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The greenhouse effect and the 2nd law of thermodynamics

What the science says...

Select a level... Basic Intermediate

The 2nd law of thermodynamics is consistent with the greenhouse effect which is directly observed.

Climate Myth...

2nd law of thermodynamics contradicts greenhouse theory


"The atmospheric greenhouse effect, an idea that many authors trace back to the traditional works of Fourier 1824, Tyndall 1861, and Arrhenius 1896, and which is still supported in global climatology, essentially describes a fictitious mechanism, in which a planetary atmosphere acts as a heat pump driven by an environment that is radiatively interacting with but radiatively equilibrated to the atmospheric system. According to the second law of thermodynamics such a planetary machine can never exist." (Gerhard Gerlich)


Skeptics sometimes claim that the explanation for global warming contradicts the second law of thermodynamics. But does it? To answer that, first, we need to know how global warming works. Then, we need to know what the second law of thermodynamics is, and how it applies to global warming. Global warming, in a nutshell, works like this:

The sun warms the Earth. The Earth and its atmosphere radiate heat away into space. They radiate most of the heat that is received from the sun, so the average temperature of the Earth stays more or less constant. Greenhouse gases trap some of the escaping heat closer to the Earth's surface, making it harder for it to shed that heat, so the Earth warms up in order to radiate the heat more effectively. So the greenhouse gases make the Earth warmer - like a blanket conserving body heat - and voila, you have global warming. See What is Global Warming and the Greenhouse Effect for a more detailed explanation.

The second law of thermodynamics has been stated in many ways. For us, Rudolf Clausius said it best:

"Heat generally cannot flow spontaneously from a material at lower temperature to a material at higher temperature."

So if you put something hot next to something cold, the hot thing won't get hotter, and the cold thing won't get colder. That's so obvious that it hardly needs a scientist to say it, we know this from our daily lives. If you put an ice-cube into your drink, the drink doesn't boil!

The skeptic tells us that, because the air, including the greenhouse gasses, is cooler than the surface of the Earth, it cannot warm the Earth. If it did, they say, that means heat would have to flow from cold to hot, in apparent violation of the second law of thermodynamics.

So have climate scientists made an elementary mistake? Of course not! The skeptic is ignoring the fact that the Earth is being warmed by the sun, which makes all the difference.

To see why, consider that blanket that keeps you warm. If your skin feels cold, wrapping yourself in a blanket can make you warmer. Why? Because your body is generating heat, and that heat is escaping from your body into the environment. When you wrap yourself in a blanket, the loss of heat is reduced, some is retained at the surface of your body, and you warm up. You get warmer because the heat that your body is generating cannot escape as fast as before.

If you put the blanket on a tailors dummy, which does not generate heat, it will have no effect. The dummy will not spontaneously get warmer. That's obvious too!

Is using a blanket an accurate model for global warming by greenhouse gases? Certainly there are differences in how the heat is created and lost, and our body can produce varying amounts of heat, unlike the near-constant heat we receive from the sun. But as far as the second law of thermodynamics goes, where we are only talking about the flow of heat, the comparison is good. The second law says nothing about how the heat is produced, only about how it flows between things.

To summarise: Heat from the sun warms the Earth, as heat from your body keeps you warm. The Earth loses heat to space, and your body loses heat to the environment. Greenhouse gases slow down the rate of heat-loss from the surface of the Earth, like a blanket that slows down the rate at which your body loses heat. The result is the same in both cases, the surface of the Earth, or of your body, gets warmer.

So global warming does not violate the second law of thermodynamics. And if someone tells you otherwise, just remember that you're a warm human being, and certainly nobody's dummy.

Basic rebuttal written by Tony Wildish

Update July 2015:

Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial


Update October 2017:

Here is a walk-through explanation of the Greenhouse Effect for bunnies, by none other than Eli, over at Rabbit Run.

Last updated on 7 October 2017 by skeptickev. View Archives

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Further reading

  • Most textbooks on climate or atmospheric physics describe the greenhouse effect, and you can easily find these in a university library. Some examples include:
  • The Greenhouse Effect, part of a module on "Cycles of the Earth and Atmosphere" provided for teachers by the University Corporation for Atmospheric Research (UCAR).
  • What is the greenhouse effect?, part of a FAQ provided by the European Environment Agency.



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Comments 1201 to 1250 out of 1415:

  1. I can't believe this thread now is 1200 posts! There is no violation of the second law with the Greenhouse Effect, because it's not about energy going from cold to warm through a conduction process. Does anyone actually think that a re-emitted photon cannot travel from the colder atmosphere toward the warmer surface? How do the photons from the Sun pass through the colder upper atmosphere and reach the warmer surface?
  2. I mean, I can even agree the net effect of additional CO2 could be zero or a wash, but not because of any second law violation. This is silly.
  3. RW1, you have a lot of posts on this thread and are no less culpable for its length that anyone else who has posted on it. The thread has seen little else than trolling and obfuscation, the worst example being that of Damorbel (see post #915, p. 19). Fred Staples and TOP's latest examples are not much better on substance. No need to add to it.
  4. 1201, RW1,
    Does anyone actually think that a re-emitted photon cannot travel from the colder atmosphere toward the warmer surface?
    Believe it or not, yes. Read the comments to see not only how many people believe it, but how adamant they are in sticking to their misconceptions in post after laborious post. They refuse to accept that there may be things that they misunderstand, and that they would be better served trying honestly and faithfully to find the flaws in their own understanding rather than to assume that they are correct and everyone else is wrong — including thousands and thousands of scientists and the half a dozen people here who are simply trying to help them to get things straight. Too, while the 2nd Law concepts seem basic and inarguable to you and I, climate science is rife with people who perhaps get past that hurdle, but at one point or another develop a disconnect and freeze right there, unable to get past it by learning the science well enough to see the flaws in their reasoning, correct them, and thus to understand everything far, far better and to be able to move on to the next concept. It's a curious human trait that allows such people to possess more than their fair share of intelligence and education and yet be unable to properly apply it because of some quirk of cognitive dissonance.
  5. @1200 pbjamm At some point the title of this blog got changed. Used to be about G&T's paper on the Falsification of the Greenhouse Effect. Same references. It has just been trimmed down to one quote out of that paper.
  6. TOP: "I am trying real hard to make a reasoned point" I'm not sure about that and even if it is true (one could find several different points you have tried to make, none of which is very impressive in terms of reasoning), that's part of the problem. You believe you have a point to make. I don't see that you have done the work to get to the level of understanding where that would be possible. Engage in serious study and your possible "points to make" will melt like snow under the sunshine of understanding. If I were you, sincere as you claim to be, I'd consider taking a course or two at a nearby college or even online.
  7. @1206 Philippe Well the inability to make a reasoned point goes both ways. I haven't seen a reasoned discussion of the points that G&T made regarding the fundamental physics of RGHE, but rather comments about my own less than perfect grasp of the world, the universe and why taxes go up. Perhaps you can address G&T's claim that the concept of radiative balance wrt RGHE is nonsense. (-Snip-). (-Snip-).

