In 2009, Gerhard Gerlich and Ralph D. Tscheuschner (G&T) published a paper purporting to prove that there is no such thing as an atmospheric greenhouse effect. (“Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics”. )
This paper and its arguments are frequently referenced by those who deny that Anthropogenic Global Warming (AGW) is happening. Yet, the paper has been largely ignored by mainstream climate scientists. People who deny AGW are often outraged that the conclusions of this paper have not been widely acknowledged and embraced.
I believe this paper is rightly ignored. None of its key conclusions are justified or valid. Its quality is way below that of a normal scientific publication, and it’s surprising that it managed to get published.
To directly answer the question: No, Gerlich and Tscheuschner did not prove there is no atmospheric greenhouse effect. They proved they have no idea what is meant by the “atmospheric greenhouse effect.”
Yet, some people believe in the conclusions of this paper. So, it’s likely to be educational to look at things a bit more closely.
At a high level, I experience the paper as having multiple serious flaws:
- The paper seems to be organized around misinterpreting and misrepresenting what other people believe, and then refuting that.
Generally, the statements being refuted are things that were said in popular science communications, or in encyclopedias, or in hundred-year old early scientific works. There seems to be little engagement with (or knowledge of) what is said in the modern academic literature of climate science.
- The refutations generally come in the form of sloppy verbal reasoning and inappropriate examples, with little attention to detail or rigor.
- The most important conclusions are justified by misinterpreting others’ arguments, applying purely verbal reasoning, and misapplying basic thermodynamics to achieve a false refutation.
- The other primary strategy in the paper seems to be one of arguing that “it’s all too complicated to be knowable,” justifying dismissing others’ attempts to build a base of established knowledge. This argument is intellectually dishonest. Many relevant things can be known, and are known, in ways that G&T fail to acknowledge.
- The conclusions of the paper are easily proven to be not consistent with reality.
I’ll address the conflict with reality, and then the core thermodynamic error.
Table of Contents
- Major Flaws
- Comparison with Reality
- Greenhouse Effect
- G&T’s Rejection of the Diagram
- Core Flawed Thermodynamic Argument
- Additional Published Critiques
- APPENDIX: ADDITIONAL LEARNING REGARDING G&T
Comparison with Reality
First, let’s address point #5 from above.
One of the key contentions of G&T is that re-emission of infrared radiation by gases in the upper atmosphere “can in no way heat up the ground-level air.” (p. 92)
It has long been known that, if one doesn’t account for such effects, simple thermodynamic calculations imply that the Earth should be at least 33ºC colder than it is observed to be. G&T criticized such calculations as being invalid, on various grounds.
So, in 2008, Arthur P. Smith published a paper refuting G&T’s work (which had at that time been released as a pre-print) with calculations addressing every single complaint G&T had made about prior calculations of this sort. The result was:
- Earth is 33ºC warmer than can be explained if one assumes no warming effect by infrared absorption and re-emission.
- Venus is 505ºC warmer than can be explained in G&T’s version of reality.
Venus is the hottest planet in the solar system. This is the case despite Venus having a very high albedo (reflectivity), which means that Venus absorbs less sunlight than does the Earth. Venus is significantly hotter than even Mercury. This is despite Mercury being closer to the Sun and absorbing 12 times as much solar power (per unit area) as does Venus.
The most notable feature of Venus is that it has an extremely thick atmosphere which is primarily made up of carbon dioxide (CO₂).
The temperature of Venus is easily explained if the atmospheric greenhouse effect is taken into account. Yet, in the world of G&T’s version of physics, the temperature of Venus is inexplicable, a 505ºC error in the theory. G&T’s conclusions are highly inconsistent with reality.
Let’s look at the “greenhouse effect” that G&T are trying to refute. This can be illustrated using Figure 23 from G&T (p. 59), below.
This diagram shows flows of energy (per unit time) being interchanged between three realms: the Earth’s surface (ocean and land), the atmosphere, and the Sun/space.
