Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.


Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup


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.

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Bluesky Facebook LinkedIn Mastodon MeWe

Twitter YouTube RSS Posts RSS Comments Email Subscribe

Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...

New? Register here
Forgot your password?

Latest Posts


Has the greenhouse effect been falsified?

What the science says...

Select a level... Basic Intermediate

The atmosphere of the Earth is less able to absorb shortwave radiation from the Sun than thermal radiation coming from the surface. The effect of this disparity is that thermal radiation escaping to space comes mostly from the cold upper atmosphere, while the surface is maintained at a substantially warmer temperature. This is called the "atmospheric greenhouse effect", and without it the Earth's surface would be much colder.

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)

Most participants in climate debates can agree that the atmosphere's capacity to interact with thermal radiation helps maintain the Earth's surface temperature at a livable level. The Earth's surface is about 33 degrees Celsius warmer than required to radiate back all the absorbed energy from the Sun. This is possible only because most of this radiation is absorbed in the atmosphere, and what actually escapes out into space is mostly emitted from colder atmosphere.

This absorption is due to trace gases which make up only a very small part of the atmosphere. Such gases are opaque to thermal radiation, and are called "greenhouse gases". The most important greenhouse gases on Earth are water vapor and carbon dioxide, with additional contributions from methane, nitrous oxide, ozone, and others. If the atmosphere was simply a dry mix of its major constituents, Oxygen and Nitrogen, the Earth would freeze over completely.

Observing the greenhouse effect in action

The simplest direct observation of the greenhouse effect at work is atmospheric backradiation. Any substance that absorbs thermal radiation will also emit thermal radiation; this is a consequence of Kirchoff's law. The atmosphere absorbs thermal radiation because of the trace greenhouse gases, and also emits thermal radiation, in all directions. This thermal emission can be measured from the surface and also from space. The surface of the Earth actually receives in total more radiation from the atmosphere than it does from the Sun.

The net flow of radiant heat is still upwards from the surface to the atmosphere, because the upwards thermal emission is greater than the downwards atmospheric backradiation. This is a simple consequence of the second law of thermodynamics. The magnitude of the net flow of heat is the difference between the radiant energy flowing in each direction. Because of the backradiation, the surface temperature and the upwards thermal radiation is much larger than if there was no greenhouse effect.

Atmospheric backradiation has been directly measured for over fifty years. The effects of greenhouse gases stand out clearly in modern measurements, which are able to show a complete spectrum.

IR spectrum at  the North Pole
Figure 1. Coincident measurements of the infrared emission spectrum of the cloudfree atmosphere at (a) 20km looking downward over the Arctic ice sheet and (b) at the surface looking upwards. (Data courtesy of David Tobin, Space Science and Engineering Center, University of Wisconsin-Madison. Diagram courtesy of Grant Petty, from Petty 2006).

When you look down from aircraft at 20km altitude (Fig 1a), what is "seen" is the thermal radiation from Earth that gets out to that height. Some of that radiation comes from the surface. This is the parts of the spectrum that follow a line corresponding in the diagram to about 268K. Some of that radiation comes from high in the atmosphere, where it is much colder. This is the parts of the spectrum that follow a line of something like 225K. The bites taken out of the spectrum are in those bands where greenhouse gases absorb radiation from the surface, and so the radiation that eventually escapes to space is actually emitted high in the atmosphere.

When you look up from the surface (Fig 1b), what is "seen" is thermal backradiation from the atmosphere. In some frequencies, thermal radiation is blocked very efficiently, and the backradiation shows the temperature of the warm air right near the surface. In the "infrared window" of the atmosphere, the atmosphere is transparent. In these frequencies, no radiation is absorbed, no radiation is emitted, and here is where IR telescopes and microwave sounding satellites can look out to space, and down to the surface, respectively.

The smooth dotted lines in the diagram labeled with temperatures are the curves for a simple blackbody radiating at that temperature. Water vapor has complex absorption spectrum, and it is not well mixed in the atmosphere. The emissions seen below 600 cm-1 are due to water vapor appearing at various altitudes. Carbon dioxide is the major contributor for emission seen between between about 600 and 750 cm-1. The patch of emission just above 1000 cm-1 is due to ozone.