    [DB] Trolling snipped.

  8. TOP, G&T is a rambling diatribe of everything they could think of. I am really having a hard time finding any science in it at all. The only true science would be in section 3, but even that is mostly devoted to arguing against flaws in various greenhouse analogies (who cares?) and other things (like, as if anyone gives 2 [your-pick]s, "An Inconvenient Truth"). I had to get to page 47 before it hit any actual science, and then it did what most amateur attempts do, which is to repeat all of known science as if this is a text book, and they must walk the reader through every single foundation concept. Please help me. Find a statement -- a brief, scientific or mathematical statement, not a rambling load of arrogance -- that you believe sufficiently makes the case that the greenhouse gas effect violates the 2nd law of thermodynamics. Please note that your two quotes from this comment of yours do not represent any sort of argument, but rather just ill-considered whining. There is nothing of substance in the statements. Please identify some scientific or mathematical observation that you believe is demonstrated by G&T and which you are not on your own able to discount or untangle.
  9. 1197, TOP,
    In the Wood (1909) experiment, there was a small discrepancy in how fast the two boxes heated... So I jumped to the conclusion that if that was so...
    As has been explained, the Wood experiment is flawed. You cannot take it to be a model for anything, or make any inference from it. As far as the particular effect you describe, however, Wood himself recognized that particular problem and corrected for it (emphasis mine):
    When exposed to sunlight the temperature rose gradually to 65 oC., the enclosure covered with the salt plate keeping a little ahead of the other, owing to the fact that it transmitted the longer waves from the sun, which were stopped by the glass. In order to eliminate this action the sunlight was first passed through a glass plate. There was now scarcely a difference of one degree between the temperatures of the two enclosures.
    To clarify, all that happened here was that the glass plate blocked incoming IR, and so that box warmed more slowly. One thing Wood got wrong, though, was that the bulk of the IR that was being blocked was not coming from the sun but rather from greenhouse gases in the lower atmosphere (the same IR that you measure when you hold up your hand-held IR thermometer). So at that point it was actually the greenhouse gas effect that was interfering with his ability to prove or disprove the existence of the greenhouse gas effect!
  10. I have one question for those who think the GHE violates the second law: If downward re-emitted photons cannot travel from the colder atmosphere toward the warmer surface, how do the photons from the Sun travel through the colder upper atmosphere and reach the surface? Have any of you detractors of this ever felt the Sun's rays on your skin when you go outside?
  11. RW1: Thank you for pointing that out. It sometimes feels like it's not often that climate science skeptics will so clearly call out basic errors on the part of other skeptics.
  12. #1209 Sphaerica : "As has been explained, the Wood experiment is flawed. You cannot take it to be a model for anything, or make any inference from it." Sorry, I'v not read the all thread, but I used to read Greenhouse was not a good analogy, notably because of Wood's experiment, even here for example in France in this (rather prestigious and totally 'mainstrem') ENS popularization website for teachers and laymen. This 2009 paper seems to replicate similar results, albeit with a more complex experiment, than Wood (who is quoted on 10). (To prevent any fanciful interpretation, the authors precised: "Our results apply only to the interpretation of classroomscale demonstrations; they do not call into question the effects of anthropogenic greenhouse gases on the Earth’s climate or existing models of those phenomena.") So, finally, is there a replication / falsification of Wood's experiment in PR literature? Maybe it has been mentioned previously, but the 1200 posts are discouraging... Thanks for information.
  13. @1212, the 2009 paper is a good catch, and thanks for the h/t. However, it is possible to perform a "classroom" demonstration of the greenhouse effect. To do so you require two sealed boxes, with transparent lids. One should be transparent to IR radiation, while the other should be opaque to IR radiation. Both boxes should be evacuated (contain a vacuum) to prevent convection. Further, there should be a transparent, IR absorbing filter with a low emissivity film on the side away from the lamp to screen out IR radiation equally from both boxes. The low emissivity film is necessary because otherwise the filter will itself radiate IR, which is then not properly controlled for. It may also be necessary to evacuate the space between the "lid" and the filter to avoid convective cooling of the lids with outside air. The experiment could be performed with "lids" consisting of two IR transparent plates with the space between filled with CO2 and Argon (or Nitrogen) respectively, however, I believe the gas would need to be at substantial pressure, or the apparatus very large, to detect a significant effect in this case.
  14. There is nothing to address. G&T do not have a point. They play on words, trying to describe something for what it is not and then attack it. G&T is the ultimate strawman. That you can be fooled by it indicates that my assessment is accurate.
  15. 1212,, The Wood experiment was poorly designed, and due to its flaws it proves nothing one way or the other. SkS will have a post on it (hopefully) soon, as a matter of fact, but for the basic synopsis see my previous comment on this thread. I don't believe the falsification exists in the peer reviewed literature, just because it's so old (and the experiment itself was never peer reviewed, either). Everyone knows that it's wrong. Refuting it would be rather like writing a peer reviewed paper to refute Ptolemaic model of the solar system. It's just not necessary.
