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Unforced variations: Feb 2011

Filed under: — group @ 2 February 2011

This month’s open thread…

… continued here.

570 Responses to “Unforced variations: Feb 2011”

  1. 101
    Septic Matthew says:

    Here is another nice back and forth, if you read all the comments:

    Reportedly, the wind turbines did not all operate at their nameplate power the full time, but that’s a detail for later discussion; the wind farms collectively were generating about 7% of total demand, what I would call a respectable figure for this stage of what I hope will be a long-term development of a renewable energy economy.

    Despite the egg on my face now, I am encouraged. A concurrent event is the shortfall of natural gas in places in New Mexico and Texas.

  2. 102
    raypierre says:

    OK here’s the skinny on the interesting paper unearthed by Kevin McKinney in Comment # 90, and an update to my response to Comment 87, basically quantifying how “dry and cold” an atmosphere needs to be in order for most of the back-radiation to come from CO2 rather than water vapor. Any paper with Steve Warren on it is well worth reading, and I encourage everybody interested in this subject to read the paper Kevin linked. It’s very illuminating.

    You can actually get a handle on this question from Figure 6.1 from the surface energy balance chapter of Principles of Planetary Climate, which plots the surface radiative cooling factor vs. surface temperature and CO2 for both moist and dry atmospheres. I didn’t make up this figure with the particular question under discussion in mind, but you can still get an idea of what is going on from the figure. For fixed atmospheric temperature, the back radiation is proportional to 1-estar, where estar is the cooling factor I plot in the graph. Looking at the curve for 100ppm CO2 and comparing the wet and dry results, at 240K 1-estar is .35 for the wet case and .12 for the dry case,which is very close to the 3:1 total to CO2 ratio given in the paper cited. I don’t have a curve there for 380ppm but if you own the book you can try this for 1000ppm or use the software included to re-do the figure yourself. In any event, you’d expect some mismatch because the paper cited used actual measured temperature and humidity profiles, rather than the ideal. But anyway, we’re in the right ballpark. You have to go to temperatures of something like 200K before CO2 becomes dominant. Fig 6.1 also illustrates the point I was making in my comment, that as you go toward 300K, the water vapor almost completely determines clear-sky back-radiation. (N.B: Readers who have not yet had a chance to purchase the book can still follow this discussion by downloading the figures from the Resources tab on the CUP web site. That’s open-access, as is the courseware on my own site).

    Now, as to the puzzling result that summer and winter at the South Pole give similar H2O/CO2 emission ratios, the paper does some nice radiative transfer modelling which shows that this is mostly because the South Pole water vapor fluctuates in a range where the dominant contribution to water vapor opacity is fairly much radiatively saturated, so that the emissivity contributed by water vapor is rather insensitive to water vapor concentration over this range. That would break down at significantly lower or significantly higher water vapor mixing ratios. I leave it as an exercise to the reader to use the Pythonized CCM radiation model provided with the courseware to see how well the CCM model reproduces this effect, and where the effect breaks down.

    Altogether neat! You learn all sorts of interesting stuff by reading RealClimate. I think I will include something on this in the second edition of Principles of Planetary Climate, and in the meantime add some problems on this to the supplementary online problems for Chapter 6, once I start putting those up on the web site.

  3. 103


    A quick, hopefully easy question. Imagine a completely arid world with an O2/N2 atmosphere completely devoid of greenhouse gases, and with a relatively slow rotational period, so that the ground on the sun side can heat greatly while the night side can cool greatly.

    Will the atmosphere ever heat to any notable degree (as such heating is limited to conduction at the very surface)? If the atmosphere succeeds in warming, can it in turn warm the cooled night side surface to a notable degree?

    And what if the rotation is quickened, so that the night/day difference is minimized and the surface can achieve a relatively stable temperature?

    [Response: In fact, I do exactly this case, though without O2 (which doesn’t matter anyway) in my ApJL paper about Gliese 581g. That paper is available through my publication site. The atmosphere still heats, but the interesting wrinkle is that the ONLY energy exchange is the turbulent exchange between the surface and atmosphere. Absorbed stellar energy is just reradiated directly from the surface. Nonetheless the atmosphere heats up by turbulent transfer (not just conduction) and if the rotation rate is slow enough it will carry heat to the night-side. In the paper I only discuss the slow-rotation case, but the case with more rapid rotation won’t behave very differently from the results in the Merlis and Schneider paper I cite in the ApJL piece. Generally speaking, as you increase rotation you reduce the day-night difference because the surface has less time to cool down. But also, a more rapidly rotating atmosphere can support larger temperature gradients in principle. But, in actuality the day/night contrast still stays pretty small, because you get atmospheric jets which carry heat around. There are some interesting unresolved questions regarding the behavior of the north/south temperature gradient as a function of rotation, though. –raypierre]

  4. 104
    PHG says:


    Just for information, generally wind turbines do not curtail their power output until the temperature drops below -10 deg C, unless they are equipped with a cold weather package that allows for lower temperature operation. Power output is ramped down from maximum output at -10 to standstill at -20 deg C.

    Blade icing is a separate issue, normally it’s a concern only in coastal areas with high humidity. Seems like it was too cold for that to be a factor but I could be wrong,

  5. 105
    Hank Roberts says:

    > wind turbines did not all operate at their nameplate power the full time


    Oh, wait:


  6. 106
    Septic Matthew says:

    104, PHG

    Thank you. Having initially overreacted, I think I’ll now wait until I can read a comprehensive account. There are reports of turbines failing, but the whole system from Texas to California, including Utah, is being tested and found, so to speak, wanting. The turbine failures (if real) were a small fraction, not a large fraction, of the 7,000 MW that was out of service.

