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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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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.

Convection

Convection

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

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.

Advection

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

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.

Radiation

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 326 to 350 out of 1119:

  1. damorbel, I offered three explanations in my comment. The first one (1, 2, 3, 4) was addressed to you, in response to your comment that "The idea that planetary temperature is affected by its albedo is quite mistaken" and all the subsequent comments in which you've spread confusion about the relationship among albedo, temperature, and radiation balance. The second explanation I provided addresses the subject of this thread -- the (erroneous) claim that the greenhouse effect violates the second law of thermodynamics (a claim that you make, e.g., here). The third part of my comment above goes into more detail about why the greenhouse effect doesn't violate the second law of thermodynamics. That part of the comment is not addressed directly to you because even after seven pages of mostly incoherent commentary it's hard for me to be sure what exactly your claim is. The most common (and indeed, the only) skeptical argument I've seen re: the second law is the one discussed in this thread -- the claim that radiation from a colder atmosphere cannot flow to / reach / be absorbed by a warmer surface. See, for example, this comment at Science of Doom, which includes the following: “Does this radiation from the colder surroundings “reach” the solid body in the middle of the diagram?” Answer: No, the colder body radiation cannot reach and be absorbed by the warmer solid body causing the warmer solid body to heat-up. and Trenberth clearly shows the colder Atmosphere Back Radiation of 324 w/m^2 being ABSORBED by the warmer Earth’s surface. Anytime a body absorbes heat energy it’s temperature has to increase, the warmer Earth’s surface was warmed by the colder atmosphere. A CLEAR Violation of the 2nd Law. and AGW theory and the Greenhouse Effect has been proven to violate the 2nd Law of Thermodynamics and the Law of Conservation of Energy. [...] If Back Radiation actually reached and heated the Earth as Trenberth shows, then Parabolic Mirror Solar Ovens would produce heating Day and Night! and so forth, ad nauseam. If you can see the flaws in that person's argument, then congratulations! We have some common ground to work from. However ... if you still think there's some problem with the second law of thermodynamics, you need to be much clearer and more coherent in explaining where you think that problem lies. Your comments in this thread have tended to wander diffusely from one incoherent remark to another (e.g., the entire digression about albedo). If you're unhappy that I or others are failing to correctly restate the subtle nuances of your views, you could help out by being a bit more straightforward about what those views are.
  2. “The net heat flux is from the surface to the atmosphere; it's just a smaller flux than it would have been if the atmosphere weren't there (or didn't contain greenhouse gases)”. “This is all completely uncontroversial among physicists, earth and planetary scientists, and others who deal with radiation balances in their work. There is no fertile ground for AGW-skepticism here” In your post, Ned, there remains a failure to differentiate between heat and energy which is at the heart of the confusion in most of the AGW blogs. Heat (the ability to do work or raise temperature) is, by definition, the net transfer of energy between two bodies. It is wrong to consider source to sink, and sink to source, energy flows in isolation. That way madness (and perpetual motion) lies. That is why the revised Trenberth diagram is vastly superior to its misleading predecessor. Whether or not energy can do anything at all depends on its surroundings. That is why there are cooling towers on power station sites. The backward radiation on which SOD harps at inordinate length is the negative term in the Stefan-Bolzmann equation. Given that, with a few simplifying assumptions, it is very easy to calculate the greenhouse effect. Assume a spherical, heated, source in a vacuum, in direct contact with the absolute (more or less) zero of space. If the temperature of the source is Tsource, it will radiate energy, W, at a rate proportional to the fourth power of Tsource. Now surround the source with a spherical sink, close enough for us to neglect surface area corrections and (this is a thought experiment) with zero resistance to thermal energy, so that we can ignore temperature gradients. Assume that the sink is capable of absorbing all the energy radiated by the source. The sink will warm until, at equilibrium, it radiates to space the original source energy. In other words, to Tsink will rise to equal Tsource. Meanwhile, the source must warm to Tsource1 so that it can radiate the original input energy to the sink. That energy output, W, will now be proportional to the difference between the fourth power of the new source temperature, Tsource1 and the sink temperature, Tsink which will have risen to Tsource. In other words, Tsource1 to the fourth – Tsink to the fourth = Tsink to the fourth, because the sink is radiating the original energy, W, to space. But