  16. @1209 Sphaerica So if what you are saying is true about the blocking of the back radiation was the true reason the glass windowed box in Wood's (1909) experiment had a lower temperature rise rate, then if the boxes were pointed at right angles to the sun, the box with the IR transparent window should also show a higher rate of temperature rise assuming that it started at a lower temperature. After all the CO2 that is radiating this back radiation is all around us. Sorry, I missed the flaw in the Wood experiment. Are you saying that it did not in fact show that real greenhouses work by blocking convection cooling and not radiation trapping? That was what was being tested in the experiment. I have half a mind to try to repeat the experiment using DOE methods. Turns out that rock salt windows are commercially available in optical grades at reasonable prices. Now you made a statement that my IR thermometer was possibly measuring the IR from the RGHE when I pointed it skyward. I did a further experiment with the IR thermometer to see if it was in fact measuring any back radiation from RGHE. It does not. The experiment was simple and I will describe it here: Using the flame of a common household propane torch as a source of IR from a visible flame composed primarily of H2O and CO2 at several thousand degrees F measure the flame temperature by pointing the IR thermometer at the flame 6 inches from the torch nozzle and slowly move the detector down the flame towards the source until the IR thermometer is pointing at the nozzle of the torch. Results: Some small temperature increase over background (75F vs 55F room background) from the flame until reaching the metal nozzle at which point the temperature reading jumped to 400F. Discussion of Results: Either the handheld IR thermometer measures a lower temperature than the actual gas temperature because the IR emitted by the high temperature gases was not in the narrow band specific to the semiconductor device or the emissivity of the high temperature gases was so low that the detector could not pick it up (this instrument not having a correction for emissivity available) and of course remembering that T&G don't believe the term emissivity can be applied to the radiation from gases at all as that applies to black body radiation which is not the radiation coming from a gas (no it isn't a different kind of photon, it is a different kind of geometry). Further refinement of the experiment: An aluminum reflector was placed behind the flame and the temperature measured increased significantly, but still nowhere near the actual flame temperature. Conclusion: The IR thermometer I have is not capable of registering any significant back radiation from the green house effect. We'll leave that to the folks who made muon's graphs. RGG emit IR in a very narrow band and require expensive instruments to detect. My IR thermometer was likely just indicating the low end of it's range when pointed at clear sky and the temperature of the moisture in the clouds when pointed at the bottoms of clouds. Note: The IR handheld did detect the correct temperature of hot water which means it should detect water droplet temperature.
  17. @1214 Philippe G&T don't have a point? Apparently they have some kind of point that needs addressing or this thread wouldn't exist. G&T made the assertion from basic physics that the concept of radiative balance is meaningless. They are well qualified to make this assertion in peer reviewed literature and have published on climate related issues on other topics. It is the assertion that they made regarding the concept of "radiative balance being bad physics" that I would like to see an answer to here. You can't just brush that off by saying they are wrong. And no, muon's graphs don't answer the assertion but are to be interpreted by the physics they assert are true. I'll have to check whether Halpern made a rebuttal to this point in his response to G&T. But I don't remember seeing it.
  18. 1216, TOP,
    Are you saying that it did not in fact show that real greenhouses work by blocking convection cooling and not radiation trapping? That was what was being tested in the experiment.
    No. That is not what was being tested. You misunderstand the experiment. I explained this to you already in comment 1175. [As an important side note, if you are going to demonstrate that you either do not read or completely ignore responses to you, then this conversation is a waste of everyone's time. The tactic of simply repeating the same thing over and over as if your points have not been refuted is common and unacceptable. If you simply missed my response I apologize, but I have no time for games.] The purpose of the experiment was to determine if infrared radiation could be "trapped" and slow the cooling process. To do this, the system attempted to control convection and all other factors so that they would be the same in both environments. The only difference in the two setups should have been the ability to emit IR (which would be blocked in one case). The setup failed in this regard. Convection and other factors were unrecognized, so that they warmed the glass plate and the rock-salt plate equally, causing it to emit IR and creating no difference . I have no idea what "RGHE" is. Please don't define your own acronyms and then use them as if they are common place.
    The IR thermometer I have is not capable of registering any significant back radiation from the green house effect.
    I don't know how in the world you get this. This is very simple. We'll work with an analogy. Everyone is in a crowded gymnasium, trying to get an autograph from someone famous at one end. Thus, most of the people are crowded at that end. There are less people milling around in the middle of the gym and almost no one at the far end. One person there is your friend, who has already gotten his autograph and is waiting for you. You are right next to the person signing autographs. The noise there from all of the people clamoring for autographs is deafening. You turn your ear in the direction of your friend to listen to see if he is calling you. What you hear is an ear-splittling cacophony. Based on your logic, you conclude that your friend is able to speak incoherently and deafeningly with several hundred voices at one time. Lets go back to GHG. The air near the surface is far more dense than the stratosphere. The number of CO2 molecules is far higher. The air near the surface is also far warmer. As such, the amount of IR being emitted by the air around you is far, far greater than the IR being emitted by the stratosphere above, and that IR in turn has layer upon layer of intercepting greenhouse gases between it and you. You have no chance of measuring the IR emissions of the stratosphere from the surface of the earth, because it will be masked by the IR emissions of the entire atmosphere, bottom to top, in between.
  19. 1216, TOP, I asked a simple question in comment 1208 and you ignored it. Again, this discussion goes no where if you simply choose to ignore things that are presented to you. I will not waste my time jumping from point to point and simple repeating the same things over and over. To repeat: G&T spend a lot of time making assertions, but do not support them. Most of their assertions and the vast bulk of their diatribe consists of pointless word games and not science. Please identify some scientific or mathematical observation that you believe is demonstrated by G&T and which you are not on your own able to discount or untangle. Please identify some way in which G&T "prove" that greenhouse gases do not work as the rest of the scientific world understands and accepts.
  20. @1215 Sphaerica I'm going to have to break the rules with the moderator's indulgence (-snip-)

    [DB] This is tedious.  Your entire agenda revolves around presumption (as defined by your repetitive use of the word seems): presumption of posts you have not read nor understood in their entirety, presumption of what other people are saying without clearly asking them, presumption of what the greenhouse effect of greenhouse gases actually is and presumption of just how much leeway you will be given in your prosecution of your agenda.