    There is more interesting good news on solar power in California, which I’ll post tomorrow or later.

  7. 107

    #98–Kensit, thanks for that info. Very interested that Dr. Weaver has served Ball for his lies. I’m wishing him luck; it’s appalling how consequence-free deliberate falsehood has been of late.

    (I’m also interested to see that Dr. Weaver apparently has a new book, Generation Us, coming out this spring.)

  8. 108
    Didactylos says:

    Septic Matthew: Thank you for linking to that supreme display of idiocy by know-nothing weathermen.

    I hope that you know that wind power is nowhere near peak during extreme winds, because the turbine speed has to be limited. Also, the peak rating is just that – peak. Pretending that turbines are supposed to deliver peak output constantly is just ignorant.

    Your mention of the comments is curious, since I only see vitriolic ignorance there.

  9. 109
    David B. Benson says:

    For those intereted in some technical detail of wind turbines in Europe.

    IEA Wind Power Study

  10. 110
    Ken Fabos says:

    Edward Greisch @19 – could be the aliens got annihilated by excess O2 when pesky photosynthetics that release that toxic, combustion promoting gas spread out of control. Or too much CO2 got sucked out of the atmosphere into carbon sinks to become (eventually) carbonate rock, coal and oil and that sent their world into a perpetual ice age? The conditions they thrived on could have changed radically but those conditions are not necessarily based on atmospheric conditions like ours.

    Isn’t our problem that the conditions we’ve grown and thrived with are facing radical change?

  11. 111
    David B. Benson says:

    Tangentially related to the CO2/H2O back radiation question, during LGM both CO2 concentrations and temperatures were lower. This graphic
    certainly suggests that, by in large, the world was a rather dryier place than it is now.

    But it was not too dry for proto-agriculture. The Jomons appear to have begun ca. 14,000 years and and recently a new dig in northrn Jordan strongly supports the idea of proto-agriculture there before ca. 16,000 years ago.

  12. 112
    Hank Roberts says:

    Apropos the term “back-radiation” the following search turns it up from Revelle’s 1957 _Tellus_ article (link will break at the double-quotes so copy and paste it). All I see is the bit Google Scholar quotes.

    I wonder how his estimate of a “ten year” CO2 lifetime determined how the state of things looked to him and how it might have been different if he’d had a better idea how much of the CO2 then in the atmosphere was already there from fossil fuel.

  13. 113
    J-Chapman says:

    It would be nice if there were a way to search articles at in a way that excluded the comments. I have been trying to find out if there have been any articles about the Permian extinction, and wading through lots and lots of comment posts. . .


  14. 114
    Aaron Lewis says:

    I look at “Still Hope for Arctic Sea Ice” ( ) and I cannot quite understand the animation of Arctic sea ice over the last 30 days. ( )

    Any suggestions on how we could have the ice area changes in the animation, when “the models” say it is a long way even to summer breakup? To me, the variance in the Barents and Kara sea’s sea ice area suggest the models may not include all factors.

  15. 115
    Fred Moolten says:

    Raypierre (87) – I’ve read Judy Curry’s radiative transfer pieces on her blog, including her reference to your Physics Today article, which she praises. I’ve had some questions about specific points, but I’m unaware of any egregiously wrong representation of the subject in her descriptions. In fact, they tend to conform well to most mainstream descriptions of radiative transfer that I’ve seen, including those in your new book.

    I wonder whether you shouldn’t revisit your generalization about her knowledge in this area. If you disagree with specific points, you should mention them, but unless you continue to judge her understanding to be seriously deficient in general, I would recommend that you modify your statement to one that is less perjorative.

    [Response: You can recommend all you want, but I’m not going to be less pejorative until Judy loses the habit of making a big noise first and only learning the subject matter afterwards. But I’m glad she likes the PT article; any common ground is a step forward. –raypierre]

    [Response: May I please add, that while it is reasonable to talk about ‘mainstream views’ on climate variability (for example), there is no ‘mainstream’ understanding of radiative transfer. There is very simply a correct one. I may not be up to speed on the details the way Ray is, but I am unaware of any scientific ‘alternatives’ in the known physics.–eric]

    [Response: I’ll also add that I’ve given my opinion on Judy Curry’s level of understanding of climate and you can take it or leave it. It’s not a high priority for me to spend my time giving a detailed scorecard of what Judy understands and what she doesn’t and what she initially didn’t understand but after a while was dragged kicking and streaming into understanding. I have other things I need to be doing. If you want me to provide that level of evaluation, you should persuade Judy to enroll in one of my courses. It’s the sort of thing students pay tuition for, you know. You’re lecturing the wrong person, Fred. –raypierre ]

  16. 116


    I’m a bit confused on your references to turbulent exchange. On a molecular level (only), how does heat get transferred from the surface to the atmosphere, or vice versa, except by conduction? I’m interpreting “turbulent exchange” to effectively mean the movement of large bodies of air, due to various external factors (temperature differentials, planetary rotation, Coriolis effect, etc.). Or am I misunderstanding?