Tsink = T Source, the original source temperature, so : The new source temperature (to the fourth) = 2 * the original source temperature (to the fourth). So, finally, Tsource 1/Tsource = fourth root of 2 = 1.19 Since the moon is at 255K, we arrive at a plausible explanation of the greenhouse effect (0.19*255= 48.5K). The atmosphere does not warm the earth directly in a second law violating way; instead it acts as a radiative insulating blanket. Do we believe this explanation, Ned? Woods tried to test it by building two greenhouses – one radiative (ie OLR absorbent) and one non-radiative. Their internal temperatures were the same. And if we do believe it, ignoring Woods, what will happen if we increase the absorption of the atmosphere? Its temperature cannot increase because it must continue to radiate W to space. The source to sink temperature difference must also remain the same. So nothing will happen. Would you agree, Ned, that there is ample scope here for rational scepticism about the impact of increased CO2 in the atmosphere?
  3. Fred Staples wrote "if we increase the absorption of the atmosphere? Its temperature cannot increase because it must continue to radiate W to space. The source to sink temperature difference must also remain the same. So nothing will happen." Fred, you are using only the rules for equilibrium, but by increasing the absorption of the sink you've pushed it out of equilibrium. While the sink moves toward a new equilibrium, additional rules apply. Increased absorption by definition means that the sink retains some of the energy W that hits it. There is no rule insisting that the retained energy instantly be radiated. Instead, the rule about how much energy is radiated depends on the temperature of the sink. The temperature of the sink does not rise enough to cause all of the newly retained energy to be radiated.
  4. Fred Staples "Woods tried to test it by building two greenhouses – one radiative (ie OLR absorbent) and one non-radiative. Their internal temperatures were the same." Which proves very nicely that greenhouses work by limiting convection rather than by absorbing radiation. It tells us nothing about the atmospheric greenhouse effect other than that it's poorly named. "And if we do believe it, ignoring Woods, what will happen if we increase the absorption of the atmosphere? Its temperature cannot increase because it must continue to radiate W to space. The source to sink temperature difference must also remain the same. So nothing will happen." You're very nearly correct. The effective radiating temperature does indeed stay the same, but it moves upwards in the atmosphere. The result is that the surface temperature must rise This is the best simple explanation I've ever seen of it and may clarify for you (thanks to Science of Doom): Soden & Held, 2000
  5. Fred Staples - "Would you agree, Ned, that there is ample scope here for rational scepticism about the impact of increased CO2 in the atmosphere?" I would say that there is not. Greenhouse gases reduce the efficiency of emission (emissivity), as is clearly seen by satellite spectra of the Earth. Given the P = e * s * A * T^4 relationship of Power to emissivity, Stephen-Boltzmann constant, Area, and Temperature, if the emissivity goes down temperature must rise to radiate the same power.
  6. Fred> Assume that the sink is capable of absorbing all the energy radiated by the source. This is an incorrect assumption for your simple model, and it invalidates your conclusions. Instead of absorbing all the energy, picture your sink absorbing a fraction of the energy emitted by the source, with that fraction increasing as the absorptivity of the sink increases. You will find that your simple model does indeed predict warming with increasing absorptivity of your sink.
  7. VeryTallGuy, thanks! The figure in your comment here is the exact one I had in mind when composing this comment in the other thread. I couldn't remember where I'd seen that figure (from Soden & Held, 2000), spent a lot of time looking for it, and finally ran across the similar (but not quite as good) version at Chris Colose's website.
  8. The second law also desribes:increasing entropy and heat loss. Heat and temperature are 2 different things. Also it is the.zeroeth law that desribes two bodies next to each other,at two different temps,and the resulting heat flow from a warmer to cooler body as well, in terms of equilibration.
  9. Chemist1 @333 Also it is the.zeroeth law that desribes two bodies next to each other,at two different temps,and the resulting heat flow from a warmer to cooler body as well, in terms of equilibration. No, the zeroth law only establishes temperature as the property that is invariant when two systems are in thermal equilibrium, it says nothing about the direction of heat flow when they are not. This is covered by the 2nd law.
  10. important note: net heat flow Heat doesn't from warmer objects doesn't avoid cooler objects.
