle is that the cost to the climate — the carbon cost — will be integrated into planning of all major public projects, and into all deliberations affecting the public." These measures include: a commitment that all new buildings would be net energy producers by 2020, incandescent lighting would be banned by 2010, buyers of efficient vehicles would be subsidized, drivers of inefficient vehicles would be penalized, and road construction would be severely curtailed in favor of expanded rail travel using state-of-the-art French TGV technology. A carbon tax is also being seriously contemplated. These proposals are the result of an intensive months-long series of discussions with scientists and stakeholders such as environmental nongovernmental organizations, industry representatives, and labor union representatives. The process, known as Le Grenelle de l’Environnement, was described here by Nature (subscription required) and a summary of some of Sarkozy’s proposed actions was reported in the press here.

All the same, there has been some pushback from a vocal pair of highly decorated French academicians, Claude Allègre being the most prominent and noisiest of the two. In recent years, Vincent Courtillot has emerged as a reliable sidekick to Allègre — a Dupont to his Dupond — helping to propagate Allègre’s claims and adding a few of his own. Both are members of the Académie des Sciences, and Allègre has been awarded both the Crafoord Prize and Bowie Medal. Allègre has an impressive list of publications relating to the Earth’s interior, and besides that was Minister for Education, Research and Technology in the Jospin government. Courtillot — currently director of the Institut de Physique du Globe de Paris (IPGP) — has had a distinguished record of research on fundamental aspects of geomagnetism and is currently President of the Geomagnetism and Paleomagnetism Section of the American Geophysical Union. Their views were amply (some would say more than amply) represented at a symposium on the IPCC report, held last Spring at the Academie (See the issue "Evolution des Climats" of La Lettre de l’Académie des sciences, and press reports in Le Figaro, Le Monde, and Liberation). What does all this mean? Are the opinions of Allègre and Courtillot founded on some special profound insight that has escaped the notice of the community of scientists who have devoted entire careers to studying climate? Let’s take a look.

When an active scientist of the distinction of Allègre or Courtillot speaks out, the voice has a special claim on our attention, no matter how implausible the claims may seem. It would be a mistake, however, to accept the proclamations of such luminaries on the basis of authority; one must examine the arguments on their merits. Allègre does not publish his arguments on climate in the peer-reviewed scientific literature, so we have to turn to his popular writings and public statements to get a glimpse of what these arguments are. A treasure trove of Allegrisms (Allegrories? Allegrations?) can be conveniently found in a little opus humbly entitled Ma vérité sur la planète (Plon/Fayard:Paris 2007). Many of the things said here merely parrot standard discredited skeptics’ arguments without adding anything new: For example, Allègre at several junctures repeats the old fallacy of confusing unpredictability of weather with the problem of determining how climate responds to changes in radiative forcing: "I have difficulty believing that one could predict with precision the temperatures that will occur a century from now, when we can’t even predict what they will be one week from now." (p.89) He also repeats the fallacy that the lead-lag relation between CO2 and temperature in Antarctic ice cores proves that temperature causes CO2 variations rather than vice-versa — a tired and thoroughly discredited argument (look here for a summary of the rebuttals) . There is little more to say about such arguments, save that Allègre’s willingness to repeat them shows either a remarkable gullibility or a disturbing lack of scientific integrity.

Elsewhere, though, Allègre breaks new ground with regard to passing off nonsense as scientific argument. Here are a few examples.

