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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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Has the greenhouse effect been falsified?

What the science says...

Select a level... Basic Intermediate

The greenhouse effect is standard physics and confirmed by observations.

Climate Myth...

Greenhouse effect has been falsified

"[T]he influence of so-called greenhouse gases on near-surface temperature - is not yet absolutely proven. In other words, there is as yet no incontrovertible proof either of the greenhouse effect, or its connection with alleged global warming.

This is no surprise, because in fact there is no such thing as the greenhouse effect: it is an impossibility.  The statement that so-called greenhouse gases, especially CO2, contribute to near-surface atmospheric warming is in glaring contradiction to well-known physical laws relating to gas and vapour, as well as to general caloric theory.' (Heinz Thieme)

At a glance

Did you know that in the late 1700s, astronomers calculated the Earth-Sun distance to within 3% of the correct average value of 149.6 million kilometres? That was an incredible feat for the time, involving painstaking measurements and some pretty serious number crunching, with no help from computers.

Why is that mentioned here, you might ask. It's because not long afterwards, in the 1820s, French physicist Jean Joseph Baptiste Fourier made another crucial calculation. He worked out that at this distance from the Sun, Earth should have been an uninhabitable iceball.

Fourier suggested there must be some kind of insulating 'blanket' within the atmosphere. By the end of that century, Eunice Foote and John Tyndall had proved him quite correct through their experiments with various gases and Svante Arrhenius quantified matters in 1896, even calculating the effect of doubling the concentration of CO2. They had it largely figured out all that time ago.

If you are still sceptical about the existence of a greenhouse effect on Earth, there's something you can do in order to double-check. Go to the moon.

Well, you don't have to go personally, thanks to remote sensing and lunar landings by both unmanned and manned craft. Such intrepid expeditions mean we have a stack of data regarding lunar properties. The moon is pretty much the same distance from the Sun as Earth, but the lunar atmosphere is so thin it may as well not exist at all. There's virtually nothing to inhibit heat transfer, in or out.

In addition, the Moon turns but slowly on its axis compared to Earth. While a mean Solar day here lasts 24 hours, on the Moon it lasts just under a month. You get the best part of a fortnight of relentless Solar heating followed by a similar period of cooling in the long lunar night. So what's the temperature?

In the vicinity of the Lunar equator, daytime temperatures eventually reach a boiling hot 120oC. During the lunar night, that temperature drops away to -130° C. No atmosphere so no greenhouse effect. All that heat accumulated in the long lunar day just shoots straight back out into space. Nights on Earth may be much shorter, but nevertheless in the absence of a greenhouse effect they would be brutal.

Our approximately Earth-sized near neighbour, Venus, closer to the Sun, is different again. It has a massive dense atmosphere mostly consisting of CO2 with a side-helping of sulphur dioxide. Surface atmospheric pressure on Venus is so great that on Earth you would need to go a kilometre down in the ocean to find similar values. The planet rotates very slowly on its axis so days and nights are even longer than on the Moon. But unlike the Moon, Venus is always a hot place. Its surface temperature is over 450oC, day or night. An extreme greenhouse effect maintains that heat.

Remember: no atmosphere, no greenhouse effect and unimaginably cold lunar nights - but the example of Venus shows you can also have too much of a good thing. Earth really is a Goldilocks planet.

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

Some climate science deniers dispute the existence of the ‘greenhouse effect’. This is where their arguments lurch from silly - to beyond silly. The greenhouse effect keeps the surface temperature of Earth approximately 33oC warmer than it would be if there were no greenhouse gases in the atmosphere. In other words, without the greenhouse effect, Earth would be effectively uninhabitable.

attacking the wrong greenhouse effect

Fig 1: The greenhouse effect is an analogy not meant as a scientific model of effect; hence, detractors have attacked the wrong model. (source: jg)

How do we know for sure this effect is real? The principle is demonstrated through basic physics, because a bare rock orbiting the Sun at the Earth-Sun distance (mean = 149.6 million kilometres) should be far colder than the Earth actually is. This was realised by Jean Joseph Baptiste Fourier in the 1820s, but the explanation why it was the case was not forthcoming for a few more decades. Fourier considered it to have something to do with the atmosphere having the properties of a kind of insulating blanket.