    [Response: Heat is transferred by conduction to a very, very thin layer of atmospheric molecules in contact with the surface, but if you had to rely on molecular diffusion to carry this heat up to the rest of the atmosphere it would take hugely long. Conduction essentially instantaneously resets the temperature of the diffusive sublayer to the temperature of the ground, but then you have to rely on turbulence to carry the energy the rest of the way into the atmosphere. Good question, though. –raypierre]

  17. 117
    Chris Colose says:

    Bob, there’s plenty of mechanically driven or buoyancy-driven (convection) turbulent exchanges that help regulate the surface energy budget through the transport of heat/moisture, and turbulent eddies also maintain momentum balance. If the boundary layer is statically unstable, something known as flux Richardson number is negative and turbulence is sustained by convection, a critical part of atmospheres which let in a lot of sunlight to heat the ground (or gas planets heated by interior heat release).

    By the way, I know your hypothetical considers only a transparent atmosphere, but N2 in general can be a very effective greenhouse gas. It’s not on Earth (but still contributes to pressure broadening) but it does have collisional continua that can be important and may dominate the greenhouse effect for colder and denser atmospheres. O2 may also not be completely unimportant since it lacks an electric dipole but has a permanent magnetic dipole moment, giving rise to a few rotational absorption bands.

  18. 118
    Sou says:

    @JChapman #113, the zvon link at the top of the right hand sidebar is probably the best way to search for articles on realclimate, using the keyword search.

    I’ve searched for permian using both zvon and google and it looks to me that RC has not published an article on this event. There is a Wikipedia article and lots of papers in Google Scholar if you want to research the topic. (Someone please correct me if I’m wrong.)

  19. 119
    Fred Moolten says:

    Re 87 and 115 –
    “You’re lecturing the wrong person, Fred” (Raypierre 115)

    No, I’m lecturing the right person, although it wasn’t intended as a lecture. I’m addressing a person who is justifiably acknowledged to be one of the true experts in the field – someone whose comments should make a perceptible difference in the conclusions others draw about climate science principles. That impact depends on credibility, and if credibility is sacrificed by issuing statements based on inadequate information, the impact is lessened, even if the statements are about another person rather than a radiative transfer equation. I have the impression from your comments, Raypierre, that your claim that Judy Curry’s understanding of radiative transfer is highly deficient (stated in the present tense) is not based on your own knowledge of her current understanding. If that’s true, she deserves better, and her history is irrelevant. I often cite you in trying to make a strong case on climate science issues. I want your credentials for objectivity to remain as impeccable as your credentials for expertise. If it were someone else making unfair accusations, I wouldn’t have bothered.

    Eric – I’m not sure why you interjected a comment. It misrepresented my point. I did not refer to mainstream radiative transfer views but to mainstream “descriptions”. Descriptions are not intended as opinions but as statements of fact, and the mainstream descriptions are factually correct.

    I’ve said all I wanted on these points. From now on, I’ll keep my peace.

    [Response: Fred, I think Ray made his point pretty clear. As for my interjection, you make a fair enough distinction. Still, I wanted to make sure there was no ambiguity here. This radiative transfer stuff actually is settled. Curry’s attempts to ‘discuss’ it provide no clarity — or learning opportunity — that I can discern.–eric]

  20. 120
    Chris Dudley says:


    Back at the end of the last roundup, we got to the point where carbon dioxide could not maintain a high surface temperature for long enough (owing to weathering of silicate rocks) for enough hydrogen to escape to space from a high water vapor mixing ratio stratosphere for the Earth’s oceans to be eliminated. The time to eliminate the oceans would be over 100 million years and weathering works over the million year timescale.

    Looking closely at fig. 5 of Kasting (1988) it appears as though the atmosphere may be unsaturated up to 25 km or so for the 340 K surface temperature curve above which it follows the moist adiabatic lapse rate.

    It strikes me that for a raindrop formed in the saturated portion of the atmosphere above 25 km, a fall through 25 km of unsaturated air may cause it to evaporate. Such things can happen even with the much lower cloud decks of today.

    Without rain, or indeed freeze/thaw cycles at high elevations, the weathering rate of silicate rock may be slower than at present or in the past. If so, vulcanism may maintain the atmospheric carbon dioxide content up around 3000 ppm, as proposed by Hansen, for much longer than we would normally expect.

    A one dimensional model may not be adequate to assess the likelihood of rain falling to the surface anywhere but it is intriguing that we might be left with only a bit of ever receding tidal sloshing to expose fresh calcium ions and deliver them to the wet chemistry needed for limestone formation.

    Not a dead certainty at this point in my mind, but perhaps a deadly uncertainty worth a more detailed look?

    [Response: Like (almost) all such studies to date, Kasting’s calculation is done using a radiative convective model, which lacks any large-scale dynamics. Some parameterized convection models (like Emanuel’s) can generate unsaturation through microphysical processes, but lacking large scale dynamics there can be no real prediction of unsaturation. Any subsaturation in a model like Kasting’s would be put in there by fiat, not because it is right. In any event, in the moist runaway, there is a liquid ocean at the surface, which means there is a dynamic equilibrium between evaporation and precipitation reaching the surface — otherwise the water in the atmosphere would either be increasing or decreasing until equilibrium is achieved. This is not really any different from the Earth’s atmosphere, just hotter. Most of the Earth’s atmosphere is substantially undersaturated, yet rain reaches the ground and returns to the ocean whence it came. In a hot runaway, silicate weathering would proceed much more quickly even for fixed rainfall rate, because of the exponential increase of reaction rates with temperature. I am quite sure this would drive CO2 to low levels in a moist runaway, once silicate weathering has time to equilibrate. I discussed this in an AGU talk some years back, and some of that got into the discussion of hot silicate weathering in Chapter 8. But note that in the moist runaway in Kasting’s calculation, the temperature isn’t high primarily because there’s a lot of CO2 around. The temperature is high because the solar absorption is high. If you added 5000 GT of carbon as CO2 to Kasting’s atmosphere, it would make hardly a blip in the temperature. –raypierre]

  21. 121
    Hank Roberts says:

    > Curry’s attempts to ‘discuss’ it provide no clarity

    JC expresses the hope people understand some basics, but encourages people to go on at length — and her participants, mostly people who don’t understand the material, do go on at length expounding their notions. It’s hard to find any separation between the science and the “etc.”