  • Allègre claims that the disappearance of the glaciers on Kilimanjaro is due to moisture supply changes arising from tectonic uplift, and has nothing to do with global warming. This claim appeared over a year ago in Allègre’s column in L’Express, and was discussed in an earlier RealClimate post on Allègre. Essentially, Allègre failed to understand that the tectonic events referred to in the Science paper he cited affected the African climate millions of years ago, whereas the present Kilimanjaro glacier didn’t even come into existence until around 10,000 years ago. The erroneous claim about Kilimanjaro is repeated in Ma vérité sur la planète (p.120), despite ample time and opportunity to correct the mistake. So much for vérité ("his" or otherwise).
  • Allègre says that "common sense" casts doubt on the idea that CO2 could have such a controlling effect on climate, because its concentration is only 300 parts per million (p.104). This "common sense" flies in the face of over a century of meticulous physics going back to the time of Tyndall, which shows precisely why certain trace gases have such a strong influence on infrared absorption by the Earth’s atmosphere.
  • Allègre says we "know nothing" (p.109) about the Dansgaard-Oeschger events and other form of millennial variability appearing in the ice-core record. From this statement, I think you are supposed to infer that since we "know nothing" about the events it could well be that the current warming is just the latest warm phase of such a thing. To be sure, there’s a great deal still to be learned about millennial variability, but the phenomenon has been the subject of several hundred peer-reviewed scientific papers, dozens of conferences, and a major study by the US National Academy of Sciences. We know enough about the pattern of such events and the mechanisms involved to essentially rule out the possibility that the recent warming is a related form of natural variability. We also know enough to worry about the possibility that climate change due to greenhouse gas increases could trigger massive ocean circulation shifts of the sort that were involved in past millennial variability.
  • Allègre says that under an increase of CO2 there would be no warming at the equator, whereas the predicted warming at the equator is in fact only somewhat below the global mean warming. He states correctly that the warming is strongest at the poles, but states without support that a 10ºC warming would be no big deal (p.122). This is quite a startling statement, given that a much more moderate warming has already caused substantial loss of Arctic sea ice. Part of his misconception may come from the fact that he thinks that the temperatures at "the poles" range from "-30 to -60ºC." (p.122) If that were really true, there would be no open water in the Arctic at the time of the sea ice minimum. It is easily verified that this is not the case, and indeed the Arctic commonly gets up to 0ºC in the summer, and sometimes more.
  • Ignoring the numerous independent studies of the instrumental record of the past century, he says the Phil Jones analysis of this data has been "put seriously in doubt" (p.100). And by what means? A comparison of Jones’ global mean data with an unpublished analysis of the average of a limited number of hand-picked European stations — presented as the epitome of the Geophysicists’ incomparable expertise at time-series analysis! More on this when we come to discuss Courtillot.
  • Helpfully, Allègre advises modellers that "It is necessary to avoid basing predictions of future climate on a global mean whose status is vague." (p.106) Evidently he is unaware that general circulation models have been simulating geographical variations of future wind and temperature changes at least since the 1970’s, and that maps of such changes have been included in every IPCC report going back to the very first. Oh, but I forget. Elsewhere Allègre states that "nobody reads" the IPCC reports (p.115). Evidently, this statement applies to at least one person.
  • Continuing his display of ignorance of the modelling enterprise, Allègre wonders why modellers put CO2 in their models, and concludes that it is only because they happen to know how it has varied over the centuries. Could a century of meticulous laboratory and field work documenting the radiative effect of CO2 perhaps have something to do with modellers’ preoccupation with this gas? Evidently not in Allègre’s universe. But there’s more: "Because one doesn’t well understand how clouds form, one neglects them! Because one has not mastered the role of aerosols and dust, one neglects them!" (p.104) This is not at all true. Clouds, aerosols and dust (as well as solar irradiance variations and volcanic eruptions) are all included in modern models. Models that leave out the influence of the CO2 rise fail to reproduce the warming of the past 30 years, and it is precisely for this reason that CO2 is confirmed as the prime culprit in global warming.
  • Allègre makes a number of false or misleading statements concerning the contents of the IPCC Fourth Assessment report. He claims that this report (contrary to French media coverage) "considerably toned down" its conclusions compared to previous reports (p.119). By way of evidence, Allègre states "For a doubling of CO2 emissions the temperature of the globe will rise between 2 and 4.5ºC in a century. The previous report said between 1.5 and 6ºC." (p.119) First of all, the IPCC statements on climate sensitivity refer to a doubling of CO2 concentration, not CO2 emissions, but let’s give Allègre the benefit of the doubt and assume this is just another instance of sloppy writing rather than true misunderstanding. Even so, Allègre is mixing up his apples with his pommes de terre in this statement. Though the climate sensitivity range narrowed from 1.5-4.5ºC previously to 2-4.5ºC now, reducing the likelihood of low climate sensitivity, the range of predictions for 2100 remain largely unchanged (and are moreover not strictly comparable between the reports given changes in the way "likelihood" is estimated). In a similar vein, Allègre claims that the IPCC reduced its forecast of sea level rise, which is not the case.
  • And there’s more. He says that IPCC has "modified, though not completely abandoned, its argument concerning 20th century temperature rise." (p.119) This evidently refers to Allègre’s belief that one of IPCC’s main arguments has been that CO2 must be responsible for temperature rise because (ben voilà!) they both go up! It’s hard for IPCC to abandon an argument it never made, and in any event the Fourth Assessment Report probably devotes more space to discussing the twentieth century temperature record, using more techniques, than any earlier report. And yes it does (pan to shot of Galileo here, speaking through clenched teeth as he bows before the inquisition) still go up (and by essentially the same amount as previously estimated). Continuing the theme of abandonment, Allègre says that the IPCC has "abandoned" its argument regarding the implications of ice-core CO2 and temperature variations. Actually, not. There is no change in the way IPCC interpreted the Vostok isotope and CO2 curve, which appears both in the 2001 and 2007 reports (the latter with Epica extensions into earlier times). The discussion appears in Chapter 6 of the Fourth Assessment Report (p 444 fig 6.3), but how could Allègre be expected to know that? Nobody reads the IPCC reports, right?

Misconceptions and misrepresentations of the sort given above are liberally supplemented with the usual arsenal of innuendo and quote-mining. Because Christopher Landsea (extravagantly compared to Galileo!) chose to make a scene by resigning from the IPCC, the whole process is deemed to not allow dissent — conveniently ignoring that Lindzen happily stayed on the IPCC Third Assessment Report. An entirely reasonable and uncontroversial statement by Dennis Hartmann on modelling uncertainties is twisted to imply that modellers think we can’t simulate anything with sufficient precision to draw conclusions about future warming (p.105). Quotes on the possible necessity of adaptation measures from MIT’s Ron Prinn and Columbia’s Wally Broecker are used to imply that these two notables favor adaptation over CO2 emissions reduction (p.126). And on the subject of adaptation vs. mitigation, some of Allègre’s statements are downright bizarre: He says that we have nothing to fear from global warming. After all, we adapted to the ozone hole, didn’t we? We adapted to acid rain, didn’t we? (p.127) Well, no actually, we did nothing of the sort. We "adapted" to the ozone hole by passing the Montreal Protocol to control CFC emissions. We "adapted" to acid rain by passing pollution control measures which reduced sulfate emissions. If this is "adaptation," I guess I can just say: ‘d’accord!’ Let’s just "adapt" to global warming by reducing CO2 emissions!