There are four distinct types of energy flows depicted:
- Shortwave radiation – Electromagnetic radiation with a wavelength of less than 4 microns. This includes ultraviolet light, visible light, and near-infrared radiation. Over 99% of incoming Solar radiation is in this range.
- Longwave radiation – Electromagnetic radiation with a wavelength of more than 4 microns. This includes far-infrared radiation of the sort that is spontaneously emitted by materials on the Earth’s surface and in the atmosphere.
- Sensible heat flux – Heat transfer via convection and conduction.
- Latent heat flux – Heat transfer via the evaporation of water and movement and condensation of water vapor.
Each energy flow is normalized such that the energy per unit time from incoming Solar radiation is defined to be 100 units.
The diagram has the characteristic that the energy flows are balanced. Such balance is expected theoretically and confirmed by measurements. The total energy flows to and from the Earth’s surface are equal, so that the total thermal energy of the Earth’s surface is more or less stable. (In detailed climate models, this energy balancing is done on a localized basis, rather than for the whole Earth.) Similarly, the energy flows to and from the atmosphere are balanced, so that the total thermal energy in the atmosphere is more or less stable.
Such stability in total thermal energy must hold fairly accurately on average, because feedback mechanisms are present that naturally balance heat gain and heat loss. When more heat is gained, temperatures rise, leading to more heat being lost. When more heat is lost, temperatures fall, leading to less heat being lost. These mechanisms dynamically determine the temperatures in the system.
The “greenhouse effect” relates to the impact on the system of longwave radiant energy from the Earth’s surface being blocked from reaching space, and longwave radiant energy flowing from the atmosphere to the Earth’s surface.
In the diagram, there are 146 units of power (energy per unit time) flowing to the Earth’s surface, balanced by 146 units of power flowing away. The “back-radiation” (from the atmosphere to the Earth’s surface) is depicted as involving 100 units of power.
If the power of back-radiation from the atmosphere were, for some reason, to increase to 110 units, then:
- This would initially imbalance things, so that the Earth is receiving more power than it is losing.
- This would increase the net thermal energy, and the overall temperature, of the Earth’s surface.
- As the surface temperature increased overall, this would cause the Earth to radiate more longwave (thermal) radiation, increase evaporation (latent heat flux), and likely increase convection (sensible heat flux) as well.
- After the overall temperature of the surface of the Earth increases sufficiently, the energy flows away from the surface of the Earth would once again balance the energy flows received by the surface of the Earth.
- At this point, the system stabilizes, with the surface of the Earth at an overall higher temperature than it was at before the increase in back-radiation.
When longwave absorption and back-radiation from the atmosphere increase, the temperature of the surface of the Earth increases. This is what is called the “greenhouse effect.”
Human activities increase the levels of “greenhouse gases” like CO₂ and methane in the atmosphere. Greenhouse gases are the gases that are capable of absorbing and emitting longwave radiation. (Water vapor is also a greenhouse gas, but the level of water vapor in the atmosphere is not an independent variable; it is a function of the temperature of ocean surfaces.) Increased levels of these human-generated gases are predicted to increase back-radiation, resulting in the temperature of the Earth’s surface rising. That’s why there is concern about emission of these gases into the atmosphere.
G&T’s Rejection of the Diagram
G&T’s comment on the above diagram is (p. 59) “Diagrams of this kind contradict to physics.” [sic] This assessment is not justified in any explicit or clear way.
Mainly, G&T seem to obstinately refuse to understand what the diagram could possibly mean. They say (p. 59) “in the literature on global climatology it is not explained, what the arrows in ‘radiation balance’ diagrams mean physically.” G&T make a number of silly, overcomplicated, wrong guesses as to what arrows in the diagram might mean, dismissing each in turn, and then give up, concluding that the diagrams are “nonsense.”