The term "greenhouse"

The term "greenhouse" was coined for this atmospheric effect in the nineteenth century. A glass greenhouse and an atmospheric greenhouse both involve a physical barrier that blocks the flow of heat, leading to a warmer temperature below the barrier. The underlying physics is different, however. A glass greenhouse works primarily by blocking convection, and an atmospheric greenhouse works primarily by blocking thermal radiation, and so the comparison is not exact. This difference is well understood and explained in most introductions to the subject. Where confusion arises, it is usually the glasshouse that is improperly described, rather than the atmospheric greenhouse effect.

The enhanced greenhouse effect

The greenhouse effect itself has always been an important effect on Earth's climate, and it is essential for maintaining a livable environment. Without it, the surface would rapidly freeze.

The existence of a greenhouse effect itself should not be confused with changes to the greenhouse effect. Global warming in the modern era is being driven by increasing concentrations of greenhouse gases in the atmosphere, which leads to an enhanced greenhouse effect. This is covered in more detail as a separate argument: How do we know more CO2 is causing warming?

Intermediate rebuttal written by sylas

Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial


Last updated on 11 July 2015 by MichaelK. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.


1  2  3  4  5  6  7  8  Next

Comments 1 to 25 out of 179:

  1. In this thread user miekol is asked by the moderator to post a question about this article in this thread. I thought I'd "jump the gun" and post a rebuttal now! The article states that O2 and N2 are, despite claims by "warmists", Infra-red active and links to some IR plots. These plots are, in fact all due to molecules made up of different isotopes. Thus there are plots for 16O-17O, 16O-18O and 17O-18O and one for 14N-15N, but none for the symmetric counterparts. Note that for some of the plots the isotope details have been removed. Because these isotopic variants are very nearly symmetric, the absorption is weak (see the very small numbers on the vertical axis). So these isotopic variants make up a tiny percentage of the gases, and the small percentage that do absorb only very weakly. Moreover the O2 and N2 absorptions don't match the frequencies that earth emits at, so there is nothing in "earth-light" for these gases to absorb. Later in the page they state that because O2 and N2 melt at a lower temperature, they are "most sensitive to heat absorption". This is completely incorrect. The melting points of substances relate to the strength of the forces between molecules, which ultimately comes down to the distribution of positive and negatives charges within the molecule. H2O has a negative "end" (the Oxygen) and a positive "end" (the Hydrogen) and this makes a powerful attachment between the molecules. Symmetric molecules like O2 have much weaker attractions and so take less energy to melt and vapourise
  2. Which shows that O2 and N2, 99% of the atmosphere, are more sensitive to heat absorption than CO2, 0.0385% of the atmosphere. Also weight for weight O2 and N2 have a higher heat capacity than CO2 which means that if the atmosphere consisted of 50% O2 and N2 and 50% CO2, then the CO2 half of the atmosphere would still be less important with regards atmospheric warming. But the atmosphere is not 50% N2/O2 and 50% CO2, it is 99% N2/O2 and 0.0385% CO2. Ultimately the fallacious assertions in support of the bogus "greenhouse effect" depend entirely on the ridiculous notion that the atmosphere is heated bottom-up by OLR (outgoing Long-wave radiation). This in-turn requires that the atmosphere is completely transparent to incoming full spectrum electro-magnetic radiation, a large percentage of which is IR. Both of which are false. In the following links there is finally incontrovertible proof that the atmosphere is radiatively heated from the top-down by incoming electromagnetic radiation from the Sun. This fact destroys the "Greenhouse Effect" hypothesis which stipulates, bottom-up atmospheric heating via outgoing infra-red. "The Diurnal Atmospheric Bulge, giant 1200º bulge of rapidly heated and expanding gases circling the Globe 24/7." "Diurnal Atmospheric Bulge, incontrovertible evidence of massive top down radiative heating. "
  3. Will, if there's no Greenhouse Effect, why doesn't the Earth freeze over at night?.
  4. Another question Will - if there's no Greenhouse Effect, why was it warmer in Earth's distant past at a time of reduced solar luminosity?.