    I’d have hoped for something from JC at least as clear as Roy Spencer’s recent efforts. But looking back there are quite a few topics full of people’s various odd notions about how the world works. And it’s stuff that’s not helping anyone understand the basic physics.

    There’s a difference between knowing something and being able to teach it or even lead a discussion away from people’s mistakes. Any leadership in teaching the matarial has not been apparent there. It seems to me she’s been trying to win the trust of people by not challenging them when they’re wrong. Not an approach that works, I’d say.

    Posting an actual academic lesson or two, with reading and questions and exercises, would be a useful approach. Others do that successfully. But it requires deciding to teach rather than just host a conversation.

  22. 122
    Chris Colose says:

    I don’t want to get into a debate about Judith Curry and mainstream science so I’m just going to post this, but in an effort to be fair I must point out that she has never been challenging “settled” radiative physics concepts like the existence of back-radiation, Stefan-Boltzmann law, the existence of a greenhouse effect, etc. In fact she has been quite vocal against such people who raise these sorts of objections. Like Eric, I don’t see much point in opening up discussion threads about a book that claims the greenhouse effect is not real, but that’s her choice.

    That said, she has challenged a number of implications that stem from radiative transfer or thermodynamics, such as the “no-feedback climate sensitivty”. She’s also repeatedly misunderstood the details of detection and attribution, made a number of vague and unsupported attacks on her colleagues in climate science, etc. My feeling is that she has just played wolf too many times. I agree with Fred about Judith and back-radiation, but I also agree that keeping tabs on what she’s saying about every topic is not extremely worthwhile anymore.

  23. 123
    dhogaza says:

    Fred Moolten:

    No, I’m lecturing the right person, although it wasn’t intended as a lecture. I’m addressing a person who is justifiably acknowledged to be one of the true experts in the field – someone whose comments should make a perceptible difference in the conclusions others draw about climate science principles. That impact depends on credibility, and if credibility is sacrificed by issuing statements based on inadequate information, the impact is lessened, even if the statements are about another person rather than a radiative transfer equation

    So Judith’s given a free pass for screwing up radiative physics, while raypierre is declared to be a bad representative of science because he points out that Judith’s screwed up, but isn’t willing to give her an undergraduate-level education in the subject for free, on his spare time.

    Does that about sum it up?

    What a sad state the world is in …

  24. 124
    dhogaza says:

    That impact depends on credibility, and if credibility is sacrificed by issuing statements based on inadequate information

    And, Fred, assuming that he’s wrong about Judith, how does this affect his credibility regarding physics?


    (for the record, raypierre’s right on regarding judith, but Moolten’s statements regarding transference of credibility is just stupid. He’d sink Newton, too …)

  25. 125
    Edward Greisch says:

    Raypierre: “Resources tab on the CUP web site. That’s open-access, as is the courseware on my own site”

    URLs please?

    [Response: Sorry, it takes a few extra tens of seconds to insert links, and to give me more time to answer questions here I often skip that in the assumption that people know where the basic resources are by now. My own book site is here and that also contains a link to the Cambridge U. Press site which has the figures. I’ll eventually put a copy of the figures on my own site also, but haven’t gotten around to it yet. The figures are provided gratis by Cambridge for the convenience of people using them in lectures and presentations. -raypierre]

  26. 126
    JiminMpls says:

    #89 What Gavin really wrote in response to Lisbon invitation (from Tallbloke’s blog)

    Here is Gavin’s response:

    “I’m a little confused at what conflict you feel you are going to be addressing? The fundamental conflict is of what (if anything) we should do about greenhouse gas emissions (and other assorted pollutants), not what the weather was like 1000 years ago. Your proposed restriction against policy discussion removes the whole point. None of the seemingly important ‘conflicts’ that are *perceived* in the science are ‘conflicts’ in any real sense within the scientific community, rather they are proxy arguments for political positions. No ‘conflict resolution’ is possible between the science community who are focussed on increasing understanding, and people who are picking through the scientific evidence for cherries they can pick to support a pre-defined policy position.”

    You go, Gavin! Again, I believe a libel suit is in order here.

  27. 127
    JiminMpls says:

    Totally OT – Where’s Barton? He hasn’t posted in quite some time. Is he OK?

  28. 128
    ccpo says:

    Fred Moolten says:
    3 Feb 2011 at 10:57 AM

    A subject that perhaps deserves more attention than often awarded is the extent to which future climate change is dependent on the availability of easily extractable fossil fuel reserves. Coal is often estimated at about 900 Gtons, and oil plus gas at probably a smaller figure.

    It’s moot except in discussion of apocalyptic scenarios. 1. We’re already over budget, so *any* more is just adding to the problem. 2. We are already seeing all the problems we feared at even higher CO2 concentrations, so how much worse can it get, except to see them fully realized? 3. Recent research (Hansen, et al., I believe) indicates Greenland can destabilize at 400 ppm, and we will hit that in a few years. 4. Just ten percent of the permafrost melting will give us another 80 ppm or so, then add in the continued deforestation and melting sea floor clathrates… we’re looking at over 500, and closer to 600 ppm already.