    An agenda which, in the absence of substantive points by you (and failing to answer the repeated clear questions of others) devolves to wasting everyone's time here.

    Get to the point, clearly and without dissembling, or cease.

  21. 1220, TOP,
    the point being tested in the experiment was that greenhouses function by preventing convection
    No. You misunderstand, and this is why you can't get past the Wood experiment. How in the world could GHG's "block convection"? Scientists know that convection contributes to the behavior of the atmosphere. Why would this factor be ignored? As far as the way a real greenhouse works... that's silliness. Of course GHGs don't work exactly the same way. It's an analogy! It's used to introduce a complex concept to people before getting into the nitty grity. If your issue is that the word "greenhouse" is inappropriate (as with G&T) then you are wasting everybody's time! And please stop saying "RGHE". What the heck is "RGHE?"
  22. @1218 Sphaerica You haven't answered my point. I did read 1175
    First, the purpose of the Wood experiment is not to "determine whether radiation or convection controls the temperature of the air inside the box." The purpose is to determine whether or not in a system where convection is not present radiation alone will have the capacity to control temperature in the boxes.
    In the context of both Wood and G&T the convection was with the bulk outside atmosphere. G&T also made that clear with their discussion of the warming of a car interior with closed windows. Anyone knows that convection will occur inside any closed, gas filled container with a temperature differential and gravity. Of course in such a small box, convection will soon come to a halt as the enclosed gas reaches an even temperature. Your comment is obfuscation and a lack of taking the experiment in the context in which G&T offered it. The term RGHE was not coined by me, I just contracted it from "Radiative GreenHouse Effect". It was coined on this thread by someone else and such contractions are commonly used here. If you don't read the thread as you accuse me of doing, what can I say? G&T also proposed using a different term, "atmospheric greenhouse effect", and low and behold, what do you know, it is the first that phrase that occurs in the abstract quoted as the SoD here. G&T don't support their assertions? Did you read the paper?
  23. Sphaerica, I may have misunderstood you but you appear to say that the purpose of Wood's experiment was to disprove the greenhouse effect. That is not correct. Rather, it was to show that actual greenhouses (made from glass) where warmed by preventing convection rather than by the radiative effects of the glass. As he said in his article:
    "THERE appears to be a widespread belief that the comparatively high temperature produced within a closed space covered with glass, and exposed to solar radiation, results from a transformation of wave-length, that is, that the heat waves from the sun, which are able to penetrate the glass, fall upon the walls of the enclosure and raise its temperature: the heat energy is re-emitted by the walls in the form of much longer waves, which are unable to penetrate the glass, the greenhouse acting as a radiation trap. I have always felt some doubt as to whether this action played any very large part in the elevation of temperature. It appeared much more probable that the part played by the glass was the prevention of the escape of the warm air heated by the ground within the enclosure. If we open the doors of a greenhouse on a cold and windy day, the trapping of radiation appears to lose much of its efficacy. As a matter of fact I am of the opinion that a greenhouse made of a glass transparent to waves of every possible length would show a temperature nearly, if not quite, as high as that observed in a glass house. The transparent screen allows the solar radiation to warm the ground, and the ground in turn warms the air, but only the limited amount within the enclosure. In the "open," the ground is continually brought into contact with cold air by convection currents."
    Wood's experiment does in fact demonstrate exactly this point, ie, that physical greenhouses in fact prevent convection from carrying heat away from the surface, and thereby raise the temperature. However, he goes on to say:
    "Is it therefore necessary to pay attention to trapped radiation in deducing the temperature of a planet as affected by its atmosphere? The solar rays penetrate the atmosphere, warm the ground which in turn warms the atmosphere by contact and by convection currents. The heat received is thus stored up in the atmosphere, remaining there on account of the very low radiating power of a gas. It seems to me very doubtful if the atmosphere is warmed to any great extent by absorbing the radiation from the ground, even under the most favourable conditions. I do not pretent to have gone very deeply into the matter, and publish this note merely to draw attention to the fact that trapped radiation appears to play but a very small part in the actual cases with which we are familiar."
    However, that was not the ostensible purpose of the experiment, and nor does it follow from the results he obtained. Like many a denier since, Wood has simply misinterpreted his own result. What is more, his experiment is clearly irrelevant. The greenhouse effect was deduced by an imbalance between the temperature of the Earth's surface, and the temperature the Earth' surface needed to be to balance the incoming solar energy with outgoing IR radiation. Because the effect is calculated and predicted purely from the physics of radiative transfer, the fact that convection cannot carry energy into space can in no way undermine the theory. So while it is in principle possible to falsify the greenhouse effect, it is not in principle possible to do so using Wood's experimental design, and that is exactly because it allows as a significant method of heat transfer a means (convection) which is precluded in space. (It is in principle possible to refute the greenhouse effect with a similar experiment as described in my 1213, although the performance of such an experiment would bitterly disappoint deniers everywhere.) It follows from this that all discussion of Wood's experiment is a red herring, something you already appreciate. All it shows of relevance is what everybody admits, that the "greenhouse" analogy is inexact. Finally, I understand your frustration with TOP. All he seems to do is waffle on vaguely, misrepresent the opinions of others and never get to any substantive point. I heartily recommend that further discussion of Wood's experiment be declared off topic on this thread, and that TOP be required to answer your very reasonable question at 1219. His failure to do so, I think, would be clear evidence that his only purpose here is trolling.
    Response: [muon] Indeed. This thread is about the 2nd law of thermo, not about boxes or greenhouses. Wood's experiment is off-topic.
  24. @1210 RW1 If you read G&T carefully you will find out that they do not state that IR photons or any other photons emitted by a gas do not travel in straight lines to whatever they are then stopped by. In fact they, as physicists who have published on quantum physics they have quit a nice explanation of how photons are involved in the transfer of heat both in conduction and radiation. Where they G&T disagree with you is in your definition of RGHE that, IIRC, you say requires heat to flow from the colder CO2 in the atmosphere to the ground. I believe G&T would use the term "Perpetuum Mobile of the 2nd kind" for what you are describing as your description of RGHE seems similar to one of the definitions they took exception to. Photons from the atmospheric gases (let's include all species here) can go in any direction but heat always flows from hot to cold. It is the basis for radiative heat transfer as described in G&T.
  25. TOP @1224, heat may always only travel from hot to cold, but only if you use a very specific, technical definition of heat to mean "net thermal energy". Energy, including thermal energy can travel in any direction including from cold to hot. G&T employ the former technical definition in order to refute the second possibility (as indeed you are also doing). It amounts to empty word play and has nothing to do with real science.
  26. @1225 Tom I guess if definitions aren't important to science then G&T is pretty well meaningless. IIRC they are trying to avoid word play by defining what they mean very precisely. How can one talk about RGHE if it is not well defined? G&T studied fourteen IIRC definitions of the RGHE and found at least one of them to describe a "Perpetuum Mobile of the 2nd kind" which I take to mean they found that definition of RGHE to be a violation of the 2nd law in that it described a perpetual motion machine. And yes, I'm tired of hashing over Wood too. So much more to discuss.