  5. Will writes: Ultimately the fallacious assertions in support of the bogus "greenhouse effect" depend entirely on the ridiculous notion that the atmosphere is heated bottom-up by OLR (outgoing Long-wave radiation). This in-turn requires that the atmosphere is completely transparent to incoming full spectrum electro-magnetic radiation, a large percentage of which is IR. Either you're forgetting the inverse-square law, or you're confused about the distinction between "near infrared" and "thermal infrared" wavelengths. A large percentage of the total downwelling solar irradiance is in the near-infrared range, but the atmosphere is mostly transparent in this part of the spectrum. Only a very small fraction of solar irradiance is in the thermal infrared region. If we look just at thermal infrared radiation, how much of the radiant flux in the atmosphere is from the sun and how much is from the earth? Obviously, the sun is much hotter ... but it's also much further away. Thus, virtually all the IR radiation in the atmosphere is coming from the earth, not the sun: From Science of Doom The yellow curve at the left is the blackbody radiation curve for the sun at a temperature of 5780K and a distance of 150 million km. The variously colored curves on the right are blackbody radiation curves for the earth at various normal earth temperatures. Note, first, that the Y axis is log-scaled. Note, second, that in the thermal part of the spectrum (greater than 3 micrometers) the area under the "earth" curves is much, much larger than the area under the "sun" curve. Bottom line, the sun heats the earth via visible and near-infrared radiation. The earth emits long-wave (thermal infrared) radiation. Increasing the concentration of greenhouse gases in the atmosphere traps more of that long-wave radiation and raises the temperature of the earth system.
  6. Will, the "heat capacity" issue is irrelevant, too. CO2, methane, CFCs, etc. absorb longwave IR radiation, but they then transfer that heat to the rest of the atmosphere via collisions with other atmospheric molecules (roughly a billion collisions per second per molecule).
  7. #5 Ned at 21:26 PM on 25 August, 2010 A large percentage of the total downwelling solar irradiance is in the near-infrared range, but the atmosphere is mostly transparent in this part of the spectrum That's how transparent it is.
  8. Sorry but these statements are nothing but semantics. The Diurnal Atmospheric Bulge is incontrovertible proof of massive violent top-down atmospheric heating. Please follow the link and read the paper. A greenhouse with a full canopy of leaves completely shielding the ground from direct Sunlight still functions normally. More proof that air is heated by incoming full spectrum electro-magnetic radiation and NOT by OLR. Therefore the "greenhouse effect" hypothesis is false. Ned, Air is rated as one of the top insulators of all substances. That means that air is a very poor conductor of energy compared to most substance. In fact it is one of the poorest conductors of energy there is. What are you trying to describe in your last statement? Conduction or Radiation?
  9. Berényi Péter This diagram of absorption bands is interesting for what it doesn't show. 79% of the atmosphere is completely missing.
  10. These comments are a nice example of the problems I have raised many times on this site, most recently here. That is, we often get comments on this site from the more serious "skeptics" accusing us of wasting time on straw-man arguments and of rebutting claims that no one really believes. So ... here we have another commenter claiming that the atmosphere is directly heated by solar irradiance "top-down" and that the greenhouse effect does not exist. I could, of course, do what so many of us supporters of mainstream science have done over and over again, and patiently work on responding to these claims, explaining to Will why he misunderstands the physics of radiation in the atmosphere. It would be nice, though, if some of those supposedly serious, reasonable skeptics would join in and help answer Will's claims. If that were to happen, it might help me believe that there really are "skeptics" who are serious about science. So far, the only resident "skeptic" commenter to speak up has been Berényi Péter ... who quibbles over my use of the word "transparent" but is apparently unable or unwilling (or perhaps too busy) to contribute anything more directly relevant to addressing Will's questions. Is there anyone on the "skeptic" side here who understands what's wrong with Will's claims and is actually willing to say so? Or, once again, will the job of explaining Will's errors be left up to the rest of us? Of course, this isn't the most recent or active thread, so I suppose it's possible that many people might not notice these comments immediately.
  11. Will, if air is such a poor conductor of energy, how can the atmosphere maintain its cool temperature in the face of (warming) radiation from any direction, sun or earth. Given that it is a poor conductor, the only way for the atmosphere to cool must be by, you guessed it, radiation at the top of the atmosphere. If it's radiating out at the top of the atmosphere, surely the molecules comprising the atmosphere would also be radiating all the way through the atmosphere. Unless there are GPS guided molecules that can work out where they are to start radiating in only one place?