    This argument that FF reserves are too low to be dangerous is not logical.

  29. 129
    radun says:

    If unforced variation = natural variation, then it might not be always possible to separate coincidence from acquiescence as the case may be in here:

    [Response: There are also natural forcings – solar, volcanic, orbital etc, so the magnitude of internal variability (aka unforced variations), cannot be simply defined from the observed record. – gavin]

  30. 130
    Ray Ladbury says:

    Come on. Judy has committed some appalling blunders. Moreover, I find that I’ve never really learned anything from her expositions. All I can say is that there are much better and reliable sources on the science. Judy has not published anything relevant to climate science in a decade. That’s not a characteristic I look for when I’m looking for someone who can explain the science.

  31. 131


    I have one quick separate question. I wound up in a debate where I was trying to explain something tangentially related to what was previously discussed… Most people were getting all tangled up in the idea that CO2 “shoots IR” around (up, down, sideways) and that most of it should therefore escape into space. I tried to point out that in most of the troposphere (until one gets up high enough), density is such that before absorbed IR energy can be emitted, the energy is instead transferred through collisions to O2/N2 (as translational energy), which is then unable to effectively radiate the energy away (in relevant amounts and timescales) due to the geometry of those molecules. This “frees” a CO2 molecule to absorb (and then transfer) more IR, while heating the atmosphere around it.

    The counter argument was that all bodies must radiate, and since O2/N2 make up 99% of the atmosphere, then even if they radiate slowly/weakly, their contribution would still overwhelm that of the CO2 in radiating away heat. “Obviously CO2 plays no part in heating or cooling the atmosphere” was their solid conclusion.

    My problem came from the fact that I could not find any hard numbers on this to prove the counter point (that O2/N2 radiate too slowly/weakly to make any difference, even as 99% of the atmosphere). I could show that the band in which they radiate is narrow, but could not prove that the energy released by the amount of O2/N2 in the atmosphere was still minuscule in comparison to CO2, H2O and other greenhouse gases. I suspect that the O2/N2 (and Ar) contribution is so very small (and accepted) that no one has even bothered to document it.

    But to my question: Are there any numbers (observations or calculations) available on the total amount of energy ultimately radiated to space by each component of the atmosphere, per unit time? Alternately, are there numbers available simply at the molecular level, to show the total expected energy emission, per mole per unit time for each of the gases at normal atmospheric temperatures (and from which, obviously, I could extend to apply to the total atmosphere)?

    [It only just hit me, too, that I could have argued that even if O2/N2 emit enough to matter, they are still constrained by the same issues as CO2, i.e. collisions and re-absorption in the denser parts of the atmosphere. But this would have been dodging the main point, anyway.]

    [Response: I love these questions. Regarding the collisional de-excitation of CO2 states, I do have a paragraph in the Physics Today article addressing some of those issues, with a few numbers in. I would have loved to have rambled on about that for another page or two, but I had to keep the article to 6 pages total. The answer to O2/N2 opacity is easy though, since the infrared opacity of these gases was first measured by Tyndall, and has been repeatedly studied by spectroscopists ever since. The main source of IR opacity for diatomic homoatomic molecules like these is collision-induced absorption, but the effect is so weak for Earthlike atmospheric pressure that the IR opacity of these gases in the Earth’s atmosphere is completely negligible despite the mass. Collision induced abosrption for N2 and H2 has been very well studied for planetary purposes, and you can find a link to a site that has tables in the Data section of my book site. There is also a graph of the N2-N2 absorption cross section in Chapter 4, based on Courtin’s data. For atmospheres as dense and massive as Titan’s the IR opacity of N2 is important, but for Earth you can bang in the numbers and find it is negligible. I don’t have up-to-date numbers for the O2-O2 collisional absorption handy, since it’s unimportant for Earth radiative transfer and planetary people don’t care much about it because it’s hard to think of any way to accumulate an atmosphere with, say, 10 bars of O2 at 95K in it. –raypierre]

  32. 132
    Hank Roberts says:

    > Edward Greisch says:
    >> Raypierre: “Resources tab on the CUP web site. That’s
    >> open-access, as is the courseware on my own site”
    > URLs please?

    Edward, see the right hand columnn on every page here? links to sources and citations from all the RC authors: click on Contributor Bio's — find the name on the list there; click on that; follow.

  33. 133
    Adam R. says:

    Ray Ladbury @ 130:
    “Judy has committed some appalling blunders.”

    Which, to my mind, are the least of her sins against science. Broadly accusing her colleagues of corruption and malfeasance places her firmly among the persistent bad actors in the denier world.

    Why should any scientist who has been tarred with her libelous brush, even by association, attempt to engage with her in good faith?

  34. 134
    Chris Dudley says:

    Raypierre (#120),

    Kasting did go to quite a bit of trouble to understand the lapse rate in his model. There is an appendix on the details. I was thinking though that large hail should make it to the surface and with a higher terminal velocity than rain drops, would have quite an impact from a 25 km fall. That might expose fresh surfaces.