The existence of Fourier's hypothetical 'blanket' was confirmed by the experimental studies done by Eunice Foote and John Tyndall, working independently on either side of the Atlantic in the 1850s. Foote's results were announced at the 1856 meeting of the American Association for the Advancement of Science, and published in the American Journal of Science and Arts in the same year. The paper was entitled, ‘Circumstances Affecting the Heat of the Sun’s Rays’, with an excellent recent review by Ortiz and Jackon (2020). A key passage is as follows:

“The highest effect of the sun’s rays I have found to be in carbonic acid gas. An atmosphere of that gas would give to our earth a high temperature; and if as some suppose, at one period of its history, the air had mixed with it a larger proportion than at present, an increased temperature from its own action, as well as from increased weight, must have necessarily resulted.”

In his 1861 paper, “On the absorption and radiation of heat by gases and vapours, and on the physical connexion of radiation, absorption, and conduction” (PDF here), Tyndall stated:

“Now if, as the above experiments indicate, the chief influence be exercised by the aqueous vapour, every variation of this constituent must produce a change of climate. Similar remarks would apply to the carbonic acid diffused through the air; while an almost inappreciable admixture of any of the hydrocarbon vapours would produce great effects on the terrestrial rays and produce corresponding changes of climate.”

Tyndall had in his own words identified methane as an even more potent greenhouse gas than CO2. Later that century, Swedish scientist Svante Arrhenius put the numbers on the relationship between greenhouse gas concentrations and surface temperatures. He was able to calculate the effect of doubling the CO2 concentration in the air. The result was a globally-averaged figure of 5-6°C of warming, not that dissimilar to modern values.

Empirical Evidence for the Greenhouse Effect

We only have to look to our moon for evidence of what the Earth might be like, without an atmosphere and greenhouse effect. It's not as though we're short of data about our satellite. While the moon’s surface reaches 120oC (248oF) in direct sunlight at the equator during the long lunar day, when it gets dark the temperature drops down to a frigid -130oC (-202oF).

Since the moon is virtually the same distance from the sun as we are, it is reasonable to ask why at night the Earth doesn’t get as cold as the moon. The answer is that, unlike the Earth, the moon has no insulating blanket of greenhouse gases, because it has virtually no atmosphere at all. Without our protective atmosphere and its greenhouse effect, the Earth would be as barren as our lifeless moon. In the absence of the heat trapped overnight in the atmosphere (and in the ground and oceans) our nights would be so cold that few plants or animals could survive even a single one.

Conclusive evidence for the greenhouse effect – and the role CO2 plays – can also be seen in data from the surface and from satellites. By comparing the Sun’s heat reaching the Earth with the heat leaving it, both things we can measure with great accuracy, we can see that less long-wave radiation (heat) is leaving than arriving. Since the 1970s, less and less radiation is leaving the Earth, as the levels of CO2 and other greenhouse gases build up. Since all radiation is measured by its wavelength, we can see that the frequencies being trapped in the atmosphere are the same frequencies absorbed by greenhouse gases.

To conclude, disputing that the greenhouse effect is real is to attempt to discredit centuries of science, the laws of physics and indeed direct observation. Without the greenhouse effect, we would not even be here to argue about it.

Last updated on 26 November 2023 by John Mason. View Archives

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Comments 76 to 100 out of 179:

  1. Re: Henry justice (76)
    "It seems to me that the results may be more stunning with water vapor and we should reduce that too."
    You do realize, don't you, that to reduce the overall water content of the atmosphere you first have to reduce it's temperature? Water Vapor imbalances in the atmosphere equalize in approximately 8-9 days, and is highly dependent on the temperature of the air. Increasing concentrations of CO2 in the atmosphere are acting as a forcing, increasing the temperature of the air sufficient to also increase the humidity of the air by 4% (about the volume of Lake Erie). These increases in water vapor act as a feedback to further increase temperatures. The Yooper
  2. Henry, No, additional photons are not necessary for increased warming via greenhouse effect. All that is necessary is to slow the rate at which those photons can leave the atmosphere, which is precisely what GHG's do. You seem to be under the impression that a photon absorbed by a CO2 molecule disappears forever, and as there are only so many photons to be gobbled up, additional CO2 can't make things any worse. Greenhouse gases don't keep the photon, they re-radiate it in a random direction. The more CO2 in the atmosphere, the more likely the recently emitted photon wil be absorbed by yet another CO2 photon, or be radiated back toward the earth and absorbed by the surface. So while the total number of photons entering the planet's atmosphere has not changed, the number of photons exiting is reduced, hence more warming. Do you honestly find a website hosting a rather panicked rant about left-liberals, tax hungry democrats and evil socialists to be a source of good science?
  3. John Tyndall actually measured heating in carbonic acid solutions of various concentrations (CO2 dissolved in water) illuminated by gas flames. He didn't measure the absorbance of IR in purified gases. Knut Angstrom, an expert is solar radiation, proved that Arrhenius' calculations were wildly incorrect and based on an improper methodology. The fact that the Earth is warmer than the Moon simply proves that the oceans and atmosphere of Earth have an "atmospheric warming effect". It certainly doesn't prove the existence of a "Greenhouse Effect" due to CO2 or any other gas. All the planets(except Mercury which has no atmosphere) have an atmospheric warming effect that correlates directly with the pressure of the atmosphere. This is regardless of the actual atmospheric composition. The most important source of warming on Earth is the transfer of latent heat via evaporation and condensation. This is why coastal areas have far less variation between day and night temperatures compared with deserts. This is despite the concentrations of "GHGs" being the same. The satellite data simply shows that the Earth is radiating more heat. This can be caused by the upwelling of warm ocean water. It does not prove the existence of any Greenhouse Effect.

    [Daniel Bailey] Angstrom's error was in treating the atmosphere as a single layer. Later studies (of which they are legion) conclusively show that portion of his work to be in error. The GHG effects of CO2 are considered established fact. For a more in-depth discussion, see here, here and here.

    The remainder of your comment is in error. So I recommend that you also read Newcomers, Start Here and then learn The Big Picture. I also recommend watching this video on why CO2 is the biggest climate control knob in Earth's history.