  11. I am sorry to have delayed a reply to the comments on my post. I quite literally lost the thread. The explanation you offer, Very Tall Guy, is the only plausible explanation of the AGW effect. It is the preferred explanation of the founding fathers over at RC, and you can find it in the Rabbet rebuttal of the G and T paper, (immediately following their absurd multi-layer, back-radiation explanation). It begins with the lapse rate, a function of gravity and specific heat, which has nothing to do with radiative effects. Without this lapse rate there would be no AGW. Increasing CO2 in the cold, dry, upper atmosphere, impedes outgoing radiation, and moves the effective radiation point to higher (and therefore) colder temperatures. Radiation is reduced, incoming radiation remains the same, and the whole atmosphere and surface warms up to compensate. As your drawing demonstrates, the lapse rate moves to the right. In the trade this is the “higher is colder” explanation. It is plausible, but is it true? There was no sign of unusual global warming until the mid-seventies, when satellites began to measure temperatures across all levels and latitudes of the atmosphere. The UAH charts at Global Warming at a Glance show the temperature movements in the lower and upper troposphere, every month. At the very least these temperatures movements should be the same. In fact, the upper atmosphere temperature has hardly changed, while the lower temperature increase is 1.4 degrees C per century. Several years ago RC claimed that this contrary effect was the result of cooling in the stratosphere, which distorted the readings. (If the facts don’t agree with the theories, so much the worse for the facts). Sadly, from 1995 to date (15 years), lower stratosphere temperatures have been constant. Before that, minor falls appear as step changes associated with violent volcanic eruptions. (HadAT radio-sonde results). So there we are, Ned et al. The only plausible AGW theory is doubtful, at best. The others, (back-radiation, heat trapping, blanket-style insulation etc) are either absurd or directly contradicted by experiments (Woods and Angstrom’s) or the second law. Incidentally, the point of the second law is that energy is not capable of doing anything (work or heat) without an increase in entropy. One final point. It is always entertaining to see my fellow physicists at RC patiently explaining that everything with a temperature above absolute zero will radiate energy. They then go on to exclude Nitrogen and Oxygen in the atmosphere, leaving it to the greenhouse gasses (in the thin upper atmosphere) to radiate most of earth’s surface energy to space.
  12. Fred Staples - "Higher is colder" is certainly part of the greenhouse effect. So is band broadening as greenhouse gases increase. Both effects (dropping the emissive power of GHG bands in the upper atmosphere and widening those bands) reduce overall thermal emissivity of the Earth to space. Reducing emissivity, as per the Stefan–Boltzmann law, reduces the power emitted to space at any particular temperature. This causes an imbalance, energy accumulates, temperatures rise, emitted power returns to match incoming power - and we're a bit warmer. Now - if you think the radiative greenhouse effect is contradicted by the second law of thermodynamics (as per the various canards of the G&T paper), I suggest you go discuss that on Science of Doom. SoD has written far more (and far better) than I on that subject.
  13. KR, I find statements like this "SoD has written far more (and far better) than I on that subject" are not verifiable without a link. Would you care to provide one so we can discover the point you are making? In 329 VeryTallGuy wrote "This is the best simple explanation I've ever seen of it and may clarify for you (thanks to Science of Doom): You are referring no doubt to the diagram in your post I do hope there are better explanations. Your diagram does not show how CO2 or any other GHG has a warming effect; all it shows is the standard averge lapse rate which is known to arise from the increase in pressure on descending through the atmosphere. What it also shows is that, when the Earth gets warmer it... does... indeed... get warmer! What your diagram shows applies equally to the heating effect of the Sun at different latitudes; there are quite different tempertures at different latitudes because of the lower angle of the Sun in the sky; it's called the cosine effect; it is one of the reasons for different climates in the first place! To have a diagram with the tropopause at the same height for different surface temperatures just illustrates how far from observational measurements it is possible to get; changes in the surface temperature are always reflected in the height of the tropopause. The height of the tropopause is governed by a number of factors of which the surface temperature is one. An equally important matter is the Stratosphere where the temperature increases with height, very nearly to the surface temperature, almost reversing all the temperature drop due to the lapse rate.
  14. damorbel - I would suggest looking at SoD's excellent Imaginary Second Law of Thermodynamics. Use the search function on his website - as I recall he has multiple pages on the subject. Gerlich et al 2009 is a horrible paper - there are plenty of discussions across the web discussing them in detail, which are quite easy to find. I personally regret the time I spent reading it, as I will never recover those wasted hours - the more advanced version of this page covers it pretty well, but SoD digs in to much greater depth. Arthur Smith is worth reading on it as well, as is the excellent peer-reviewed Halpern et al 2010 reply. The other major point of my post was in regards to blocked band widening and deepening due to increased GHG's and increasing altitude of effective emission, seen in the graphs here. Reduced emissivity to space means reduced power to space - an energy imbalance; the temperature will change until said imbalance is zeroed out again.