What is to be said of such claims? I couldn’t put it better than Allègre himself: "… une imposture intellectuelle, une escroquerie!" (p.107)

Whatever agenda Allègre is pursuing in his public pronouncements on global warming, it would seem to be very little informed by his scientific expertise. Through his litany of errors, misconceptions and misrepresentations, he has abdicated any claim to be taken seriously as a scientist when he speaks about climate change. And lest Lomborg and similar eco-Pollyannas draw too much comfort from Allègre’s support, let us note that, at the end of the day, Allègre still calls for a 20% reduction in CO2 emissions over the next 20 years. Many of us who wouldn’t touch Allègre’s arguments with a 10 foot baguette would be quite happy if such a plan were enacted in the United States, at least as a first step towards ultimate deeper reductions.

So much for Allègre. Now what of M. Courtilllot? Fortunately, we need not go into nearly so much detail, since almost all of the arguments presented in the Academie debate (see his article in La Lettre de l’Académie des sciences) mirror those given in Allègre’s book. Still, the man manages to add a few wrinkles of his own. For example he confidently declares that the glacial-interglacial CO2 variations are "simply" explained by the effects of temperature on CO2 solubility. He is evidently unaware that this simple mechanism was in fact quite simply evaluated years ago by Wally Broecker — like Allègre, a Crafoord prize winner — and found to be woefully insufficient (see Martin, Archer and Lea, Paleoceanography 2005, for a recent treatment of the subject).

Remember the graph of European temperature in Ma vérité which was supposed to put Phil Jones’ analysis of the instrumental record "seriously in doubt?" Well, it reappears in Courtillot amply decorated with a lot of new verbiage: climate scientists spend all their time modelling and hardly any looking at data; geophysicists are uniquely qualified to look at time series because they do it all the time and anyway they invented most of this stuff in the first place; nobody ever cross-checks or verifies Phil Jones’ work. And patati, and patata, none of which holds a glimmer of truth. But, having declared all this the brave geophysicists of the IPGP decide to take a look for themselves by averaging together a few tens of European weather stations (with a few distant ones from the Urals thrown in for good measure) and ben voilà, how Courtillot is "astonished" that the curve doesn’t look at all like what they were taught it should look like! (Courtillot is evidently a man easily astonished, and equally easily surprised, since these words appear with stunning regularity in his article.)

The analysis which evidently shocked Courtillot like a coup de foudre was presented at the Academie debate by Le Mouël (himself an Academician, and holder of the Fleming Medal). A video of his talk is here. Dear reader, I urge you to take a look at this video for yourself and see if you can make any more sense of it than I could, amidst all the mislabeled graphs, bizarre choices of what to compare to what, and missing information about crucial aspects of the data handling. I have done my best to convey what I think is the essence of the argument Le Mouël is trying to make, but it isn’t easy. In the left panel below I reproduce the only graph in which Le Mouël attempts a direct comparison between his data and the Phil Jones analysis which appeared in the IPCC report; it was redrawn by tracing over a freeze-frame of Le Mouël’s presentation. The graph is labeled "European Average" in the presentation, but the data (thin black line) which Le Mouël compares to Jones’ European analysis (red line) is actually from Denmark. Moreover, Le Mouël’s data seems to be monthly (or maybe daily) minima. Why one would want to compare Danish temperature minima with all-Europe temperature means is beyond me, but in the end what Le Mouël is making a big noise about is his claim that the yellow curve fit describes the data better than Phil Jones’ curve. Given the variability, there is really no objective reason to prefer one over the other, but the distinction between the two fits is largely immaterial. What you can take home from Le Mouël’s analysis is that, in Europe, a marked temperature rise does not set in until the 1980’s. Sound familiar? It should, because that is more or less what the IPCC says, pointing out further that natural variability cannot explain the recent warming. This can be seen well in the right panel, taken from the Fourth Assessment report. The blue shaded region is the ensemble of simulations forced by natural variabiity, while the pink shaded region includes anthropogenic forcing. Only the latter reproduces the rise at the end of the record.

The point of a lot of this fiddling with temperature curves is that the Sun must be doing something to control all these fluctuations. That brings us to radiative forcing, and Courtillot and company have had some problems with this issue, since they have a hard time making it look like CO2 is a small forcing and solar variability is a big forcing. One botched attempt at this was to claim that cloud fluctuations swamp CO2; Courtillot claims that clouds cause 80 Watts per square meter of radiative forcing, so that a mere 3% change in cloud cover would cause 2.4 Watts per square meter radiative forcing, which would be comparable to greenhouse gas forcing changes to date. To get this figure, though, Courtillot evidently assumed that all the Earth’s albedo is due to clouds, and moreover neglected the cloud greenhouse effect. When properly calculated, the net cloud radiative forcing is more like 20 Watts per square meter, so a 3% change gives you only 0.6 Watts per square meter, well below the greenhouse gas radiative forcing to date, to say nothing of what is in store for the future.