  12. adelady: You are correct, it is of course radiation. Which is why I asked Ned to clarify if he was describing conduction or radiation. Assuming he even knows of course. Ned has opted to go on the attack instead of answering the question. I repeat to Ned, please follow the links and read my article. Then explain how an area with a circumference of 25% of the entire surface of the atmosphere can bulge up to an altitude of more than 600 km altitude under the solar point at around 2 pm in the sky, yet at 4 am on the dark side of the Earth this bulge completely collapses bellow the Mesosphere at under 90 km, if the atmosphere is so transparent to incoming full spectrum electro-magnetic energy.
  13. Of course the thermosphere and to a lesser extent the mesosphere are heated by the sun, mostly via UV absorption. But they're not that far from vacuum -- less than 1% of the mass of the atmosphere. And this is completely irrelevant to the greenhouse effect. There's simply no connection whatsoever. The situation in the troposphere -- the layer of the atmosphere closest to the surface, including most of the mass of the atmosphere -- is entirely different. Longwave radiation from the surface is absorbed by molecules of CO2 and other greenhouse gases, which in turn heat the more numerous N2 and O2 molecules kinetically, via intermolecular collisions. Thus, the entire mass of a given "parcel" of the atmosphere shares a single temperature -- you don't have different temperatures for CO2, O2, N2, etc. CO2 and the other greenhouse gases then radiate in all directions. Thus, the presence of GHG molecules warms the troposphere, and increasing the concentration of those molecules increases the efficiency of this warming. Keep in mind that the vast majority of solar irradiance is at relatively short wavelengths (visible and near-infrared) where atmospheric transmittance is relatively high. The solar flux at thermal IR wavelengths (over 3 micrometers) is minuscule in comparison to the terrestrial outgoing thermal IR flux. If you would like a good overview of the physics of the greenhouse effect, I would highly recommend the series of posts on "CO2: An Insignificant Trace Gas?" over at Science of Doom. Hope this helps.
  14. Will - There's definitely heating from the sun involved in atmospheric expansion. Looking at the energy balances from Trenberth 2009 roughly 78 W/m^2 of sunlight are directly absorbed by the atmosphere. Another 161 get absorbed by the ground/water. However, what's emitted by the top of the atmosphere (as LW radiation) is ~169 W/m^2 - partly re-emission of atmospheric energy, mostly emission from ground/water thermal energy that has percolated up through multiple absorption/emission events. And the temperature profile of the atmosphere shows warming of the troposphere and cooling of the stratosphere - if this was all top-down warming you would see a hot stratosphere and colder troposphere, relatively speaking. The observed temp profile is one of the fingerprints of the greenhouse gas effect. So yes, some top-down heating does occur. But it's mostly bottom-up, as most of the solar irradiation goes through the atmosphere to the ground, only returning as IR. I would say that the diurnal bulging of the atmosphere is due to the atmosphere warming - because days are warmer than nights. But the temp profile clearly shows that it's warming from the bottom (IR), not the top (solar).
  15. Will - on your note that 79% of the atmosphere is completely missing: I assume you mean N2? Nitrogen doesn't absorb/emit in the IR, and in fact most of it's absorption is in the UV. Hence it's usually not shown on most charts of greenhouse gases - it's irrelevant to the IR spectra.
  16. Ned: The Thermosphere is not a sphere it is a bulge. The Diurnal Atmospheric Bulge and the Thermosphere are one and the same. The Diurnal Atmospheric Bulge (Thermosphere) is caused entirely by incoming EMR. I never said there was a connection between the "greenhouse effect" and the Thermosphere. I said there is no "greenhouse effect". I have proven this with experimental verification on my website at the following link: "The Diurnal Atmospheric Bulge, giant 1200º bulge of rapidly heated and expanding gases circling the Globe 24/7." KR: The atmosphere (air) is a excellent insulator and therefore a poor conductor. It exhibits various temperature gradient inversions. Partly because it is such a good insulator and partly because it is heated from the top-down by incoming EMR. All mysteries explained. Which way up is the temperature gradient in a greenhouse? Like I said before, a greenhouse still functions perfectly well with a full canopy of leaves shielding the ground completely from direct sunlight. 40-50% of the incoming sunlight hitting the leaves is locked in by photosynthesis and the rest is reflected as short-wave. No direct sunlight reaches the ground yet the greenhouse still warms that same as an empty one would. Where is the "greenhouse effect" bottom-up warming in this scenario? When your theory generates more questions than it answers, this is a clue that you are traveling away from the truth. When your theory is still awaiting experimental verification after 200 years . . . . . ?