  27. 1223, Tom, Thanks. I hadn't reread the opening in a while, but you are right... the original point of the experiment was as stated, and the real problem is that the conclusion (amazingly) has little to do with the intended design. Wood sort of derailed there. But agreed, Wood is way off topic. This is best resumed by TOP, if he so chooses, after the Wood post is up on on that thread. That would be the right place for it. [Somehow, I now find myself dreading that day, however.] Am I right in thinking that TOP's use of the term RGHE refers to "radiative greenhouse effect?" (A term presumably created to distinguish it from "convective greenhouse effect?")
  28. TOP @1226, if you wish to discuss G&T's purported discovery that a particular definition of the Radiative Green House Effect (?) is a perpetual motion machine of the 2nd kind, summarize their argument including quotes of the most important sections, including, most importantly, the definition they are challenging and the cited source of that definition. Failure to find a cited source of the definition probably establishes the definition to be a straw man. You should probably confine your argument to this point as it is only this point that is actually on topic on this thread (which is not a generalized refutation of G&T).
  29. TOP, I note that you haven't yet come up with some clear idea of what physical quantity your IR thermometer measures. The basis of G&T's obfuscation piece is to confuse people like TOP to think that heat, in the thermodynamic sense, is the same as energy. Energy can flow from the atmosphere to the surface, heat can not. Their game is made easier by the fact that the word is used with less care than it deserves in popular explanations. Nowhere in radiative atmospheric physics is there a sugggestion that heat flows from the atmosphere to the surface. Anyone who believes that will be fooled by G&T's game. I don't know how this paper made it through peer-review, it is of no interest whatsoever. I reiterate that G&T do not have a point. However, there is no shortage of individuals who are not really qualified, yet draw from it enough arrogance to go on pontificating that atmospheric physicists have it all wrong. That is why this thread was necessary, not because there is any substance in G&T.
  30. Spherica, Tom, TOP - I introduced the term "radiative greenhouse effect" quite some time back in this thread - for the specific purpose of avoiding abuse of and confusion between convective (glass) greenhouses. I realize that's perhaps not a standard term, but I've found it useful in disambiguating the discussion. My apologies if it has been confusing. I would suggest continuing a practice of expanding acronyms the first time they are used. TOP - G&T's paper mostly consists of an extended and repetitive set of strawman arguments. They misrepresent the radiative greenhouse effect as the convective greenhouse effect, they misrepresent various energy transfers as the net transfer (heat), most clearly in their Fig. 32 (where they simply and distortingly do not show the full set of energy flows), etc. And once they have created these strawmen, they attack arguments that are not physical, and simply not made, by the scientific community. Add to that the near-Victorian language, the continual tone of 'scolding', and lots of irrelevant side trips such as the 8-10 pages of semantic games with the definitions of greenhouse effects, and G&T lack rigour, content, or any connection to reality. The entire paper is semantic games, rhetoric, and strawmen. Hence the multiple (and to date unmet) requests for you to identify something in the paper (other than semantic gaming) indicating some physical basis for objecting to the (radiative) greenhouse effect that G&T don't seem to actually discuss.
  31. @1224 Tom and 1219, 1221 Sphaerica First of all to Tom. While I am writing responses to posts other post are made which I don't see until I submit my post. If you take this to be avoiding answering 1219, so be it, but I think you will find I was writing 1220 at the time 1219 was also being written and submitted. I seem to be having to answer several posts simultaneously and this has to be done one at a time. And of course I can no longer respond to 1221 or 1223 either. Tom I appreciate that you restated much of what I stated in 1220. To clarify RGHE see @465,859 and others. KR uses this term frequently in this thread and others without complaints. Now to ask the question that Sphaerica requested: In G&T they quote this definition of RGHE from Stichel:
    “Now it is generally accepted textbook knowledge that the long-wave infrared radiation, emitted by the warmed up surface of the Earth, is partially absorbed and re-emitted by CO2 and other trace gases in the atmosphere. This effect leads to a warming of the lower atmosphere and, for reasons of the total radiation budget, to a cooling of the stratosphere at the same time.”
    to which G&T respond, " "This would be a Perpetuum Mobile of the Second Kind. A detailed discussion is given in Section 3.9. Furthermore, there is no total radiation budget, since there are no individual conservation laws for the different forms of energy participating in the game. (T&G p39)" Question 1 G&T make the assertion that Stichel's definition of RGHE is a violation of the 2nd Law. Is this definition a violation of the second law and if so why or why not? In particular I believe Stichel's choice of the term "warming" has something to do with G&T's response as in the colder atmosphere is raising the temperature of the warmer ground. Question 2 G&T make the assertion that there are no individual conservation laws for different forms of energy [which I take to mean that energy has to be taken as a whole to be conserved]. If you look at Tom's point #1 in 1181 he produces a picture of from Ternbeth et al, 2009 showing 333 W/m2 of something called backradiation flowing back to the earth's surface. Is this back radiation a "heat flow" that can raise the earth's temperature? If it is a "heat flow" is it occurring from a colder to a warmer body in general? Question 3 I will also add a question about Ternbeth's graphic since it appears so many places. It shows a convection (thermals) and a latent heat flow of heat in one direction, up. Why does it not also show the counter convection heat flow and latent heat flow down as occurs when rain falls or cold air sinks to the surface? When I took thermodynamics we had to clearly define the boundaries around which we considered heat and work moving in and out.
  32. @1230 KR You do realize that one or both author's (Gerlich & Tscheuscher) speak German as their first language? I wouldn't take this as indicative of some attitude on their part. I have read other author's who speak German as a first language and have found some of these turns of speech prevalent there also. German grammar is different that English grammar an can color the lanquage of a non-native speaker. I appreciate that they took the time to communicate in English and most of all to translate important quotes into English.
  33. 1231, TOP, Okay. Please note that G&T do not in any way make their case. They do absolutely nothing more than to say, in so many words, "2nd law, you lose." Their entire section 3.9 is nothing more than a repetition of explanations of accepted Thermodynamics. They then finally get to page 78 where they quote Rahmstorf as saying that the second law is not violated, to which they simply say what Rahmstorf would agree with, that it is energy, not heat, being exchanged, which could be an argument for exactly why the second law is not violated. In the end, they have made no point. They then attack a phrasing of the issue in Wikipedia. Wow. What earth shattering scientific prowess they show! They have published a peer-reviewed paper to correct Wikipedia! And yet G&T present no evidence or clear argument whatsoever. They do nothing more than stomp their feet and shout "2nd Law." There is nothing there to argue with. G&T is a total and complete waste of everyone's time. Honestly, the International Journal of Modern Physics must be a pretty crappy journal to have published it. I'd refer you to Comment on "Falsification of the Atmospheric CO2 Greenhouse Effects within the Frame of Physics" by Halpern et al.
  34. @1230 KR Figure 32 It just raises the question which I raised in 1231 Question 3, "Where is the boundary across which RGHE is expressing a heat balance?" G&T put it at the stratosphere. Ternbeth uses the term "atmosphere" in depicting some nebulous boundary. G&T go on to quote Rahmstoff in discussing the figure, but Rahmstoff uses the term atmosphere not stratosphere. Rahmstoff clarifies, "However, the second law is not violated by the greenhouse effect, of course, since, during the radiative exchange, in both directions the net energy flows from the warmth to the cold.” It seems like the RGHE is trying to mix microscopic phenomenon "radiative energy transfer by means of photons" with macroscopic effects, heat flow. Is the major transfer of heat from the atmosphere to the surface in either direction primarily through conduction or radiation?
  35. @1233 Sphaerica Which question were you answering? It would help me if you specified which question you are answering. I'm pretty thick you know. You asked me for specific questions. The least you could do is give specific answers. I have Halpern and I have response to Halpern. I also have versions 1-4 of G&T's paper. Still working through them.
    Response: [DB] Your link is corrupted.
  36. Sorry, how is this? response to Halpern