This flub is nothing compared to the trouble Courtillot’s collaborator Le Mouël got into during the debates, when he was trying to show that the 1 Watt per square meter variation in the Solar irradiance over the solar cycle is fully half the greenhouse gas forcing. Well, there is the little matter that Le Mouël forgot to take into account the sphericity of the Earth (which means divide the solar irradiance by 4) or its reflectivity (which means take 70% of the result). As the Le Monde reporter archly noted, Le Mouël’s calculation assumes a black flat Earth, but, "Hélas! La Terre est ronde" (zut alors!). Le Mouël seems eager to follow in Allègre’s geometrically-challenged footsteps: In a 1988 book (12 clés pour la géologie, Belin:Paris), Allègre confidently stated that the pole to equator temperature gradient was due to snow albedo and atmospheric absorption, making no mention of the role of the Earth’s spherical geometry, which is far and away the dominant factor (and the reason there’s ice at the poles to make a high albedo). Messieurs, here’s a little hint: What does the "G" stand for in "IPGP?"

The round Earth having robbed him of his 1 Watt per square meter –which in any event is mostly averaged out over the relatively short solar cycle leaving a miniscule tenth of a Watt variation between cycles — Courtillot grasps at the possibility some unknown and unquantified nonlinear mechanism for turning the very high frequency solar variability into a century scale trend.

There is also a bit of nattering about Moberg’s take on the Hockey stick, the supposed considerable warmth of the Medieval Warm Period, and some supposed millennial solar variability which supposedly accounts for why the present warming sort of looks like Moberg’s take on the Medieval Warm. Even leaving aside evidence that Moberg’s method exaggerates variability (see Mann, Rutherford, Wahl and Ammann 2005, available here), the "blame the Sun" mantra falls apart because neither the Sun nor cosmic rays have been exhibiting any trend that could conceivably account for the recent warming, as we have discussed in many places on RealClimate (most recently here).

With regard to climate, Courtillot’s main claim to fame is not found in his article in La Lettre. For that we have to look to a paper recently published in EPSL, which claims that climate variations are closely tied to the geomagnetic field. How convincing is this work? That will be the subject of Part II.

291 Responses to “Les Chevaliers de l’Ordre de la Terre Plate, Part I: Allègre and Courtillot”

  1. 251
    Phil McCracken says:

    We need more nuclear power plants world wide! Vive la France! We don’t have to worry about the steam emitted, right?

  2. 252
    Hank Roberts says:

    Jim, here’s the flaw in the chain of logic:

    > the lower the maximum sunspot number the cooler the earth

    That assumes that the Earth’s temperature varies along with the sunspot number. This hasn’t been true for decades.

  3. 253
  4. 254
    Lynn Vincentnathan says:

    RE #246 & 249, I’ve mentioned several times here that the solar increase is a serious consideration, esp in conjunction with the warming we are causing. It would require us to reduce our GHGs all the more, so as to not only reduce the warming we’re causing, but also the extra warming the sun is causing.

    Luckily the scientists here have assured me that such increase in solar warming is not expected for a long, long time.

    Still I think it best to reduce our GHGs ASAP AMAP (as much as possible), because you never know when other forcings, like volcanic emissions, or feedbacks (like GHGs released by nature due to the warming) might surge up greatly.

  5. 255
    Lynn Vincentnathan says:

    Sarkozy is doing very well. And now Australians have taken a giant step in the right direction by electing a person who says he’ll ratify Kyoto ASAP. See:

    Now the U.S. will be all alone as a Kyoto spoiler.

  6. 256
    bobn says:

    Have a quick question about the greenhouse effect if anyone can help. Im just confused about some simple part of it. I can sum it up as one question – is there backradiation from nitrogen and oxygen molecules? My confusion is because I think they must radiate energy in some form, and some must go down and be absorbed by the surface. But wouldn’t that mean non-greenhouse gases were contributing to the greenhouse effect?

  7. 257
    Philippe Chantreau says:

    Re 250: For reasons abundantly discussed on this site, the steam is not nearly as much of a problem as the warm water effluents.

  8. 258
    Nick Gotts says:

    RE #248 “the problem is: Cap and Trade doesn’t actually REDUCE CO2 production. It shifts it and masks it.”

    Depends entirely where you set, and whether you enforce, the cap. What I’m supporting is actually the “Contraction and Convergence” approach (

  9. 259

    #250 “We don’t have to worry about the steam emitted, right?”


    All that steam is safely in the ocean now (with a little bit of tritium in it, so if you still want to worry, there’s your chance), except last week’s, which is raining out as we speak ;-)

  10. 260

    Dave posts:

    [[the problem is: Cap and Trade doesn’t actually REDUCE CO2 production. It shifts it and masks it.]]