    [Response: You’re not paying attention. First, it’s the relative humidity profile we’re talking about, not the lapse rate. Second, you ignored the argument I gave you that the rain MUST reach the surface, otherwise the hydrological cycle would be out of equilibrium; a subsaturated low level atmosphere will always create evaporation, and if this isn’t balanced by rain reaching the surface the water content of the atmosphere grows. In a true runaway, the water vapor content of the atmosphere indeed increases until there are no oceans left. In a moist runaway (by definition) you reach an equilibrium before that point is reached. –raypierre]

    Martin Rees was very sure that the collision of pairs of neutron stars produce some gamma-ray bursts. Models were not good enough to show it. He just knew it. The experiment to check that seems to be very sensitive gravitational wave detection. Those may or may not be available during his lifetime. So far, evidence for neutron star black hole mergers as the origin of short gamma-ray bursts is available.

    Hansen has expressed a similar sentiment at the end of his chapter. Models aren’t good enough but he feels sure.

    I don’t think helium rain makes it to the core of Saturn. You’re pretty sure that rain on Earth must reach the surface. But, we are now in the same position as Rees and Hansen except with more time, if not more brain power, to investigate the question.

    The world desert alternative gives another 3000 GT of carbon from soil so blips might be adding to something.

    [Response: I’m not sure what you’re getting at here, but if you want the last word in this discussion, you can have it. –raypierre]

  35. 135
    Hank Roberts says:

    > 89, 126
    Jiminmpls, you quote (and the guy may have only seen) one of two paragraphs. It’s always better to point to your source rather than copypaste from it so people can find the context and follow the thread. Do that and you’ll eventually get to Gavin’s full email response:

  36. 136
    Ray Ladbury says:

    Bob (Sphaerica), Huh? I think that where you are getting wrapped around the axle is when you say categorically that “all bodies must radiate”. They will radiate, but they can only radiate at energies that correspond to an energy difference in the molecule or atom. N2 and O2 have no absorption/emission lines in the IR. Therefore they do not radiate significantly at terrestrial temperatures.

    However your interlocutors are even more confused. In an atmosphere that cools as you go up, any absorber/emitter will absorb more than it emits, for the simple reason that the radiation field is not in equilibrium with the matter. Your correspondents do not understand blackbody radiation, which is a simple consequence of a photon gas in equilibrium with surrounding (perfectly absorbing/emitting) matter. When the absorber/emitter is not perfect, the emission spectrum will look like a slice out of the blackbody spectrum over the spectral range where it can emit/absorb.

  37. 137
    J Bowers says:

    Dr Paul Williams makes a generous offer at the Guardian, which might be of interest to those who are into modelling (if you’re not already aware of it).

    You are absolutely right that this is a very general algorithm, which is applicable to more than just weather and climate models. I’m happy to send you (and anyone else) PDFs of this new study, as well as a couple of related papers, if you want the gory details. Contact details are on my website, which is linked from the article.

    How better time travel will improve climate modelling

    The addition of just a couple of lines of code to the model led to the five-day weather forecast being as accurate as the old four-day forecast. That would mean 24 hours more notice of what’s on the way. And to get climate models right, you need to first get the weather right, so good news there too.

    The fact that the tweak is so concise bodes well for its uptake, as it doesn’t need modellers to reengineer their millions of lines of code. It is now being tested in over 50 more models.

  38. 138
    Ray Ladbury says:

    Adam R. says, “Why should any scientist who has been tarred with her libelous brush, even by association, attempt to engage with her in good faith?”

    Scientists are by and large a forgiving bunch. They will tend to remain on good terms with any other scientist who is doing good science even if they suspect their brains of resembling creatures of the Antediluvian. I have colleagues (a very few, I would add) I would not trust further than I could throw them on a steep upslope that I make a point of discussing matters with at conferences, because they have an interesting and thought provoking perspective…even if I feel I must wash afterwards. A scientist who rashly draws conclusions without understanding the facts, though, tends to be rather lonely at conferences. They may be perfectly nice, even bright, and it may be nothing personal. Conferences are busy times. Scientists are busy people. Oh well, at least Judy has the adulation of the denialosphere.

  39. 139
    Ray Ladbury says:

    Chris Colose @122 says, ” don’t want to get into a debate about Judith Curry and mainstream science so I’m just going to post this, but in an effort to be fair I must point out that she has never been challenging “settled” radiative physics concepts like the existence of back-radiation, Stefan-Boltzmann law, the existence of a greenhouse effect, etc.”

    So could we summarize Judy’s position as being uncomfortable with anything that has happened since, oh, 1900?

  40. 140
    Judith Curry says:

    Re # 87

    Ray, since you and your readers seem interested in radiative transfer in the wintertime high latitudes, you might want to read some of my papers on the subject (note this was the subject of my Ph.D. thesis):

    Curry, J.A., 1983: On the formation of continental Polar air. J. Atmos. Sci., 40, 2278-2292.

    Herman, G.F. and J.A. Curry, 1984: Observational and theoretical studies of solar radiation in Arctic stratus clouds. J. Clim. Appl. Met., 23, 5-24.

    Curry, J.A. and G.F. Herman, 1985: Relationships between large-scale heat and moisture budgets and the occurrence of Arcticstratus clouds. Mon. Wea. Rev., 113, 1441-1457.

    Curry, J.A., 1986: Interactions among turbulence, radiation and microphysics in Arctic stratus clouds. J. Atmos. Sci., 43, 90-106.

    Curry, J.A., 1987: The contribution of radiative cooling to the formation of cold-core anticyclones. J. Atmos. Sci., 44, 2575-2592.

    Curry, J.A. and E.E. Ebert, 1990: Sensitivity of the thickness of Arctic sea ice to the optical properties of clouds. Ann. Glac., 14, 43-46.