Such diagrams, as G&T recognize, illustrate how climatologists conceptually understand the thermal dynamics underlying planetary temperature regulation. Given that G&T cannot understand the (rather simple) meaning of such diagrams (as explained above), it’s no wonder that G&T cannot understand the greenhouse effect.
Core Flawed Thermodynamic Argument
G&T assert (p. 92) back-radiation “can in no way heat up the ground-level air against the actual heat flow.”
By way of justification for this claim, G&T assert, repeatedly (p. 39, 76, 78, 92) that “This would be a Perpetuum Mobile of the Second Kind.”
For those unfamiliar with this jargon, a “Perpetuum Mobile of the Second Kind” is a perpetual motion machine that involves heat flowing spontaneously from a cool heat reservoir to a warm heat reservoir. Such a spontaneous heat flow from cool to warm is a violation of the Second Law of Thermodynamics, and is impossible.
To illustrate their concern, G&T offer their Figure 32, below.
The picture depicts heat flowing from the cool stratosphere to the warm ground.
In the caption for this diagram, they say (p. 78) “A machine which transfers heat from a low temperature reservoir (e.g. stratosphere) to a high temperature reservoir (e.g. atmosphere)[sic] … cannot exist… A modern climate model is supposed to be such a variant of a perpetuum mobile of the second kind.”
The problem is that G&T’s illustration is a false characterization of “a modern climate model.” No climate model involves heat transfer in the direction depicted.
To clarify this, it helps to draw another diagram which is equivalent to the diagram we previously used to illustrate the greenhouse effect.
This diagram represents the same energy flows as in the previous diagram (G&T Figure 23), but with less detail. The thick grey lines depict heat flows between each part of the system. (“Heat” by definition refers to a “net” energy transfer.) As one can readily see, in every instance, heat flows from hot to cold.
Heat flows are balanced. The heat flow to the surface of the Earth (46) is balanced by the heat flow away from the surface to the atmosphere and into space (37+9). The heat flows to the atmosphere from the Sun and the surface (23+37) are balanced by the heat flow away into space (60). It is necessary for the heat flows to be balanced in this way so that the total thermal energy present in each realm is stable.
In the case of energy transfers between the surface of the Earth and the atmosphere, the net heat flow from Earth to atmosphere (37) is made up of a flow from the Earth to the atmosphere (137) made up of thermal emissions from the Earth (106), convection (7), and evaporation (24), from which one needs to subtract back-radiation (100).
Despite the presence of back-radiation, which is an energy flow from the atmosphere to the surface of the Earth, the net heat transfer is from the surface of the Earth to the atmosphere.
Everything is consistent with the Second Law of Thermodynamics (“heat flows from hot to cold”), contrary to G&T’s characterization of climate models.
Let’s name the situation as depicted above situation Alpha. Let us consider what might happen in another situation, situation Beta, in which the back-radiation energy flow increased from 100 to 110. Perhaps it would look like something like what is depicted in the following diagram.
As in the previous situation, the heat flows must be balanced so that the total energy at the surface of the Earth, or in the atmosphere, is stable.
In order to achieve such a balance, an increase in the back-radiation must be compensated by changes in other energy flows. I’ve shown one hypothetical example of what the flows might look like after such compensating adjustments have occurred.
In this example, the thermal radiation leaving the surface of the Earth has increased (from 115=106+9 to 121=112+9), as has convection and evaporation. Matter at a temperature 𝑇T radiates with a power 𝝐𝛔𝑇4𝝐𝛔T4. (In this equation, 𝑇T is the temperature relative to absolute zero, 𝛔𝛔 is a universal constant, and the emissivity 𝝐𝝐 is a number between zero and one which is characteristic of the particular type of material.) So, for thermal radiation to have increased in situation Beta, there must have been an increase in the overall temperature of the surface of the Earth. This happened in order to balance energy flows.
Comparing situation Alpha and situation Beta, we see that:
- Increased back-radiation lead to an increase in the overall temperature of the surface of the Earth.