  17. Will, the troposphere is mostly heated from below, not from above, as KR notes above. The use of a glass greenhouse to illustrate the greenhouse effect is only appropriate at a coarse "end result" level, not as an actual model of how the CO2-induced GHE actually works. But in any case, the sunlight entering a (glass) greenhouse warms all dark surfaces within the space (floor, plant leaves, whatever). It doesn't significantly provide any direct warming of the air molecules inside the greenhouse. The air is warmed by contact with the various surfaces that are absorbing sunlight. Photosynthetic efficiency for most plants is less than 2%, and less than 10% in virtually all cases. Most of the sunlight absorbed by plant leaves just raises their temperature (directly) and that of the air around them (indirectly). Finally, there's experimental verification of the CO2 greenhouse effect -- see here or here (and continue on to parts two and three as well).
  18. And, of course, Figure 1 in the very post at the top of this thread is direct evidence of the CO2 greenhouse effect.
  19. Will, please look up the definition of thermosphere. It is a layer of the atmosphere. The atmosphere is a poor conductor only relative to other substances (e.g., solid metal). That is irrelevant to this topic. What is relevant is the atmosphere's absolute conductivity. In a greenhouse or anywhere else, sunlight hitting leaves heats the leaves. Go find a plant that is exposed to sun. Put your hand on a leaf that is exposed to sun and compare its temperature to that of a leaf that is in the shade. You are correct that some of the sunlight hitting the leaf is consumed by photosynthesis, and that some is reflected, but some is absorbed as heat.
  20. #15 KR at 01:40 AM on 26 August, 2010 Nitrogen doesn't absorb/emit in the IR, and in fact most of it's absorption is in the UV True. It has no "greenhouse effect" whatsoever. Still, if you removed half the nitrogen from the atmosphere, the Earth would freeze over completely down to the very bottom of oceans. And if you raised its quantity twofold, global temperatures would go up by 40°C, cooking all of us for good. That much about the alleged 33°C warming from GHGs.
  21. Will - An important point in the atmospheric greenhouse effect (which as Ned notes is not the same thing as a glass greenhouse in operation) is that GHG's aren't opaque to IR. They absorb thermal IR from the ground as per Berényi's post, and emit it again spherically distributed. This causes half of what they absorb to go back to the ground, which shows up clearly in the notches of the first chart of Figure 1.
  22. Berényi - "...if you removed half the nitrogen from the atmosphere, the Earth would freeze over completely...". Really? Are you talking about the lapse rate? If's just the lapse rate you could swap nitrogen for argon or krypton (distinctly NOT greenhouse gases) with no effect. I would love to see your reasoning (and math) for this non-GHG effect, as I don't see how that would occur.
  23. Ned I think I said EXPERIMENTAL verification! Please don't "Science of Doom" me. As for Photosynthetic efficiency which is just one part of the effect I'm referring to, 2% is a stab in the dark. While it is claimed that crops such as wheat may achieve low efficiency of between 1-4%, sugar cain can achieve 7%, but photosynthesis is just one process plants use energy for. Oxygen production is another. The point is that very little of the energy is converted to IR compared to say concrete slabs or Earth. At my site you find direct reproducible experimental evidence that pure CO2 causes less warming than ordinary air. Tom Dayton Wikipedia, please ? ! Go to the two links I have given above. The DIurnal Bulge has been deliberately hidden in plain view by renaming it as the Thermosphere. On the dark side of the Earth there is no Thermosphere. Therefore the Thermosphere is not a layer, it is a giant bulge on the sunny side.
  24. KR Glass is not opaque to IR either. See here: "The Diurnal Bulge and the Fallacies of the Greenhouse Effect."
    Response: To save us the trouble of editing your links, be sure not to include an extra space and line-break inside the quotation marks with the link URL. For example, use
    <img width="450" src="http://image_url/">
    rather than
    <img width="450" src="http://image_url/
  25. #22 KR at 04:18 AM on 26 August, 2010 If's just the lapse rate you could swap nitrogen for argon or krypton (distinctly NOT greenhouse gases) with no effect No, you could not. These are monatomic gases (unlike nitrogen), therefore their adiabatic index is not the same (5/3 vs. 7/5). Dry adiabatic lapse rate would be higher.

1  2  3  4  5  6  7  8  Next

Post a Comment

Political, off-topic or ad hominem comments will be deleted. Comments Policy...

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.

Link to this page

The Consensus Project Website


(free to republish)

© Copyright 2024 John Cook
Home | Translations | About Us | Privacy | Contact Us