    It reduces it if you reduce the cap every year. That’s how we got acid rain decreased in the United States; by a cap-and-trade program on sulfur emission.

  11. 261
    Jim Cripwell says:

    Ref 251 Hank writes “That assumes that the Earth’s temperature varies along with the sunspot number. This hasn’t been true for decades.” I am lost. It does NOT assume “that the earth’s temperature varies with sunspot number.” It assumes that the earth’s temperature varies with the MAXIMUM sunspot number during each sunspot cycle. Each sunspot cycle lasts about 11 years, which is about one decade. During the 20th century, there have been about 9 solar cycles. Each of these cycles has had a maximum sunspot number above average for the time since sunspot numbers have been measured. The earth’s temperature has sort of risen during the 20th century. I think people are confusing sunspot number, which varies in a sort of regular way over each 11 year cycle, and maximum sunspot number during the cycle. There have only been 9 such numbers for the whole of the 20th century.

  12. 262
    Lawrence Coleman says:

    The french have always been ahead of the race in terms of the environment, they championed the adoption of nuclear power as their main source of energy, they built a highly efficient transport system and their latest proposals are yet again examples of their forward thinking and awareness of issuses most americans brits and australians are soo painfully slow at grasping and/or accepting. See they chose to accept what the scientists were saying well before the rest of us and rather than hope that the problem will go away they chose to tackle the problem head on. Actually France and Germany are champions in this regard. The Germans pay net energy producers a dividend whether they are a a nuclear power plant or a suburban house with solar cells on it’s roof. Now with solar cells becomming more and more efficient and no doubt subsidised heavily by the gov france can indeed afford to become a role model for all other countries to follow. In regard to incandescent lighting I have written to the management of our largest chain of supermarkets to phase out the sale of incandescents..response…”when the gov subsidises Compact fluoro lights to the point that they are a comparable price to incandescents”..Great leadership??

  13. 263
    Jim Eager says:

    Re Lynn Vincentnathan @ 254: “Now the U.S. will be all alone as a Kyoto spoiler.”

    Not quite. Unfortunately Canada’s conservative government, also a minority, btw, is still advocating only voluntary carbon “intensity” reductions, and just this week managed to prevent the Commonwealth nations from adopting binding mandatory cuts.

  14. 264
    Hank Roberts says:

    Jim, you’re saying that with a low maximum sunspot number the Earth cools.

    I’m pointing out that the change is heat from the Sun between peak and minimum is so slight — compared to the trend now — that it makes only a slight reduction in warming, not cooling.

    It’s a factor. It’s a very minor factor compared to the current rapid increase in greenhouse gases, and the warming already built in by those that will go on for some centuries til a new equilibrium is reached. Then only very slowly CO2 will get removed by natural processes, once we quit overwhelming them by adding it so very fast.

    Yes the Sun makes a difference. No, not a very big one compared to human activity this century.

  15. 265

    Re #255: apparently not… searching for the thermal infrared spectrum of N2 and O2 came up empty-handed. Even listings of IR spectra of atmospheric constituents don’t include them.

    I have heard that symmetric diatomic molecules of this kind don’t have the kind of band spectra that the greenhouse gases have. Being transparent to IR means according to Kirchoff-Bunsen also that they do not radiate in the IR.

    I remember from my glass-blowing course that glass, which is transparent to visible light, doesn’t glow in visible light either when heated up in the gas burner. A painful demonstration of Kirchoff-Bunsen if you’re not careful :-(

  16. 266
    Phil. Felton says:

    Comment by bobn ” I can sum it up as one question – is there backradiation from nitrogen and oxygen molecules? My confusion is because I think they must radiate energy in some form, and some must go down and be absorbed by the surface. ”

    N2 & O2 don’t radiate energy.

  17. 267
    Jim Cripwell says:

    Ref 263. Hank, I agree with you that “I’m pointing out that the change is heat from the Sun between peak and minimum is so slight — compared to the trend now — that it makes only a slight reduction in warming, not cooling.” However, the reason the earth is going to cool, as I have stated before, is because of changes in the sun’s magnetic and electrical properties, and has nothing to do with heat. Precisely how the changes in the sun’s magnetic and electrical effects causes the earth to cool down or heat up, we do not understand. But the correlation is such, that I for one, believe it will happen.

  18. 268

    bobn posts:

    [[Have a quick question about the greenhouse effect if anyone can help. Im just confused about some simple part of it. I can sum it up as one question – is there backradiation from nitrogen and oxygen molecules? My confusion is because I think they must radiate energy in some form, and some must go down and be absorbed by the surface. But wouldn’t that mean non-greenhouse gases were contributing to the greenhouse effect?]]

    Nitrogen and oxygen are very poor absorbers of infrared radiation, and therefore very poor emitters of IR. Most of the back radiation from the sky is from greenhouse gases.

  19. 269

    Jim Cripwell writes:

    [[ However, the reason the earth is going to cool, as I have stated before, is because of changes in the sun’s magnetic and electrical properties, and has nothing to do with heat. Precisely how the changes in the sun’s magnetic and electrical effects causes the earth to cool down or heat up, we do not understand. But the correlation is such, that I for one, believe it will happen.]]