- In both situations, heat always flows from hot to cold. (Both situations satisfy the Second Law of Thermodynamics.)
So, we’ve just walked through an example of how the greenhouse effect can lead to increased temperatures. Yet, a violation of the Second Law of Thermodynamics (as G&T have asserted must be present) is nowhere in sight.
Where did G&T’s thinking (and the thinking of many who deny the greenhouse effect) go wrong?
The problem seems to be one of misinterpreting ambiguous language.
Consider the phrase “back-radiation (from the atmosphere to the surface) leads to an increase in the surface temperature.”
- G&T (and some other people confused by the greenhouse effect) mis-translate this to mean “heat flows from the atmosphere to the Earth’s surface.” They rightly say “That’s impossible!”
- Yet, what is actually meant is, “If you compare a situation with less back-radiation and a situation with more back-radiation, the latter situation will have a higher surface temperature.” This involves no flow of heat in any forbidden direction.
One meaning of the phrase “A warms B” is “heat flows from A to B.” However, a very different meaning of the phase “A warms B” is “When you add A to a situation, this results in B being warmer.” These are entirely different meanings!
Climate scientists sometimes informally use “warms” in the latter sense, and G&T (and others) have misinterpreted them as meaning the phrase in the former sense.
The core of G&T’s alleged “falsification” of the atmospheric greenhouse effect relies entirely on verbal reasoning, without any rigorous mathematics. (Although there are many equations in the paper, they relate to secondary issues or review things most scientific readers already know.) Verbal reasoning is ambiguous and unreliable.
G&T failed to understand what they were criticizing, at a very core level.
As a result, their verbal reasoning and central conclusions were entirely wrong.
Additional Published Critiques
- A. P. Smith (2008) showed that G&T’s conclusions are inconsistent with reality.
- Halpern, Colose, Ho-Stuart, Shore, Smith and Zimmernann (2010) refuted key thermodynamic errors in G&T, and offered a comprehensive critique and rebuttal. (Those persuadable by G&T may find the academic style of this beyond them. This paper is behind a paywall.)
- A series of critical blog posts by a climate scientist provide additional perspective on G&T’s paper.
- Evidence of the existence of “back-radiation” from greenhouse gases is illustrated in this blog post. It is unclear if G&T’s assertion that a radiation-balance diagram “contradicts physics” means they deny the existence of back-radiation, or something else.
G&T were unable to understand what people mean when they talk about the atmospheric greenhouse effect. G&T misinterpreted what others said, and based on those misinterpretations, they relied on verbal logic that led to false conclusions.
Observations, especially as reflected in the temperature of Venus, clearly demonstrate that the conclusions of G&T are thoroughly inconsistent with reality.
That’s really all you need to know.
* * *
Yet… the myriad mistakes in G&T correspond to memes that seem to circulate within the community of people who deny the reality of the greenhouse effect.
So, although this completes my main answer of the question, it may be helpful to some people if I comment on some of the lesser misunderstandings in G&T.
APPENDIX: ADDITIONAL LEARNING REGARDING G&T
Some Teaching First: Slowing Heat Loss from a Heat Source Raises Temperature
There is an abstract principle of thermal physics that G&T (and others) seemingly fail to appreciate:
In steady-state, the temperature of an object that is being continually heated will be lower when heat leaves easily, and higher when some mechanism impedes the loss of heat.
Let’s look, abstractly, at what we are talking about.
We have an object for which heat is flowing into it on an ongoing basis, e.g., with power (energy/time) P. Heat is lost through some generalized “thermal system” to a heat sink at a fixed temperature, T0. For the overall system to be in equilibrium, the heat flowing into the object must equal the heat flowing out of the object, i.e., Pin = Pout.
The question of interest is, what will be the temperature of the object of interest, T1?
Some people seem to have a false belief that the heat source alone determines this. But, how would that work? If the heat source is sunlight, the object of interest will not automatically be at the same temperature as the Sun. If the object is an electrical resistor, and 10 watts of electrical power are being generated inside, what would be the temperature? The answer does not depend on the heat source alone. Temperature depends on the thermal system regulating the loss of heat.