  4. I'm seeing references to a paper by a Joseph Postma, also denying any greenhouse effect. His argument boils down to this: 1. Thermodynamics says the effective black body temperature of the earth is -18C, and this is matched by observation from space. 2. We observe much balmier temperatures at the earth's surface in practice. 3. The Greenhouse Theory says the difference is down to the greenhouse effect. 4. Postma observes that the temperature of -18C occurs at 5km altitude: "This altitude is found at about 5km in height above the ground surface by observation. " 5. He calculates from more thermodynamic theory (the adiabatic lapse rate) that we should therefore expect the temperature at the surface of the earth to be 14.5C. Voila! No need for a greenhouse effect. The blunder, of course, is that he offers no explanation for the -18C line being at 5km. And the explanation is ... the greenhouse effect! He also makes this confusion on thermodynamics, which I've seen elsewhere: "something which is cool cannot transfer heat to something which is warm". Clearly he is thinking of net transfer, but that's not how he uses this principle.
  5. I don't believe it is generally agreed that falling temperatures with increasing altitute are the result of the GHE. The term is actually called the adiabatic lapse rate. Howere, I think this needs more consideration. For instance this paper by Verkley and Gerkema is relevant: “A column of dry air in hydrostatic equilibrium ….. bounded by two fixed values of the pressure, and the question is asked, what vertical temperature profile maximizes the total entropy of the column? Using an elementary variational calculation, it is shown how the result depends on what is kept fixed in the maximization process. If one assumes that there is no net heat exchange between the column and its surroundings—implying that the vertical integral of the absolute temperature remains constant—an ISOTHERMAL profile is obtained in accordance with classical thermodynamics and the kinetic theory of gases” http://www.nioz.nl/public/fys/staff/theo_gerkema/jas04.pdf If that would not be the case, it would be possible to build a machine that makes mechanical energy from a single source of heat. This goes against the 2nd law of thermodynamics. The natural intuition that the temperature must be warmer at the bottom, because molecules gain energy, when falling, is wrong because it’s exactly compensated by another phenomenon: Those molecules that have little energy cannot go up as well as those with more energy. This is not to deny that the sudden imposition of a gravitational field on a column of gas would indeed set up a temperature gradient. It would – but it wouldn’t persist. It would quickly be homogenized and the column would become isothermal. So if a column of gas behaves this way would a GH free atmosphere behave the same way too? Without the driving force of IR radiation from the upper reaches of the atmosphere there would be very little net heat flux in our column of air. There would be no re-radiation of course and very little convection. A GH free atmosphere would be very different from our present one and approximately much more closely to an isothermal state. So if this is the case, then we can show that the GHE has not been falsified simply by climbing a mountain and noticing that it does indeed get colder.
  6. Following from my earlier comment about our state MP who advocates against the science of climate change, here he is demonstrating that he's not just a politician but a brilliant scientist.
  7. Tristan, if he is as bright as you suggest, then I'm sure he must have an explanation as to why there is so much more downwelling IR radiation reaching the surface than what the Sun emits. That is an easy, reliable, confirmed over and over, direct, real world observation, in total contradiction with the little experiment you link above. So allow me to be a little skeptical. Where does all that IR come from?
  8. I'm certain he has an explanation. They always do.
  9. I'm certain he has an explanation. They always do.
    Don't they just? And the operative word is "an". The explanation doesn't need to be the correct one, because the intent here is to sow fear, uncertainty, and doubt. Purely and simply. Richard Pearson's target audience is the unsure, non scientifically-educated swinging voters who form a large proportion of his and his colleagues' voting constituency. Sadly, most of them are not as cooly logical as Philippe, and frustratingly there never seems to be a simple way of getting across perceptive points such as his. Pearson doesn't need to be right; he just needs to be convincing.
  10. There is a basic flaw in the paragraph Empirical Evidence for the Greenhouse Effect We only have to look to our moon for evidence of what the Earth might be like without an atmosphere that sustained the greenhouse effect. While the moon’s surface reaches 130 degrees C in direct sunlight at the equator (266 degrees F), when the sun ‘goes down’ on the moon, the temperature drops almost immediately, and plunges in several hours down to minus 110 degrees C (-166F). The flaw is that the cooling rate on the Moon is significantly slower than your article suggests and even NASA state :- “During lunar day, the lunar regolith absorbs the radiation from the sun and transports it inward and is stored in a layer approximately 50cm thick. As the moon passes into night, the radiation from the sun quickly approaches zero (there is still a bit of radiation from the earth) and, in contrast with a precipitous drop in temperature if it was a simple black body, the regolith then proceeds to transport the stored heat back onto the surface, thus warming it up significantly over the black body approximation.” Contrast this with the fact that Earth's atmosphere obviously reduces the heating "power" during the day and you have empirical evidence that atmospheres reduce surface heating of planets - not the reverse. I expect this comment to be deleted but it was enjoyable posting it. (-snip-).

    [DB] Sloganeering snipped; moderation complaints struck out.

    All parties please note: Rosco's Moon comparison has been previously rebutted, most recently here. As such, it is to be treated as sloganeering and subject to moderation.