    WHAT “correlation?” The biggest solar-Earth temperature correlation matches total solar irradiance, not something magnetic or electric. If you throw out TSI because it doesn’t match the recent rapid warming, you have to focus on things that match Earth’s temperature history even less. Sorry, you’re just not going to convince anybody that way.

  20. 270
    PJB says:

    To echo Paulina in 203, I would also like to thank the people who contribute to this site. You are doing the world a great service, and as someone who has read the comments for some time, your patience with, ahem, people who do not do their homework is extremely admirable.

  21. 271

    Phil Felton (#265) wrote:

    Comment by bobn, “I can sum it up as one question – is there backradiation from nitrogen and oxygen molecules? My confusion is because I think they must radiate energy in some form, and some must go down and be absorbed by the surface.”

    I hope you don’t mind if I give you the long answer rather than the short one. In all honesty I think your question requires it as I believe there are other questions behind it. But before getting into this, I should let you know that I am not an expert — just a computer programmer working in a completely different field. What follows is simply what I have learned while participating here. And I must admit that I am essentially going off memory, and sometimes my memory doesn’t serve me quite as well as I might like.


    What is the difference between line radiation and blackbody radiation?

    The absorption spectra of gasses are the same as their emission spectra. Or at least that is a good approximation. Essentially, what you are dealing with at that point is the fact that a good absorber is also a good emitter — for each wavelength. We refer to this as Kirchoff’s law. This applies to gasses, liquids and solids.

    In fact, the blackbody emission spectra is only an idealized case. Something which cannot exist in reality, although some substances are better at it than others. In all cases, you have bands, lines, band widths, line widths. Higher pressures will cause the bands to become wider, higher temperatures will cause the lines to widen, but the bands to become more narrow. And the lines and bands themselves are where the substance emits as the result of the decay of excited states.

    Water vapor isn’t linear, so you will have an electric dipole. As a result, you will have vibrational excitation and rotational excitation as well as states involving both vibrational and rotational excitation — refered to as rovibrational states. Carbon dioxide is however linear and symmetric. As such it has vibrational states, but no pure rotational states. However, as the result of assymmetric vibrations it can have rovibrational states.

    For each state, in the spectra you will see a series of lines representing the different points in the spectra where absorption and emission can occur. Some look like symmetric dampened oscillating curves if you look real close.

    However, the more interactions there are between the different molecules, the more the number of excited states which become available, and as such the spectra will come closer to the kind of continuous spectra than we normally associate with liquids and solids. But even in the case of solids you are actually dealing with spectra which ultimately are composed of lines and bands — if you look closely enough.

    With some solids you don’t have to look quite so closely. Dusts and crystals come to mind — as do various alloys. And typically, even with liquids and solids, the spectral emissivity (which is essentially a measure of how well the substance absorbs or emits at a given wavelength) will vary over the spectrum. We recognize this by says that there are no true black bodies, but there are also no true grey bodies — where the spectral emissivity would be constant over the entire spectrum.

    As such, I prefer to avoid speaking of line radiation and blackbody radiation. It is all realistic body radiation.


    But typically I will avoid even the phrase “realistic body radiation.” After all, gasses aren’t normally thought of as bodies, are they? Instead I will generally use the term “thermal radiation.”

    It is, afterall, thermal energy which is being gained when the substances absorb and thermal energy which is being lost when they emit. And above roughly 10 mb for gasses, the temperature at which the substance emits will be the same as the temperature of the substance itself. At each point in the spectra where absorption and emission takes place, there will be a brightness temperature which is the same as the Maxwell collisional-temperature of the substance itself.

    But why will the temperature of the spectra be the same as the collisional temperature?

    Each excited state is subject to quantum decay. This is a form of exponential decay over time such that an excited molecule has no memory of how long it has been excited, and for each unit of time that it survives, the probability that it will survive the next unit of time will be the same as all of the units before it.

    However, above 10 mb, there will tend to be a great many collisions, more than a million collisions taking place in the time that it would take the molecule’s excited state to decay — at least within the near infrared spectrum for temperatures found on earth. As such, the molecule which absorbs a photon will typically lose its energy to the surrounding gas.

    To a first approximation at least, the major constituents of our atmosphere (nitrogen and oxygen) will not emit. They are symmetric diatomic molecules, and as such any vibration which might exist will not be quantized any more than the translational energy that exists when molecules travel in a straight line is.

    However, they will collide with greenhouse gas molecules. Energy will be lost and gained during such collisions. And as such, all of the molecules which constitute the atmosphere will be at the same temperature.

    But this temperature will also extend to the excited states of the greenhouse gas molecules themselves. A certain percentage will be in an excited state at any given time — even when the energy associated with that excited state is considerably greater than the average kinetic energy of the molecules. Afterall, the Maxwell distribution of kinetic energy has a very long tail.

    As long as a certain percentage of greenhouse gas molecules are in an excited state at any given time, over a given unit of time, there will be a certain percentage that will undergo spontaneous decay. As such, we will say that the vibrational temperatures, rotational temperatures, and rovibrational temperatures of any given greenhouse gas will be the same as the translational temperature of the gas itself.