For any generic passive thermal system, there will be some relationship between the temperature difference across that system, ∆T = (T1−T0), and the rate of heat flow through the system, P. In general, can describe this relationship by a function, ∆T = f(P).
If f(P) is a simple linear function, f(P) would determine the temperature as shown below.
This diagram shows two different heat transfer functions, characterized by different values of “thermal resistance”.
For a fixed power through the system, a system with a small thermal resistance, R1, yields a small temperature difference, ∆T1, while a system with a larger thermal resistance, R2, yields a larger temperature difference, ∆T2.
Thermal systems involving conduction and convection are often treated as if they obey this sort of linear heat transfer function. Yet, the general conclusion, that the nature of the heat transfer function sets the temperature, does not depend on the function being linear.
Nor, does the applicability of the principle depend on the details of the thermal system. In general, the “thermal system” could involve any combination of radiation, convection, conduction, and latent heat flow, through some combination of objects, liquids, gases, and vacuum. These details do not alter the general principle.
Let’s look at some concrete examples:
- Consider a house during cold weather. If a house has more insulation (heat has more difficulty leaving), then it can maintain a given target temperature using less heating power; or for a fixed heating power, it will achieve a higher temperature the more insulation is present. In particular, the interior of the house will be warmer than the outside by an amount ∆T=φ×Rval where φ is the power per unit area and Rval is the R-value of the insulation.
- Consider an electrical resistor with a fixed current flowing through it, so that it dissipates a fixed amount of power. The resistor will be warmer than the ambient temperature by an amount ∆T=P×R where P is the power and R is the thermal resistance. The higher the thermal resistance, the higher the temperature. The thermal resistance depends on the characteristics of the structure to which the resistor is attached, and also on the quality of air flow or convection across that structure.
- Consider a greenhouse. Sunlight heats the interior of the greenhouse on an ongoing basis. There is some function that relates how much warmer the interior of the greenhouse is that the ambient temperature to the solar heat received: ∆T=f(P). For a given power P, anything that makes it harder for heat to leave the greenhouse will lead to a larger ∆T, i.e., it will make the greenhouse warmer.
- The atmospheric greenhouse effect is also an example of this. Sunlight heats the surface of the Earth on an ongoing basis. There is in principle some function that relates how much warmer the surface of the Earth is than the temperature of space to the solar power that must be dissipated to sustain an equilibrium: ∆T=f(P). The more power that needs to be dissipated into space, the larger will be the temperature difference. Anything that affects how easy it is for heat to leave the surface of the Earth and make it all the way to space will affect f(P) and, consequently, ∆T. If there were no greenhouse gases, heat leaving the Earth’s surface would efficiently reach space, and the Earth would be cooler. The presence of greenhouse gases makes the flow of heat from the surface of the Earth out to space less efficient. This leads to a higher surface temperature.
Regardless of the details of the thermal system, if there is (even on average) a fixed rate of heat flowing into the object of interest, the temperature will be low if the thermal system allows heat to leave efficiently, and the temperature will be high, if the thermal system impedes the flow of heat.
This general principle is valid regardless of the heat transfer mechanisms involved!
* * *
G&T focus enormous effort on making differentiations. They work hard to say that:
- Real greenhouses block heat loss by blocking convection, and that’s not the mechanism that is associated with the atmospheric greenhouse effect.
- Absorption and emission of radiation is different than reflection of radiation.
Yet, at the level of the principle offered above (less efficient heat loss ⇒ higher temperature), none of the distinctions G&T work so hard to clarify make the slightest difference.
* * *
Ok, so let’s look at a few specifics in G&T’s paper.
G&T claim to falsify an informal description of the greenhouse effect:
“The carbon dioxide in the atmosphere lets the radiation of the Sun, whose maximum lies in the visible light, go through completely, while on the other hand it absorbs a part of the heat radiation emitted by the Earth into space because of its larger wavelength. This leads to higher near-surface air temperatures.”