  15. Re 339 KR this is what your link to SoD's explanation of the 2nd Law actually says:- "In the case of the real “greenhouse” effect and the real 2nd law of thermodynamics, net energy is flowing from the earth to the atmosphere. But this doesn’t mean no energy can flow from the colder atmosphere to the warmer ground." "It simply means more energy flows from the warmer surface to the colder atmosphere than in the reverse direction." I repeat the relevant GHE blind spot; "But this doesn’t mean no energy can flow from the colder atmosphere to the warmer ground". How is it possible to say this and claim 'net flow' in the other direction? Net flow causes temperature change. It is a temperature increase in the cold upper atmosphere that takes place due to net (warm) radiation from the surface, not the surface being warmed by a (net) heat loss from the surface to the upper atmosphere as 'explained' by GHE 'theory'. Without the 'net flow' from the surface the GHGs will lose heat through radiation and cool down catastrophically, GHGs radiate IR as well as absorb it, that is what Tyndall discovered.
  16. damorbel - "Net" == summed, total, the amount actually moving after all elements are considered, etc. I suggest you read Roy Spencers excellent discussion, Yes, Virginia, Cooler Objects Can Make Warmer Objects Even Warmer Still. If you've already read it and disagree, read it again. Repeat until understood.
  17. damorbel - Rereading this thread, I have decided that it's not worth my while to rehash issues that have been discussed ad infinitum with you. You've been pointed at the appropriate information; I would suggest reading the thread over and working on understanding it. You've been given the data, you've been given multiple explanations - but your last post indicates you are repeating the same errors you've displayed from the very beginning. >300 comments later, and you're still holding to those physically incorrect views. Rehashing this topic with you yet again is a repetitive rhetorical exercise, unless you show some propensity towards learning. I'm not going to waste my time. Sorry about the rather harsh attitude; I'm just getting tired of people who simply refuse to learn.
  18. KR you write:- ""Net" == summed, total, the amount actually moving after all elements are considered, etc." Follow your own logic, KR. The Earth's surface is a 'net' loser of energy; the upper atmosphere a net gainer. My conclusion is that 1/the surface is a net loser because it is warmer than the upper atmosphere so it (tends) to cool down, being a net loser of energy to the upper atmosphere. And 2/ the upper atmosphere is a 'net' gainer, therefore it tends to warm up with the (net +ve) heat gain from the surface since the upper atmosphere is cooler than the surface. No need for SoD's explanation or a visit to the good Dr. Spencer to understand this, is there?
  19. damorbel I've thought about the difficulty of getting this particular point through to you, and have a small Excel exercise for you. First row (1): "Sun" "Earth" "Atmosphere" "Space" Second row (2): "240" "=A2+0.5*C2" "0" "=B2-0.5*C2" Third row (3): "=A2" "=A2+0.5*C2" "=0.2*B2" "=B2-0.5*C2" Copy the third row and paste it in the 4th-20th rows. The "0" in the second line is to avoid a circular reference, but the actual guts take place in the third row. This represents solar input energy (240), surface radiated energy, energy intercepted/spherically radiated by the atmosphere, and energy radiating out to space. Constants (such as the 0.2 of IR intercepted by the atmosphere) are illustrative, but not tied directly to real values. The 0.5 radiated up and down from the atmosphere goes directly to space or the surface, so this is essentially a single-layer radiative atmospheric model without convection. What you will see is that the atmosphere, due to redirecting half of the energy back to the surface, warms it so that it radiates ~267 rather than 240. Meanwhile, the output to space is still 240, regardless. A cool object (atmosphere) has warmed a warmer object (the surface). Try constants other than 0.2 for IR absorption, and see how it goes; a 0.3 absorption brings the surface radiation to 282. Energy comes in from the sun, goes out to space - and reflecting insulation keeps the surface warmer than it would be otherwise, while maintaining the conservation of energy. Think about it.
  20. I don't suppose RW1 or Co2isNotEvil can help in explaining things to damorbel? Would be nice to see the skeptics helping each other out rather than leaving all the hard work to KR :)
  21. damorbel Here's another Excel exercise. "Row 1: "Emissivity" "0.6" Right click the 0.6 and "Name a range" to "Emissivity" Row 3: "Sun" "Earth" "Emitted" "Difference" Row 4: "240" "=A4" "=B4*Emissivity" "=A4-C4" Row 5: "=A4" "=B4+D4" "=B4*Emissivity" "=A5-C5" Copy Row 5 and paste it into the next 20-30 rows. As the Earth emissivity goes down relative to a theoretic black-body, due to the widening/deepening GHG bands in the spectra of the total planetary emission, surface radiation must go up due to the difference (energy conservation) between incoming and outgoing radiation. I find an emissivity of 0.606 and input of 240 gives a surface radiation of 396, emission to space of (again) 240 on convergence. Interestingly enough, this is just about what the planetary emissivity has been calculated to be...