    However, these do tend to diverge below 10 mb — as there aren’t enough collisions to equalize the different temperatures. Above 10 mb, you will have a local thermodynamic equilibria where the temperature of the radiation field is the same as the temperature of the substance which is emitting thermal radiation, but below 10 mb, the temperature will begin to fragment into different temperatures for different states, resulting first in a partial-LTE, then a non-local thermodynamic equilibrium as the temperatures associated with different states all begin to diverge.


    But is it actually the case that oxygen and nitrogen do not emit? Well, oxygen is an interesting exception. It will emit very weakly as the result of a small magnetic dipole. But both will emit very weakly as the result of multiple collisions resulting in excited states. Now how exactly that works I do not know. But it is something which Hank Roberts brought up at one point.

    Incidentally, my apologies for not including the references for the above material. There are simply too many points. But if you have a few specific points that you are really interested in, I or others can probably find the literature readily enough.

  22. 272
    Paul Harris says:

    Re response to 176. Writing an updated Candide…now that’s something I could perhaps look at when I retire…

  23. 273
    catman306 says:

    #243 Lawrence Coleman concerning losing the carbon sink of the oceans:
    Please see Nov 1, posting Losing the carbon Sink and comments:

  24. 274
    Jim Cripwell says:

    Ref 268 Barton writes “WHAT “correlation?”. I am not sure why I bother. The coincidence of the Maunder minimum with the Little Ice Age.

  25. 275
    Ray Ladbury says:

    Re 266. Jim Cripwell, OK, now let me get this straight. You admit you have no model–hell, not even a glimmer of an idea that could one day become a model. You don’t even know if it is “electrical” or “magnetic”. In effect, you want to explain the unknown in terms of the unknown. But you want us to scrap a perfectly good theory that explains the data in terms of well understood physical processes known to be occurring. Uh, Jim, ever hear of science?

  26. 276
    Ray Ladbury says:

    bobn, re:255. People seem to get wrapped around the axle when it comes to “blackbody radaition” versus quantum radiation. A blackbody radiation distribution is just the energy distribution a gas of photons in equilibrium would have at a given temperature. It’s a property of the spin-1 particles we call photons. However, photons don’t interact with each other very much, so how do they come to equilibrium? They do so by interacting with matter. If the matter were a perfect black body, it would absorb perfectly at all wavelengths. Know such a material? Neither does anybody else. Real materials can only absorb photons where they have energy transitions that correspond to the photon wavelength. So, to first order, O2 and N2 do not radiate or absorb in the IR (no transitions corresponding to that energy difference). In reality, as molecules interact, the bonds get stretched, bent, bruised and otherwise tortured, and you get nonzero magnetic moments so you may get some weak absorption/emission at high densities.
    To understand blackbody radiation, I recommend the treatment in Landau and Lifshitz “Statistical Mechanics” book–it’s pretty clear. To understand the role of ghgs in climate, I recommend Ray Pierrehumbert’s book. Hope this helps.

  27. 277

    Ray Ladbury (#275) wrote:

    So, to first order, O2 and N2 do not radiate or absorb in the IR (no transitions corresponding to that energy difference). In reality, as molecules interact, the bonds get stretched, bent, bruised and otherwise tortured, and you get nonzero magnetic moments so you may get some weak absorption/emission at high densities.

    Thank you, Ray.

    That was the bit I was missing. Didn’t know that it was the same explanation as what I gave in terms of O2 for N2, but it makes sense. Meanwhile, I will have to get the Statistical Mechanics when I’m a little more sure about the finances. Already have Raypierre’s book, though.

  28. 278

    Ray Ladbury (#274) wrote:

    Uh, Jim, ever hear of science?

    Presumably Frank James got himself a PhD in physics, but obviously it didn’t help.

  29. 279
    Jim Cripwell says:

    Ref 274. Ray writes “But you want us to scrap a perfectly good theory that explains the data in terms of well understood physical processes known to be occurring.” Correction. All you have is a hypothesis. You cannot possibly call it a theory. There is absolutely not one single scrap of hard measured independently replicated experimental data that connects the recent rise in the concentration of CO2 in the atmosphere, with an alleged recent rise in the earth’s temperature, or anything else for that matter. I suggest you read “The Chilling Stars”. I dont want you to scrap you ideas. But I do wish you would stop pressuring our politicians to waste billions of dollars in an unnecessary attempt to reduce the emission of CO2.

  30. 280
    Julian Flood says:

    Re 216: is interesting. Looking at the cloud cover graph, the cloud amount rose up to 1987, then fell by 4% to 2001. That’s a lot of forcing. It then recovered slightly.

    quote For clouds, I assume mean cloud coverage of 61.7% (Kiehl and Trenberth’s 1997 figure). If the average albedo of the surface is 0.05, then clouds must have a mean albedo of 0.465 to reproduce the observed planetary albedo. If we then decrease cloud cover by 1%, RF changes by 0.96 W m-2. unquote

    So for 14 years we had up to an extra 4 watts/m^2. Comparing the graph with Hadcrut3 looks promising.

    quote The work of Palle et al. with Earthshine estimates of Earth’s albedo is very interesting, but not everybody buys his figures yet, much less the big annual changes. There may be some problems with his methodology. unquote

    Would you care to expand on the doubts?