  11. Rosco, your remark is unlikely to be deleted and your enjoyment will probably be brief. :-) Starting with: based on Rosco's analysis, may we conclude that Earth's moon has an atmosphere comprised of regolith?
  12. doug_bostrom - it is not my analysis - I have quoted NASA. (-snip-).
    Response: [DB] All parties please note: Rosco's Moon comparison has been previously rebutted, most recently here. As such, it is to be treated as sloganeering and subject to moderation/snipping.
  13. Rosco - Your comments here are interesting, but perhaps not in the fashion you intended. Rather, they show what errors occur when you don't take all factors into account. Convection and latent heat indeed cool the earth, pushing heat into the upper atmosphere where it can be radiated. If the atmosphere lacked convection, we could readily expect temperatures perhaps another 40-45°C warmer than currently exist. We are indeed fortunate that convection exists, that atmospheres become unstable and convect with warming, that evaporative processes move energy away from the surface. But without the greenhouse effect (in a Gedankenexperiment consideration, as certainly other things would change with such a physical modification), without significant radiation from high in the cold atmosphere rather than the warmer surface, the Earth would be ~33°C colder than current temperatures, on the order of -16°C to -18°C. Heating and cooling of the lunar regolith are indeed factors in the moon's average temperature. But that average is quite a bit cooler than the Earth's temperature (in fact, if the Moon had an equivalent atmosphere, it would be warmer, as the albedo of the Earth is rather higher - 0.3 as opposed to the Moon's 0.12). If you take all of these factors into account, rather than focusing on a single factoid (defined as a piece of information smaller than a useful fact), the radiative greenhouse effect has just the influence predicted by the physics of spectroscopic absorption, emission, and the atmospheric lapse rate. And that's ~33°C warmer than we would be without the greenhouse effect if that was the only change.
  14. Rosco, the mean surface temperature of the Moon at the equator is approximately 206 degrees Kelvin. For comparison, the mean daily temperature in August (the coldest month) at Vostok Station (the coldest place on Earth)is 205 degrees Kelvin. In other words, the means surface temperature of the hottest location on the Moon is the same as the mean surface temperature of the coldest location on Earth when it is at its coldest. The mean annual temperature at Vostok Station is actually just over 10 degrees K warmer than the mean annual temperature of the Moon at the equator. As it happens, the Moon has a lower albedo than the Earth, so all else being equal, it should be warmer than the Earth, yet it is colder. Can you explain how your theory that the Earth's atmosphere cools the Earth is compatible with these facts?
  15. Rosco, what happens at the top of the atmosphere-- where convection ends? Also, you need to do some research on why the ISS employs radiators. Start with something simple, like the Apollo spacecraft. Try here: history.nasa.gov.
  16. Roscoe, I see no conflict between your quote from NASA and the article. According to you, the article states "the temperature drops almost immediately, and plunges in several hours down to minus 110 degrees C". NASA says "in contrast with a precipitous drop in temperature if it was a simple black body, the regolith then proceeds to transport the stored heat back onto the surface, thus warming it up significantly over the black body approximation" A black body would drop to -110C almost immediately. If it takes "several hours" as the article says, that is "significant warming" as NASA says. The problem is you are reading the articles incorrectly. Perhaps you should read the article again to clarify the data. Just because you do not understand the data does not mean everyone else does not understand it also.
    Response: [DB] All parties please note: Rosco's Moon comparison has been previously rebutted, most recently here. As such, it is to be treated as sloganeering and subject to moderation.
  17. Michael Sweet @91, if no heat was stored in the Moon's regolith, temperatures would fall to 2.7 degrees K at night, that being the temperature of the cosmic background radiation. The near constant night time temperature contrasts sharply with the presumed behaviour of a "simple black body". (Of course, there is nothing in the nature of black bodies per se from retaining heat, and therefore not instantaneously matching incoming radiation with outgoing radiation with the same power.) As a matter of interest, I have googled Roscoe's quote and found it on several denier documents without citation. Therefore, the attribution of the quote to NASA must be considered suspect until the source of the quote is cited and linked to.
  18. As an interesting thought experiment - would a cubic blackbody have a different temperature to a spherical one ?
    Response: [DB] Please note that Rosco has recused himself from further participation in this venue (essentially a meltdown/temper tantrum).