  22. Re 344 KR You very kindly provided an excel sheet for doing calculations showing energy tranferred by radiation without any indication of the relative temperatures between the heat source and the heat sink. Now it is a fundamental of physics that, without knowing these temperatures, you cannot make any energy transfer calculations or predict any temperature changes. You claim that I do not understand your arguments, do you understand my need to know what the various temperatures are involved in you 'warming' model? PS Your EXCEL explanation will not load in my MS EXCEL, Would you be so kind as to provide a clearer version; perhaps just the cell identities and the cell entries? Thanking you in advance.
  23. damorbel - When I worked up the two spreadsheets, I transcribed the content as individual cells with values surrounded by quotes. I've had little (read that, 'no') success in copy/pasting entire spreadsheets as text - hence the approximate formatting. Sorry about the difficulties; if it doesn't work blame my typing! For the first spreadsheet the initial setup is a set of 4 columns, 3 rows, with the items in quotes in each cell in order (don't type in the quotes!). Then copy the last line (4 columns) and paste it into the next 20-30 to converge. Here radiation to space is what's left over when the atmosphere returns some to the surface, and it converges when outgoing=incoming. For the second spreadsheet, the emissivity driven model, there's a single line with a "named range" of "Emissivity" (getting a bit tricker), initial value 0.6. Two rows down there's a section 4 columns across, 3 rows high, with items in quotes in individual cells (don't put in the quotes!). Copy those last 4 cells and paste into the next 20-30 lines for convergence. Try different planetary emissivities to see how the surface energy changes. Here "Emitted" is what's sent to space, and it again converges when outgoing=incoming. These are radiation only models, lacking (in the first example) any convection/evaporation, in order to make the point. In the first, I'm just looking at radiative energies - 240 W/m^2 from the sun, and in convergence 240 W/m^2 to space as IR. Since it's such a simple model temps are not going to be accurate, but it clearly shows that in the presence of an absorbing/spherically emitting atmosphere the surface will be radiating more than the input energy in order to put the total input energy out to space. The primary take-home from the first model is that surface radiated energy goes up in the presence of a GHG containing atmosphere, and that only happens if the temperature goes up. In the second model we can look at temperatures related to those energies; it's a simpler yet more accurate model looking at only the radiative elements. 240 W/m^2 is indeed the incoming solar power. 0.6 is close to the Earth emissivity (zero dimensional model). 396 W/m^2 is the energy radiated from the Earth's surface (surface temp of 14°C which should radiate ~390 given an emissivity of .91-.95, but surface variations and the T^4 relationship raise that to 396). This really simple model quite accurately captures surface emissions and hence surface temperature. I was actually quite surprised at how closely this agrees with the data. In either case - re-emission back to Earth, which shows as reduced emissivity of the planet to space, results in driving the surface to emit more energy to get the incoming 240W/m^2 back out to space, and hence conserving energy.
  24. damorbel - For temperatures in the second model, add a second "named range" of "Surface_E", value of ~0.97 (a better surface estimate, once I looked it up), and another column starting at E5 containing: =SQRT(SQRT(B5/(Surface_E*5.6704*10^-8)))-273.15-4 Copy this cell and paste down the column. This reverses the Stefan-Boltzmann equation to get degrees Centigrade, with a "4" fudge factor (sets the ~18C final result back to ~14C, accounting at least in part for the surface variations and T^4 increase in radiated power). Not perfect, but a reasonable back of the envelope correction. Given this model and that a doubling of CO2 should result in an imbalance of 3.7 W/m^2, the effective decrease in emissivity of 0.606 * 236.3/240 =.597, which fed into the model results in a temperature rise of ~1.1C, just about what everyone expects from a CO2 doubling with no feedbacks.
  25. Re 348 & 349 Thank you for your contributions, they enable me to appreciate how you calculate your results. But all that you write makes it increasingly clear that the idea that the upper atmosphere (UA) can raise the surface temperature simply doesn't work. Let us imagine for a moment that the surface and the upper atmosphere are at the same temperature. In this situation both surface and the UA are emitting photons with the same energy, that is a consequence of your formula SQRT(SQRT(B5/(Surface_E*5.6704*10^-8)))-273.15-4. The temperatures are the same because the energies of the photons from both sources are the same; there would be thermal equilibrium i.e. no energy transfer and no temperature change. In reality the UA is colder than the surface and your formula shows that the energy of its photons is lower than those of the surface, so the consequence is that energy is transferred to the UA (accordind to the 2nd Law of thermodynamics) where it is further radiated into deep space. Perhaps you find this difficult to accept but if the UA contained no GHGs at all it would not have a different temperature (apart from the stratosphere - which is warmed by O2 absorbing ultraviolet from the Sun) because heat is transferred in the atmosphere mainly by fluid flow e.g. convection. Below the stratosphere the temperature profile is largely determined by two factors, the temperature of the surface and the compression of the air due to gravity.

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