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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)


At a glance

Although this topic may have a highly technical feel to it, thermodynamics is a big part of all our everyday lives. So while you are reading, do remember that there are glossary entries available for all thinly underlined terms - just hover your mouse cursor over them for the entry to appear.

Thermodynamics is the branch of physics that describes how energy interacts within systems. That interaction determines, for example, how we stay cosy or freeze to death. You wear less clothing in very hot weather and layer-up or add extra blankets to your bed when it's cold because such things control how energy interacts with your own body and therefore your degree of comfort and, in extreme cases, safety.

The human body and its surroundings and energy transfer between them make up one such system with which we are all familiar. But let's go a lot bigger here and think about heat energy and its transfer between the Sun, Earth's land/ocean surfaces, the atmosphere and the cosmos.

Sunshine hits the top of our atmosphere and some of it makes it down to the surface, where it heats up the ground and the oceans alike. These in turn give off heat in the form of invisible but warming infra-red radiation. But you can see the effects of that radiation - think of the heat-shimmer you see over a tarmac road-surface on a hot sunny day.

A proportion of that radiation goes back up through the atmosphere and escapes to space. But another proportion of it is absorbed by greenhouse gas molecules, such as water vapour, carbon dioxide and methane.  Heating up themselves, those molecules then re-emit that heat energy in all directions including downwards. Due to the greenhouse effect, the total loss of that outgoing radiation is avoided and the cooling of Earth's surface is thereby inhibited. Without that extra blanket, Earth's average temperature would be more than thirty degrees Celsius cooler than is currently the case.

That's all in accordance with the laws of Thermodynamics. The First Law of Thermodynamics states that the total energy of an isolated system is constant - while energy can be transformed from one form to another it can be neither created nor destroyed. The Second Law does not state that the only flow of energy is from hot to cold - but instead that the net sum of the energy flows will be from hot to cold. That qualifier term, 'net', is the important one here. The Earth alone is not a "closed system", but is part of a constant, net energy flow from the Sun, to Earth and back out to space. Greenhouse gases simply inhibit part of that net flow, by returning some of the outgoing energy back towards Earth's surface.

The myth that the greenhouse effect is contrary to the second law of thermodynamics is mostly based on a very long 2009 paper by two German scientists (not climate scientists), Gerlich and Tscheuschner (G&T). In its title, the paper claimed to take down the theory that heat being trapped by our atmosphere keeps us warm. That's a huge claim to make – akin to stating there is no gravity.

The G&T paper has been the subject of many detailed rebuttals over the years since its publication. That's because one thing that makes the scientific community sit up and take notice is when something making big claims is published but which is so blatantly incorrect. To fully deal with every mistake contained in the paper, this rebuttal would have to be thousands of words long. A shorter riposte, posted in a discussion on the topic at the Quora website, was as follows: “...I might add that if G&T were correct they used dozens of rambling pages to prove that blankets can’t keep you warm at night."

If the Second Law of Thermodynamics is true - something we can safely assume – then, “blankets can’t keep you warm at night”, must be false. And - as you'll know from your own experiences - that is of course the case!

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

Among the junk-science themes promoted by climate science deniers is the claim that the explanation for global warming contradicts the second law of thermodynamics. Does it? Of course not (Halpern et al. 2010), but let's explore. Firstly, we need to know how thermal energy transfer works with particular regard to Earth's atmosphere. Then, we need to know what the second law of thermodynamics is, and how it applies to global warming.

Thermal energy is transferred through systems in five main ways: conduction, convection, advection, latent heat and, last but not least, radiation. We'll take them one by one.

Conduction is important in some solids – think of how a cold metal spoon placed in a pot of boiling water can become too hot to touch. In many fluids and gases, conduction is much less important. There are a few exceptions, such as mercury, a metal whose melting point is so low it exists as a liquid above -38 degrees Celsius, making it a handy temperature-marker in thermometers. But air's thermal conductivity is so low we can more or less count it out from this discussion.



Figure 1: Severe thunderstorm developing over the Welsh countryside one evening in August 2020. This excellent example of convection had strong enough updraughts to produce hail up to 2.5 cm in diameter. (Source: John Mason)

Hot air rises – that's why hot air balloons work, because warm air is less dense than its colder surroundings, making the artificially heated air in the balloon more buoyant and thereby creating a convective current. The same principle applies in nature: convection is the upward transfer of heat in a fluid or a gas. 