    Curry, J.A. and E.E. Ebert, 1992: Annual cycle of radiative fluxes over the Arctic ocean: Sensitivity to cloud optical properties. J. Climate, 5, 1267-1280.

    Curry, J.A., J. Schramm and E.E. Ebert, 1993: Impact of clouds on the surface radiation budget of the Arctic Ocean. Meteor. and Atmos. Phys, 57, 197-217.

    Curry, J.A., D. Randall, and W.B. Rossow, and J.L. Schramm, 1996: Overview of arctic cloud and radiation characteristics. J. Clim., 9, 1731-1764.

    Pinto, J.O., J.A. Curry, and C.W. Fairall, 1997: Radiative characteristics of the Arctic atmosphere during spring as inferred from ground-based measurements. J. Geophys. Res., 102, 6941-6952.

    Pinto, J.O., J.A. Curry, and A.H. Lynch, 1999: Modeling clouds and radiation for the November 1997 period of SHEBA using a column climate model. J. Geophys. Res., 104, 6661-6678.

    Curry, J.A., P. Hobbs, M. King, D. Randall, P. Minnis, et al.. 2000: FIRE Arctic Clouds Experiment. Bull. Amer. Meteorol. Soc., 81, 5-30.

    Benner, T , J.A. Curry, and J.O. Pinto, 2001: Radiative transfer in the summertime Arctic. J. Geophys. Res., 106, 15173-15184.

    When I make a public statement about what a scientist does or does not know, I make a point of actually reading what that scientist has to say on the subject, rather than what other people say about that scientist on blogs.

    Judith Curry

  41. 141
    Didactylos says:

    “When I make a public statement about what a scientist does or does not know, I make a point of actually reading what that scientist has to say on the subject, rather than what other people say about that scientist on blogs.”

    And she said it with absolutely no sense of irony, too!

  42. 142
    Hank Roberts says:

    A recent reply by JC over there gives a feel for what’s been happening:

    ( )

    \… he can probably get this published in E&E, but certainly not in any scientific journal of any repute or credibility.

    Given your complete failure to understand all this, I do not see any point to engaging with you further on any topic related to the science of the greenhouse effect. Over the past year, I have very patiently pointed out to you many problems with the ideas and theories you are promoting. By your irrationality on this subject, you are isolating yourself even from skeptics like Monckton…..\

    \… the insights themselves prevail. Even if the establishment shoots the messenger, so long as the message is valid it will work its way into the heart of the enemy’s camp….\ — Peter Watts

  43. 143
    Brian Dodge says:

    Sad news –

    “Professor emer. Dr. Phil. Willi Dansgaard passed away Saturday, January 8, 2011 at the age of 88 years.”
    “[His] chance discovery in 1952 and 12 years of systematic work resulted in a scientific description on how it was possible to use the content of the hydrogen isotope Deuterium and the isotope O-18 in natural precipitation to determine the temperature of the precipitating clouds.”

    but his work is a reminder of how broad the shoulders are of the giants we stand on.

    The O18-abundance in fresh water – Dansgaard (1954), “Fresh water of various origins as distinct from ocean water shows great variations in O18-abundance. Proceeding from the temperate towards the colder climates a considerable decrease is noticeable.”

    Stable isotopes in precipitation, W Dansgaard – Tellus, 1964 (google scholar reports 2378 cites)

    Evidence for general instability of past climate from a 250-kyr ice-core record – Dansgaard et al. (1993) “Recent results from two ice cores drilled in central Greenland have revealed large, abrupt climate changes of at least regional extent during the late stages of the last glaciation, suggesting that climate in the North Atlantic region is able to reorganize itself rapidly, perhaps even within a few decades.”,
    his work as a climatologist has been singularly influential.


  44. 144
    Septic Matthew says:

    108, didactylos: Your mention of the comments is curious, since I only see vitriolic ignorance there.

    I hear you. The “good” comments were rather far down the list, and they were a minority.

  45. 145
    Adam R. says:

    When I make a public statement about what a scientist does or does not know, I make a point of actually reading what that scientist has to say on the subject, rather than what other people say about that scientist on blogs.

    Judith Curry

    Good grief. This from the woman who said:

    “Once the UNFCCC treaty was in place, there was pressure on the IPCC to back this up with science. Hence the “discernible” in the SAR. Ben Santer has taken huge heat for that, but look at where the pressure was coming from. The whole UNFCCC treaty wouldn’t make sense unless there was at least “discernible” evidence that this was actually happening.

    …and then:
    I do not have any knowledge of this situation beyond what is reported in the standard sources. This issue has been widely discussed and disputed. There is no particular reason to rehash it here, i brought it up as a key issue in the history of the IPCC and the debate surrounding it.”

  46. 146
    Septic Matthew says:

    105, Hank Roberts: > wind turbines did not all operate at their nameplate power the full time


    do you disagree with my suggestion that providing 7% of available power was a good thing? Everybody knows that they only provide on average about 35% of nameplate power, but their over all performance during the crisis was respectable, about equal (according to one of the links I provided) to last year. You don’t disagree with that, I hope.