G&T’s response starts out (p. 39):
“Disproof: The first statement is incorrect since the obviously non-neglible [sic] infrared part of the incoming solar radiation is being absorbed (cf. Section 2.2).”
Section 2.2 of G&T asserts that 45% of the Sun’s energy comes in the form of infrared radiation, based on defining infrared as anything with a wavelength longer than 0.76 microns. Apparently, G&T assume “CO₂ absorbs infrared, so it must absorb a lot of the incoming solar radiation.” However, CO₂ only absorbs wavelengths greater than 4 microns, and less that 1% of the Sun’s energy is associated with these wavelengths. So, G&T’s “disproof” starts out with a false conclusion.
“The second statement is falsified by referring to a counterexample known to every housewife: The water pot on the stove. Without water filled in, the bottom of the pot will soon become glowing red. Water is an excellent absorber of infrared radiation. However, with water filled in, the bottom of the pot will be substantially colder.”
G&T are right about what happens in the kitchen, but are entirely wrong about what it means.
- Before water is added, heat loss from the bottom of the pot is mediated by a combination of thermal radiation and conduction/convection into the air. These are inefficient mechanisms, associated with slow heat loss and high thermal resistance, which causes the temperature of the pot to increase.
- After water is added, heat loss from the bottom of the pot is mediated by conduction/convection into the water. Water has much higher thermal conductivity than air, and is associated with much lower thermal resistance. Heat loss from the bottom of the pot is much more efficient in this case. Low thermal resistance causes the temperature of the pot to decrease.
- The enormous changes in the efficiency of conduction/convection completely overshadow any effects associated with what is happening to infrared radiation. This is a ridiculous example, utterly irrelevant to addressing the impact of absorption of long wavelengths.
Ironically, this example actually nicely demonstrates the abstract principle that I mentioned, which underlies the greenhouse effect:
- The temperature of a heat source is determined by two things: the power of the heat source, and the degree to which loss of heat is impeded. If you increase power or slow heat loss, temperature increases.
- The pot example illustrates this. With water, heat loss is efficient and the temperature is low. Without water, heat loss is inefficient, and the temperature is high.
- A similar pattern underlies the atmospheric greenhouse effect: greenhouse gases make heat loss inefficient, and this leads to a higher temperature.
G&T are so delighted with their example of a pot with and without water that they repeat this example in a later section (p. 74). Considering this example, along with their false conclusion that CO₂ absorbs a significant portion of incoming sunlight, they reach an additional false conclusion that CO₂ absorption and re-radiation might actually result in the ground becoming colder.
With regard to their current “falsification” they continue with another example:
“Another example would be the replacement of the vacuum or gas by glass in the space between two panes. Conventional glass absorbs infrared radiation pretty well, but its thermal conductivity shortcuts any thermal isolation.”
Once again, they claim to falsify the effects of infrared radiation being absorbed by comparing two situations in which the dominant difference is something other than what is going on with infrared radiation.
These examples are analogous to saying:
“it’s obvious that a candle can’t ever make a room lighter — just look what happens if you turn off an overhead light and light a candle instead — the room gets dimmer.”
The changing state of the overhead light completely dominates any effect of lighting a candle. A true test would only change the state of the candle, without changing the state of other lights. Yet, this is what G&T do in their examples. They throw in additional variables that obscure the effect they are purporting to examine.
Most of the examples G&T offer are like this, and are equally irrelevant to what they are purporting to demonstrate.
G&T dedicate 18 pages to discussing the physics of real greenhouses.
They seemingly fail to understand that the name “greenhouse effect” is a metaphor, not an assertion that the atmosphere functions in precisely the same way as a greenhouse.
They correctly point out ways that the atmosphere is not like a greenhouse, and entirely miss ways that the metaphor remains apt.