    [DB] Close enough that I was able to fix it.  :)

  37. 1231, TOP, I'll answer your question 3 for now because it's the easiest. The "heat" doesn't come back down with the rain. The water comes back down, but the direction of energy transfer is only one way. Water evaporates, gains energy. Water vapor rises. Water condenses, transferring the extra energy to the surrounding atmosphere. Condensed water falls as rain. When cold air sinks to the surface... it's, umm, cold! No heat carried down with it.
  38. 1235, TOP, I didn't answer any of your questions in post 1233, I simply pointed out that your response about the section of G&T claiming that GHE represents a perpetual motion machine has no foundation. They offer no support. They point to section 3.9 which gives the standard discussion of thermodynamics and perpetual motion machines, but they never demonstrate how this relates to the GHE. For your questions: 1) I can't begin to tell you, because as you point out, the G&T comment is mere assertion without further explanation or support. They do so throughout the paper, which is why it is a waste of words. 2) Again, an unexplained G&T assertion, although I would clarify that "heat" is not exactly a "form" of energy. Heat and temperature are both useful quantifications (perceptions) of energy. To clarify, consider that when you touch hot pavement what you are sensing as heat is the rapid vibration of the molecules in your (solid) skin, as a result of the heat transfer from the pavement to your skin. Those vibrations are caused by a combination of the transfer of kinetic energy from the vibrations in the molecules of the pavement as well as IR emissions resulting from the relaxation of some of those vibrations. On the other hand, when you sense heat in the wind from a hair dryer, because you are dealing with a gas and not a solid, the vibrations in the molecules of your own skin are caused primarily by the velocity of molecules in the gas (and, again, by IR radiation, as well as possibly vibrations and rotations if the molecules are complex enough — like H2O — to have vibrational and/or rotational modes). "Heat" and "temperature" are concepts that arise naturally from the observations of the macroscopic world around us, but looking further into inner space we find that these are mere mathematical, perceptual constructs which help us to describe large systems in aggregate, but do not exist in and of themselves as distinct "things." Thermodynamics itself, in fact, is a holdover from an age where only macroscopic analysis, concepts, descriptions and relationships were possible. Unfortunately, too many people seem unable to move beyond this or, more importantly to reconcile the combination. That G&T get caught up in the distinction between heat and energy without themselves being able to clearly articulate how the distinction does and does not apply the the process behind the greenhouse effect speaks to either their poor abilities as communicators or their poor understanding of the subject they are tackling (or both).
  39. 1235, TOP, You might want to look here for more about G&T. But... Based on your posts, my feeling is: 1) Your own foundation in science, while not "poor," is incomplete. The fact that you were confused by latent heat and convection as a heat transport mechanism in the atmosphere, as well as what you were measuring with a handheld IR thermometer, suggests to me that you need to start from scratch. Find a text on atmospheric physics and read it (learning it, rather than assuming that it is full of errors that you can riddle out as you go). 2) The bulk of your objection seems to fall back on G&T, i.e. an appeal to authority, when in fact that particular "authority" is alone, contradicted by all of the other authorities available, and who themselves are not able to clearly articulate their own case.
  40. @1239 Sphaerica Thanks for the link. I couldn't find the link to Halpern's January 25th material which G&T reference, but this will keep me occupied for a while. I assume most of what is here also found it's way into Halpern's refutation to G&T. Actually I don't know if was me or Trenbeth that was confused about latent heat and convection if you want to make a point of it. Look carefully at the diagram. Look just north of the Bering Straits. Trenbeth