  19. Well, Rosco, (-snip-). There is plenty of information available on the subject, from NASA and other sources, with which you are obviously not familiar. I will not bother linking anything because, if you have any sincerity, you will find it quite easily, no help needed. Your argument is not well constructed, it is a delirious case of Dunning-Krueger effect. The fact that you feel that you can come here and lecture not only on planetary science but also on moral principles is laughable. The kicker was putting together the idea of a well thought out argument and that of a square planet. Thanks for the entertainment. (-snip-).
    Response: [DB] References to deleted comments snipped by request.
  20. To any casual reader who wanders by and reads Rosco's approach to science... This exemplifies why it is important to do the math, and to actually quantify the effects in question. It is very easy to "consider" and to do "thought experiments." With a wave of the hand, the dark side of the moon has 720 hours to cool and look, a sweltering motorcycle shop needs fans. It's so easy when you do everything by analogy, with none of that highfalutin mathematics and calculations and fancy numbers to get in the way. Don't do science by thought experiment and "obvious" conclusions. Run the numbers. All of them, not just the ones that conveniently seem to demonstrate the point that you'd dearly love to be true.
  21. Further to Sphaerica's comment, I might add that if, like me, you don't have the skill set to do the maths yourself, link to someone who does.
  22. Adding to Sphaerica's comment: Frequent errors in these discussions are attempts to argue back from analogies. Analogies are useful "forward" explanations - complex system A is (in part) analogous to a more familiar system B (to portions thereof), and if your listener has context on B that can be useful in explaining relationships in A as "like" those in B. Energy balance in the climate is like a dam in a river, or the radiative greenhouse effect is like a blanket, for example. But those analogies cannot be used for "backward" testing, as there are portions of the complex system A that are not mapped in B, and portions of B that have no corresponding element in A - and assuming that the mapping is 1:1 is an error. Hence arguments such as from motorcycle shops to lunar regolith, or for that matter many of the "2nd law" or "Slayers" objections to the greenhouse effect, are simply meaningless nonsense, handwaving. An analogy is a useful explanation. But testing theories about complex systems needs to be done in those frameworks, using numbers, using math, with the actual relationships - not in a partially mapped analogy that is not the system in question.
  23. There is a very simple explanation for the 33 degrees extra temperature on planet earth and it is basic high school science from around 10th grade. PV=nRT ,Avagadro number and all that.Pressure is proportional to temperature. This also explains why temperatures fall(1 degree per 200 metres) with altitude and rise in the deep sub sea level areas of the earth. As for planet Venus, apart from being closer to the sun, pressures are 92 times that of Earth at the surface. As on Earth,temperatures fall with altitude. You would think that temperatures would be more even in the atmosphere of Venus if the "runaway greenhouse" were for real. The same effect I think occurs on Jupiter- the outer gas is cold, but deeper in the atmosphere as the pressure builds, it is considerably warmer. Think how refrigerators work- they compress the refrigerant gas, which get warm. The heat is radiated out, then when the pressure is released, the gas cools to allow us to have that icy cold beer on a stinking hot day. I lay down the gauntlet for some physicist out there with more brains than myself to check this simple hypothesis and gain immortality and cudos.
  24. "For every complex problem there is an answer that is clear, simple, and wrong." High treason, your hypothesis fails to explain why the stratosphere warms with altitude. Perhaps more reading is in order?
  25. JasonB @99, he also fails to explain why temperatures fall with increasing pressure as you go deeper into the ocean. He tries to conceal this by asserting that:
    "PV=nRT ,Avagadro number and all that.Pressure is proportional to temperature. This also explains why temperatures fall(1 degree per 200 metres) with altitude and rise in the deep sub sea level areas of the earth."
    But, of course, temperatures do not rise in the ocean abyss except at the sites of volcanic vents. Even there, while the water emitted from the vent may be as warm as 400 C, within meters of the vent the ambient temperature is a frigid 2 degrees C. Worse for high treason, the ideal gas law alone is not sufficient to explain the temperature profile of the troposphere. You also need to employ the laws of thermodynamics, the universal theory of gravitation, and the assumption that convection is the main form of heat transfer within the troposphere. And worst of all for high treason, he forgets is earliest lessons in algebra. Taken together, basic physical law explain the approximate -6.5 C per kilometer altitude temperature profile of the troposphere; but that only gives you a line with a slope. Knowing only the slope, you cannot deduce the intersection with the x-axis, ie, the surface temperature. Not only has he got his high school science wrong - he can't even get his primary school maths right.

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