Convection is highly important in Earth's atmosphere and especially in its lower part, where most of our weather goes on. On a nice day, convection may be noticed as birds soar and spiral upwards on thermals, gaining height with the help of that rising warm air-current. On other days, mass-ascent of warm, moist air can result in any type of convective weather from showers to severe thunderstorms with their attendant hazards. In the most extreme examples like supercells, that convective ascent or updraught can reach speeds getting on for a hundred miles per hour. Such powerful convective currents can keep hailstones held high in the storm-cloud for long enough to grow to golfball size or larger.


Advection is the quasi-horizontal transport of a fluid or gas with its attendant properties. Here are a couple of examples. In the Northern Hemisphere, southerly winds bring mild to warm air from the tropics northwards. During the rapid transition from a cold spell to a warm southerly over Europe in early December 2022, the temperatures over parts of the UK leapt from around -10C to +14C in one weekend, due to warm air advection. Advection can also lead to certain specific phenomena such as sea-fogs – when warm air inland is transported over the surrounding cold seas, causing rapid condensation of water vapour near the air-sea interface.


Figure 2: Advection fog completely obscures Cardigan Bay, off the west coast of Wales, on an April afternoon in 2015, Air warmed over the land was advected seawards, where its moisture promptly condensed over the much colder sea surface.

Latent heat

Latent heat is the thermal energy released or absorbed during a substance's transition from solid to liquid, liquid to vapour or vice-versa. To fuse, or melt, a solid or to boil a liquid, it is necessary to add thermal energy to a system, whereas when a vapour condenses or a liquid freezes, energy is released. The amount of energy involved varies from one substance to another: to melt iron you need a furnace but with an ice cube you only need to leave it at room-temperature for a while. Such variations from one substance to another are expressed as specific latent heats of fusion or vapourisation, measured in amount of energy (KiloJoules) per kilogram. In the case of Earth's atmosphere, the only substance of major importance with regard to latent heat is water, because at the range of temperatures present, it's the only component that is both abundant and constantly transitioning between solid, liquid and vapour phases.


Radiation is the transfer of energy as electromagnetic rays, emitted by any heated surface. Electromagnetic radiation runs from long-wave - radio waves, microwaves, infra-red (IR), through the visible-light spectrum, down to short-wave – ultra-violet (UV), x-rays and gamma-rays. Although you cannot see IR radiation, you can feel it warming you when you sit by a fire. Indeed, the visible part of the spectrum used to be called “luminous heat” and the invisible IR radiation “non-luminous heat”, back in the 1800s when such things were slowly being figured-out.

Sunshine is an example of radiation. Unlike conduction and convection, radiation has the distinction of being able to travel from its source straight through the vacuum of space. Thus, Solar radiation travels through that vacuum for some 150 million kilometres, to reach our planet at a near-constant rate. Some Solar radiation, especially short-wave UV light, is absorbed by our atmosphere. Some is reflected straight back to space by cloud-tops. The rest makes it all the way down to the ground, where it is reflected from lighter surfaces or absorbed by darker ones. That's why black tarmac road surfaces can heat up until they melt on a bright summer's day.


Figure 3: Heat haze above a warmed road-surface, Lincoln Way in San Francisco, California. May 2007. Image: Wikimedia Commons.

Energy balance

What has all of the above got to do with global warming? Well, through its radiation-flux, the Sun heats the atmosphere, the surfaces of land and oceans. The surfaces heated by solar radiation in turn emit infrared radiation, some of which can escape directly into space, but some of which is absorbed by the greenhouse gases in the atmosphere, mostly carbon dioxide, water vapour, and methane. Greenhouse gases not only slow down the loss of energy from the surface, but also re-radiate that energy, some of which is directed back down towards the surface, increasing the surface temperature and increasing how much energy is radiated from the surface. Overall, this process leads to a state where the surface is warmer than it would be in the absence of an atmosphere with greenhouse gases. On average, the amount of energy radiated back into space matches the amount of energy being received from the Sun, but there's a slight imbalance that we'll come to.

If this system was severely out of balance either way, the planet would have either frozen or overheated millions of years ago. Instead the planet's climate is (or at least was) stable, broadly speaking. Its temperatures generally stay within bounds that allow life to thrive. It's all about energy balance. Figure 4 shows the numbers.