  31. 281
    Jim Galasyn says:

    Re “an alleged recent rise in the earth’s temperature” in 278: Jim, this is an odd qualification, given that you’ve admitted the existence of a warming trend in other posts. Why is it suddenly “alleged” in this one?

  32. 282

    Jim Cripwell writes, bizarrely:

    [[Ref 268 Barton writes “WHAT “correlation?”. I am not sure why I bother. The coincidence of the Maunder minimum with the Little Ice Age.]]

    The Maunder Minimum was in TSI, Jim. TSI in the mid 1600s was around 1363 watts per square meter compared to the present 1366. TSI and sunspots tend to go together. Again, there’s no mysterious electric or magnetic force involved that correlates with climate history. It’s a simple matter of more or less sunlight.

  33. 283

    Jim Cripwell writes, even more bizarrely:

    [[There is absolutely not one single scrap of hard measured independently replicated experimental data that connects the recent rise in the concentration of CO2 in the atmosphere, with an alleged recent rise in the earth’s temperature, or anything else for that matter.]]

    What part of “the basic lab work was done in 1859” do you not understand? Or do you think the CO2 measurements from Mauna Loa are faked? I’m at a loss to understand your repeated statement that there’s no evidence. Are you just unaware of the evidence?

  34. 284
  35. 285
    Jim Eager says:

    Re Jim Cripwell @ 273: “I am not sure why I bother.”

    That makes at least two of us, probably a whole lot more.

    “I suggest you read “The Chilling Stars.”

    And you have the chutzpah to write “All you have is a hypothesis. You cannot possibly call it a theory”?

  36. 286
    David B. Benson says:

    From Hank Roberts (283) link:

    All of these changes characterize a carbon cycle that is generating stronger-than-expected and sooner-than-expected climate forcing.

  37. 287
    Jacques VILLAIN says:

    L’objection d’Allègre sur la domination écrasante de l’eau (par rapport au CO2) peut-elle être balayée au seul nom de “plus d’un siècle de physique méticuleuse qui remonte à l’époque de Tyndall”? Si j’en crois Weart( la majorité des météorologistes pensaient encore en 1950 que le CO2 était trop dilué pour jouer un rôle. Quant aux physiciens, quand ils avaient une opinion, c’était souvent la même (depuis Angström en 1900). Si je comprends bien, il y a essentiellement 3 raisons qui expliquent l’importance du CO2: 1) il y a amplification par la vapeur d’eau (par un facteur entre 1 et 5). 2) les bandes d’absorption de H20 et CO2 ne se recouvrent pas tout à fait. 3) Au dessus de 7000m environ, il y a plus de CO2 que de H20, et à plus basse altitude la chaleur se propage surtout par convection. Y a-t-il des analyses plus précises ou faut-il se résigner à croire les ordinateurs (ce que je fais volontiers, mais il est agréable de comprendre)?

    [Response: Voir aussi A Saturated Gassy Argument,What Angstrom didn’t know et Water Vapor: Feedback or Forcing? –raypierre]

  38. 288
    Hank Roberts says:

    Jim isn’t reading, but for others, see the links posted earlier.
    Quoting from the first of the three, from William Connolley’s blog:
    2005-03-31 Solar errors.
    For those of you interested in solar-climate connections, I strongly recommend reading DamonLaut2004.pdf from which one may quote gems such as: Analysis of a number of published graphs that have played a major role in these debates and that have been claimed to support solar hypotheses [Laut, 2003; Damon and Peristykh, 1999, 2004] shows that the apparent strong correlations displayed on these graphs have been obtained by incorrect handling of the physical data. The graphs are still widely referred to in the literature,and their misleading character has not yet been generally recognized. Readers are cautioned against drawing any conclusions, based upon these graphs ”
    ——end excerpt—–

  39. 289
    Steven mosher says:

    re 276. Hi ray.

    Look at the sheep.

  40. 290
    Ron Taylor says:

    For those of you who continue to try to refute the mindless statements of Jim Cripwell, you need to understand that he is following the well-established principle that “a lie repeated often enough becomes the truth.” (courtesy of Joseph Goebbels) That is why he keeps repeating nonsense that has been refuted multiple times in these threads. I really object to allowing him to continue to clutter up the discussions. If he has something new to offer, then fine.

  41. 291
    Charles Muller says:

    #287 Jacques
    De toute façon, il y a “domination” (terme impropre) du H2O sur le CO2 puisqu’une bonne part du réchauffement attendu provient de la rétroaction H2O, pas du CO2 lui-même. (Y compris “au-dessus de 7000m”, car la rétroaction de la vapeur d’eau est surtout sensible en haute troposphère et sur les Tropiques, du moins dans les modèles, voir ici la discussion récente du Douglass 2007). Sinon, je pense qu’il faut passer par des modèles (ordinateurs) pour calculer tout cela au-delà de la physique de base – cette dernière nous dit simplement que le CO2 absorbe et émet dans l’IR lointain, comme d’autres espèces H2O, CH4, etc.