    [DB] "I don't know if was me or Trenbeth that was confused about latent heat and convection"

    You would have us choose between believing

    1. you are possessed of a well-spring of D-K (equating yourself the equal of a subject area specialist in climate science and then arrogantly saying that one of you is confused)
    2. you are simply trolling here to cause confusion and mayhem.

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  41. TOP#1240: No fear, it's not Trenberth who's 'confused'. Run the numbers in that diagram again, they check.
  42. 1240, Trenberth is fine. Thermals carry 17 W/m2 up via warm air. That warm air is replaced by cooler, sinking air. Heat transfer is upwards only. Evapotranspiration puts 80 W/m2 into water vapor (i.e. water that evaporates from the surface). It rises and condenses, releasing its energy as latent heat to the surrounding atmosphere, and then the water, now devoid of that transported energy, falls as rain. Heat transfer is upwards only. This is all, I think, fairly clear, and coincides with what I have already explained. Do you still not follow it?
  43. TOP @1231, Stichel's definition is a perfectly acceptable definition of the greenhouse effect, if somewhat abbreviated. However: 1) If you look at G&T's more detailed discussion of Stichel's definition, you can see that they have interpreted him as saying that the greenhouse effect takes heat from the stratosphere and moves it to the surface, thus warming the surface. Stichel did not say this, and this is just one of many bizarre misinterpretations by G&T. As an aside I will note two examples of their misinterpretation. In the definition by the German Meteorological Society (3.3.8, pp 40-1) it says:
    "in the infrared range of the spec- trum the radiation emitted form the ground is absorbed to a large extent by the atmosphere ... and, depending on the temperature, re-radiated in all directions."
    (My emphasis) to which G&T respond:
    "The assumption that if gases emit heat radiation, then they will emit it only downwards, is rather obscure."
    (My emphasis) Well certainly it is obscure since it exists only in their interpretation, and is in direct contradiction to the claims of the German Meteorological Society. Later, in their response to Rahmstorf's definition (3.3.14 pp 43-4) G&T say:
    "Obviously, reflection is confused with emission."
    Perhaps, but the confusion is entirely on their part as Rahmstorf never mentions reflection. Indeed, G&T have again directly contradicted their source, for Rahmstorf he talks about:
    "... the portion of the long-wave radiation ... which is radiated by the molecules partly downward and partly upward."
    (My emphasis) Such blatant distortions of the views of those they criticize must make the work of a critique very easy, but also completely worthless. Returning to G&T's misinterpretation of Stichel, obviously a transfer of heat from the cold stratosphere (average temperature around -10 degrees C) to the warm surface would be a violation of the 2nd law of thermodynamics. It would also be completely insufficient as an source of the surfaces warming because of the relative heat capacity of the ocean and the stratosphere. It is also completely irrelevant to any sane discussion of the atmospheric green house effect as nobody proposes that as a mechanism of that effect. 2) The back radiation is a flow of thermal energy from a cold to a warm source. However, using a strict definition as, for example, is used by Philippe Chantreau's excellent comment @1229, and sometimes by G&T, it is not a flow of heat. Using that strict definition, "heat flow" is the net transfer of thermal energy between two points. That means (loosely*) that the 2nd Law of thermodynamics states only that the net transfer of thermal energy between two points must be from the a hotter to a colder source. Because the 2nd law only talks about the net transfer way of thermal energy, it in not way prohibits transfers of thermal energy from the atmosphere to the surface. Further, as you can see from the energy balance diagram, the net thermal transfer is from the surface to the atmosphere. I note in passing that G&T only sometimes use the strict definition of heat. Indeed they frequently use that definition to justify the assertion that heat can never flow from a colder to a warmer location. However, in criticizing Rahmstorf's discussion of the 2nd law (section 3.9.3, page 78), saying:
    "Rahmstorf's reference to the second law of thermodynamics is plainly wrong. The second law is a statement about heat, not about energy. Furthermore the author introduces an obscure notion of "net energy flow". The relevant quantity is the "net heat flow", which, of course, is the sum of the upward and the downward heat flow within a fixed system, here the atmospheric system. It is inadmissible to apply the second law for the upward and downward heat separately rede ning the thermodynamic system on the fly."
    If you are using the strict definition of heat, then the term "net heat flow" is nonsensical. There cannot be a heat flow, both up and down at the same time in order for there to be a 'net heat flow' under that definition, so G&T's claim here is nonsensical. In fact what they have done is slipped into the common definition of heat to refute Rahmstorf while retaining the distinct and contradictory strict definition for the rest of you discussion. When you allow yourself such blatant equivocation, you can prove anything you like (including, in a favourite example from my childhood, that a penny is a shilling.) Given the way that G&T play loose with word meanings, and radically misinterpret their sources, they can not be relied on as an authority, or source of instruction in any way. Their paper is so bad that it could well constitute evidence of academic misconduct, and not just incompetence. I cannot understand why you are using it as a source. I note that G&T's first criticism of Rahmstorf over discussing energy ignores the fact that the laws of thermodynamics have been generalized to apply to all energy transfers. That Rahmstorf uses the physics of the 20th century, while G&T wish to restrict themselves only to the physics of the early 19th century is no valid criticism of Rahmstorf. (* I said loosely because fridges are a counter example to this definition, and hence to the definition as used by G&T, but not a counter example to the law as strictly stated.) 3) In nearly all instances of heat transfer by precipitation, the heat transfer is from the ground to the atmosphere. That is because when precipitation returns to the ground (as water in either solid or liquid form) it is typically colder than when it left it (as water vapour).