Energy Budget AR6 WGI Figure 7_2

Figure 4: Schematic representation of the global mean energy budget of the Earth (upper panel), and its equivalent without considerations of cloud effects (lower panel). Numbers indicate best estimates for the magnitudes of the globally averaged energy balance components in W m–2 together with their uncertainty ranges in parentheses (5–95% confidence range), representing climate conditions at the beginning of the 21st century. Figure adapted for IPCC AR6 WG1 Chapter 7, from Wild et al. (2015).

While the flow in and out of our atmosphere from or to space is essentially the same, the atmosphere is inhibiting the cooling of the Earth, storing that energy mostly near its surface. If it were simply a case of sunshine straight in, infra-red straight back out, which would occur if the atmosphere was transparent to infra-red (it isn't) – or indeed if there was no atmosphere, Earth would have a similar temperature-range to the essentially airless Moon. On the Lunar equator, daytime heating can raise the temperature to a searing 120OC, but unimpeded radiative cooling means that at night, it gets down to around -130OC. No atmosphere as such, no greenhouse effect.

Clearly, the concentrations of greenhouse gases determine their energy storage capacity and therefore the greenhouse effect's strength. This is particularly the case for those gases that are non-condensing at atmospheric temperatures. Of those non-condensing gases, carbon dioxide is the most important. Because it only exists as vapour, the main way it is removed is as a weak solution of carbonic acid in rainwater – indeed the old name for carbon dioxide was 'carbonic acid gas'. That means once it's up there, it has a long 'atmospheric residency', meaning it takes a long time to be removed. 

Earth’s temperature can be stable over long periods of time, but to make that possible, incoming energy and outgoing energy have to be exactly the same, in a state of balance known as ‘radiative equilibrium’. That equilibrium can be disturbed by changing the forcing caused by any components of the system. Thus, for example, as the concentration of carbon dioxide has fluctuated over geological time, mostly on gradual time-scales but in some cases abruptly, so has the planet's energy storage capacity. Such fluctuations have in turn determined Earth's climate state, Hothouse or Icehouse – the latter defined as having Polar ice-caps present, of whatever size. Currently, Earth’s energy budget imbalance averages out at just under +1 watt per square metre - that’s global warming. 

That's all in accordance with the laws of Thermodynamics. The First Law of Thermodynamics states that the total energy of an isolated system is constant - while energy can be transformed from one component to another it can be neither created nor destroyed. Self-evidently, the "isolated" part of the law must require that the sun and the cosmos be included. They are both components of the system: without the Sun as the prime energy generator, Earth would be frozen and lifeless; with the Sun but without Earth's emitted energy dispersing out into space, the planet would cook, Just thinking about Earth's surface and atmosphere in isolation is to ignore two of this system's most important components.

The Second Law of Thermodynamics does not state that the only flow of energy is from hot to cold - but instead that the net sum of the energy flows will be from hot to cold. To reiterate, the qualifier term, 'net', is the important one here. In the case of the Earth-Sun system, it is again necessary to consider all of the components and their interactions: the sunshine, the warmed surface giving off IR radiation into the cooler atmosphere, the greenhouse gases re-emitting that radiation in all directions and finally the radiation emitted from the top of our atmosphere, to disperse out into the cold depths of space. That energy is not destroyed – it just disperses in all directions into the cold vastness out there. Some of it even heads towards the Sun too - since infra-red radiation has no way of determining that it is heading towards a much hotter body than the Earth,

Earth’s energy budget makes sure that all portions of the system are accounted for and this is routinely done in climate models. No violations exist. Greenhouse gases return some of the energy back towards Earth's surface but the net flow is still out into space. John Tyndall, in a lecture to the Royal Institution in 1859, recognised this. He said:

Tyndall 1859

As long as carbon emissions continue to rise, so will that planetary energy imbalance. Therefore, the only way to take the situation back towards stability is to reduce those emissions.

Update June 2023:

For additional links to relevant blog posts, please look at the "Further Reading" box, below.

Last updated on 29 June 2023 by John Mason. View Archives

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Comments 1226 to 1250 out of 1254:

  1. @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.
  2. 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?")
  3. 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).
  4. 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.
  5. 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.
  6. @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.
  7. @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.
  8. 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.
  9. @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?
  10. @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.
  11. Sorry, how is this? response to Halpern

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

  12. 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.
  13. 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).
  14. 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.
  15. @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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  16. TOP#1240: No fear, it's not Trenberth who's 'confused'. Run the numbers in that diagram again, they check.
  17. 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?
  18. 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).
  19. @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).
  20. 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
  21. 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.
  22. @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.
  23. @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.
  24. 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.
  25. 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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