  47. 147
    R.Gates says:

    Re: Post #87: As the one who originally posted this, and sparked a bit of discussion related to radiative transfer, let me just say this. There are many non-professional scientists who frequent the more popular climate-related blogs who are either directly in policy making roles, or are staff members working for policymakers and have been tasked with keeping up with the issue global climate change. So in addition to direct briefings by science advisory boards and reports such as the IPCC, these blogs are beginning to fill a more and more essential role for allowing one to keep abreast of issues through these kinds of important background discussions. Blogs of course have their obvious limits, but they also have advantages that other sorts of briefings and reports don’t. Yes, it must get very tiresome, tedious, and frustrating for scientists to see the nonsense that is posted on these blogs, but that is part of the new way the science is being communicated. For example, if both Dr. Curry and Dr. Pierrehumbert were testifying before a panel in Washington, and stated different positions on the same issue, then at some point behind closed doors a policymaker is going to have to make sense of those disagreements and ultimately set policy based on how well they (and their all important staff) have been able to “read between the lines” of differing testimony given by two PhD’s. I would maintain, that this blog, Dr. Curry’s blog, and even such blogs as WUWT can help to supply a bit of the background necessary to “read between the lines” in differences of opinion. The majority of those setting climate related policy will hardly be able to understand the complexities of radiative transfer, but they’d better darn well trust that they (and their all important staff) have understood enough of the the science, and enough of the uncertainties (and when there are truly uncertainties) to set reasonable and effective climate-related policy.

  48. 148
    Snapple says:

    In an article I read in a blog called the Examiner, Judith Curry criticized Dr. Mann’s role in the UN because he was young, inexperienced, and had only recently received a PhD. Her tone was was really patronizing. She didn’t say why the hockey stick was wrong. She even mistakenly identified Dr. Mann’s institution as U. Mass. Dr. Curry just sounded jealous to me of a younger more gifted scientist. Dr. Mann earned several advanced degrees before his PhD, and great scientists often do great work when they are relatively young. Perhaps the more senior UN scientists recognized Dr. Mann’s exceptional abilities and understood how his research could make climate change clear to policy-makers.

    Dr. Curry did not seem aware of the fact that many other scientists have subsequently demonstrated this hockey stick graph in their own work.

    She tries to pass herself off as some kind of expert, but she didn’t make any scientific points. She was just really catty.

  49. 149

    136, Ray,

    Yes, no, I know… that is, I wasn’t the one saying that all bodies must radiate, they were. And admittedly O2/N2 do radiate some in the IR, due to rotational energies (I think), but in such narrow, infrequent, and low energy bands as to be negligible. My problem was coming up with documented numbers to refute their broad brush, ill-conceived claims.

    [Response: Sorry, I didn’t mean to give the impression that I thought you had this misconception yourself. I was just trying to provided the arguments you would need to address the issues raised by your friends. The simple answer is just that the infrared opacities of N2 and O2 have been measured, and they are too small to make any significant difference to Earth’s atmosphere. Then, if you want to explain WHY the opacities are small, the answer is that the transitions in N2 and O2 that have the right energy levels to couple to IR have no dipole moment (just draw the sketch of a diatomic homoatomic molecule being stretched) so they only couple to the electromagnetic field very weakly, through higher moments. Those higher moments aren’t the main source of opacity in dense atmospheres though — in that case it’s the ability of collisions to make a pair of colliding molecules act like a complex molecule for the time they are together. N.B: those latter arguments will only be of use when talking to physicists. –raypierre]

    But the problem they were having (after first completely ignoring the transfer of energy due to collisions, as well as how those factors change with altitude/density) was this idea that “everything must radiate” with a sort of socia1ist equality. A lot of people seem to have a problem understanding that a black body is a conceptual convenience, not a real universal condition.

    I’m the first to admit that I don’t understand everything, and in my advanced years I’m now annoyed to discover that half of learning now involves unlearning what I thought I understood, but didn’t… but it is shocking how many people are very, very confused by so many things, even rather arrogant engineers who think they are beyond being taught or better educated.

    [Response: Nobody understands everything. One of the things I absolutely love about the area I am working in is that there’s ALWAYS something more to learn. The important thing is to be able to know when one is ignorant, and needs to put in time learning something. A lot of people who should know better don’t do this. –raypierre]

    On the flip side, I’m also embarrassed at what I had thought was the great public school and private university education I had received. My own daughter is now in honors chemistry in high school (a mediocre high school, at that) and she’s learning the material far better and in more depth than I ever did.

    [Response: I am also completely in awe of the scientific and mathematical training the top students get in high school these days. –raypierre.]

    Admittedly she has the advantage of that wonderful rarity, a fantastic and engaged teacher, but still, I’m stunned at how much better her education has been in both chem and bio than mine was back in the 70s in high school. It’s just too bad that it only applies to the honors classes, which in turn only hosts 10% of the students, and only half of those are actually understanding and learning what they’re being taught.

  50. 150


    Your site is fantastic. A wealth of real, hard data. It’s been put at the top of my climate bookmarks.

    [Now I’m going to have to buy your book, too, and then build a working time machine so that I have time enough to read it.]

    [Response: Thanks. By the way, the Gruzka and Borysow collision induced absorption data I link on the site is in the funny units beloved of spectroscopists — (1/cm)/amagat**2 . To me amagat sounds like an Irish curse of some sort, but really it’s just a unit of density. In the graphs in my book I convert C.I.A. absorption data into m**2/kg units that make it easier to do path computations (to estimate optical thickness you just multiply by the mass path in kg of gas per m**2 of surface area of the planet). I have that for N2-N2 in the book, but I didn’t include the H2-H2 data there. When I do a second edition, I plan to replace a lot of the discussion of the continua — esp. the CO2 continuum — with the newer stuff from Gruzka and Borysow. –raypierre]