  44. @1241 muon I know. I added them up. Other than a little rounding the math is fine. Not saying anything about the math. I meant to say me and Trenberth. @1242 Sphaerica Follow it just fine. @1243 Tom In #3 you sort of get my point in 1239. Both sinking cold air and rain, snow or ice all have heat content when they reach the earth. It's just that they are at a lower temperature so when the cycle begins again they are heated or receive heat of evaporation or fusion to be lifted up in the atmosphere. So by analogy why treat the "cold" back radiation any differently. Why not just say that the net upward radiative heat flow to the atmosphere is 23 W/m2? It makes it a lot easier to put in perspective the effect of RGHG (Radiative GreenHouse Gases).
  45. TOP#1244: "they are heated or receive heat of evaporation or fusion to be lifted up ... So by analogy why treat the "cold" back radiation any differently." You're kidding, right? Because there is no 'analogy.' Latent heat and convection are not radiative. Analogy: a similarity between like features of two things, on which a comparison may be based
  46. TOP @1244, it certainly is easier to say that: 1) Adding CO2 to the atmosphere reduces the net rate at which energy flows from the surface to the atmosphere, which 2) Cools the atmosphere, resulting in a reduction in the rate at which which energy flows from the surface and atmosphere to space, and 3) The additional CO2 also (and independently) reduces the rate at which energy flows from the surface and atmosphere to space; which 4) Results in the surface warming because the net rate at which energy leaves the surface has reduced while the rate at which energy enters the surface from the sun has remained the same; and that consequently 5) The increasing surface temperature (from 3) increases the net rate at which energy enters the atmosphere, thereby warming the atmosphere, and 6) therefore increases the energy leaving both the surface and atmosphere to space until the original balance of energy leaving for space is restored, with 7) both the surface and atmosphere being warmer in the final equilibrium condition than in the former equilibrium condition. There you have the entire greenhouse effect in a nutshell with no mention of back radiation, and no heat flowing from colder to warmer regions. It should be noted that the reduction in heat flow from surface to atmosphere is primarily through a reduction in convection the balance of which is restored in days, and further that the cooling that results in the atmosphere is concurrent with warming from preceding additions of CO2 in the atmosphere, so that given noisy data the signal of that initial cooling is undetectable. However, as soon as somebody asks, "How do you know? I must introduce the physics of radiation, and hence upward long wave radiation, and downward long wave radiation and all the other complexities you want us to avoid. If you want an account for children, then we can ignore back radiation. If not, we cannot.
  47. @1243 Tom 1) I suppose G&T could have misinterpreted Stichel. 2) Why I am using G&T as a source? It is the SoD! Nowhere in a refrigerator or air conditioner do you find heat flowing from hot to cold. The cooling coils inside are always colder than the inside box and the radiator on the outside is always hotter than the outside air. The fact that work is being added by the compressor to change the working fluids volume is not a heat flow.
  48. @1246 Tom Why not simplify even more? Using Trenberth as a reference point and taking the surface of the earth as the boundary within which we are accounting for heat: 396-333 = 63 W/m2 radiative heat across boundary. Of that 63 W/m2, 40 W/m2 goes directly to space and 23 W/m2 increases the heat content of the atmosphere from ground radiation. No confusion about heat flowing from cold to hot, no confusion at all by doing this simplification. And no chance for the 2nd law naysayers to squawk. It then makes it easier to put into perspective the effect of RGHG.
  49. TOP @1247: 1) Not only could, but clearly did. Their interpretation, as illustrated by figure 32 (page 78) is plainly absurd. 2) You have provided no explanation as to why you are relying on G&T as a source despite their obvious misinterpretations and equivocations. The only abbreviation of SoD that is relevant is "Science of Doom" an online science blog, and G&T are certainly not the Science of Doom. Nor is the fact that SoD discusses and eviscerates G&T justification for using it as a source. Quite the contrary. Finally, you have merely asserted that fridges do not violate the 2nd law, which they do not. Never-the-less, if I place water at 2 degrees C into my working freezer, it will fall in temperature to -2 degrees C, freezing in the process. In the meantime the excess heat released by my ice cubes will be lost from the heat exchange at the back of the fridge to the 30 degree C ambient atmosphere.
  50. TOP @1248, if you simplify to that level you cannot explain why the greenhouse effect works. Consequently you also cannot make predictions of how it will react when perturbed. Scientists do not operate with story book level explanations, and no amount of creative misinterpretation by the G&T's of the world is sufficient reason to retreat back into mysticism as you are suggesting.

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