In both a greenhouse and in the Earth’s atmosphere, there is an ongoing stream of energy being supplied by sunlight. In both situations, some mechanism slows the loss of heat, and that slowing of heat loss results in an increase in temperature.
A greenhouse and the atmosphere differ in the details of how the slowing of heat loss functions.
- In a greenhouse, the slowing of heat loss is primarily in the form of convection being blocked. To a lesser extent, transmission of infrared thermal emissions are blocked, but this is a much less significant effect. It’s true that casual descriptions of how greenhouses work have often exaggerated the significance of infrared thermal emissions being blocked.
(G&T were pleased to point out this error in a few popular accounts. Yet, some of the popular accounts quoted by G&T (p. 43) show awareness of this issue prior to G&T going to so much effort to point it out. And, the prior IPCC 2007 report explained that greenhouses work by blocking convection (p. 115). G&T seem to overestimate the extent to which they were revealing anything not already widely known. Regardless, how actual greenhouses work has always been irrelevant to the way that climatologists analyze the atmosphere.)
- Infrared absorption and re-radiation plays a much larger role in slowing heat loss in the atmospheric greenhouse effect.
The detailed mechanism by which heat loss is slowed differs in the two cases. But, a greenhouse still offers a relevant analogy at a gross level, insofar as the slowing of the rate at which the heat from sunlight is lost leads to an increase in temperature.
G&T assert (p. 90) “The terms ‘greenhouse effect’ and ‘greenhouse gases’ are deliberate misnomers.” Leaving aside the impossibility of determining what is “deliberate,” this is not a fair slur. For an analogy to be useful or relevant does not require that the two things being compared be identical at every level of detail. G&T seem to me to be far too literally-minded for their own good.
There are certainly climatologists who wish the “greenhouse effect” had been given a different name, to spare them from the objections of all those who take metaphoric names so literally.
Disputing Energy Balance and notion of Average Temperature
G&T (p. 90) assert “Radiation and heat flows do not determine the temperature distributions and their average values.”
This begs the question: If not “radiation and heat flows,” what else could possibly “determine the temperature distributions and their average values”? From a perspective of the fundamental laws of physics, G&T’s assertion is preposterous. The laws of classical physics are ultimately deterministic, and “radiation and heat flows” are central to those deterministic laws.
G&T (p. 90) assert “Any radiation balance for the average radiant flux is completely irrelevant for the determination of the ground level air temperatures and thus for the average value as well.”
There is some complexity involved in addressing these matters rigorously. But, the assertion of “irrelevance” is unjustified and wrong.
As described in prior sections, energy balance diagrams for the Earth and its atmosphere depict the flows of energy between different realms.
Because energy is conserved, such diagrams tell us if total energy is stable, increasing, or decreasing within a given realm. Feedback mechanisms exist that require energy flows to balance, at least statistically. Whenever flows don’t balance, things get hotter or colder, and that shifts the flows towards balance. (Such balancing has been confirmed by measurements. Small imbalances in flows occur as climate shifts, warming oceans and melting ice, but energy continues to be conserved as long as these effects are accounted for.)
It is true that the “total thermal energy” of the Earth’s surface can have a somewhat complicated relationship to the “global average temperature,” Tavg, which can in turn have a somewhat complicated relationship to the “global effective temperature,” Teff, for purposes of determining the rate of thermal radiation which scales as Teff4.
It’s necessary to take at least some of these complexities into account, when using the “radiation balance for the average radiant flux” to determine “the ground level air temperatures and… the average value as well.”
But marginally complicated does not mean impossible or irrelevant.
Arthur P. Smith addresses these complications in his rebuttal of G&T’s work, as have other climate scientists long before G&T published their objections.
When addressing a 115-page rambling paper so steeped in misunderstandings, a full rebuttal might need to be of comparable length.
But, I think that’s enough for now.
I hope this examination of G&T’s work has been of value.
[This work was originally published as an Answer on Quora.]