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Is the CO2 effect saturated?

What the science says...

Select a level... Basic Intermediate Advanced

The notion that the CO2 effect is 'saturated' is based on a misunderstanding of how the greenhouse effect works.

Climate Myth...

CO2 effect is saturated

"Each unit of CO2 you put into the atmosphere has less and less of a warming impact. Once the atmosphere reaches a saturation point, additional input of CO2 will not really have any major impact. It's like putting insulation in your attic. They give a recommended amount and after that you can stack the insulation up to the roof and it's going to have no impact." (Marc Morano, as quoted by Steve Eliot)

At-a-Glance

This myth relies on the use (or in fact misuse) of a particular word – 'saturated'. When someone comes in from a prolonged downpour, they may well exclaim that they are saturated. They cannot imagine being any wetter. That's casual usage, though.

In science, 'saturated' is a strictly-defined term. For example, in a saturated salt solution, no more salt will dissolve, period. But what's that got to do with heat transfer in Earth's atmosphere? Let's take a look.

Heat-trapping by CO2 in the atmosphere happens because it has the ability to absorb and pass on infra-red radiation – it is a 'greenhouse gas'. Infra-red is just one part of the electromagnetic spectrum, divided by physicists into a series of bands. From the low-frequency end of the spectrum upwards, the bands are as follows: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Gamma rays thus have a very high-frequency. They are the highest-energy form of radiation.

As our understanding of the electromagnetic spectrum developed, it was realised that the radiation consists of particles called 'photons', travelling in waves. The term was coined in 1926 by the celebrated physicist Gilbert Lewis (1875-1946). A photon's energy is related to its wavelength. The shorter the wavelength, the higher the energy, so that the very high-energy gamma-rays have the shortest wavelength of the lot.

Sunshine consists mostly of ultraviolet, visible light and infra-red photons. Objects warmed by the sun then re-emit energy photons at infra-red wavelengths. Like other greenhouse gases, CO2 has the ability to absorb infra-red photons. But CO2 is unlike a mop, which has to be wrung out regularly in order for it to continue working. CO2 molecules do not get filled up with infra-red photons. Not only do they emit their own infra-red photons, but also they are constantly colliding with neighbouring molecules in the air. The constant collisions are important. Every time they happen, energy is shared out between the colliding molecules.

Through those emissions and collisions, CO2 molecules constantly warm their surroundings. This goes on all the time and at all levels in the atmosphere. You cannot say, “CO2 is saturated because the surface-emitted IR is rapidly absorbed”, because you need to take into account the whole atmosphere and its constant, ongoing energy-exchange processes. That means taking into account all absorption, all re-emission, all collisions, all heating and cooling and all eventual loss to space, at all levels.

If the amount of radiation lost to space is equal to the amount coming in from the Sun, Earth is said to be in energy balance. But if the strength of the greenhouse effect is increased, the amount of energy escaping falls behind the amount that is incoming. Earth is then said to be in an energy imbalance and the climate heats up. Double the CO2 concentration and you get a few degrees of warming: double it again and you get a few more and on and on it goes. There is no room for complacency here. By the time just one doubling has occurred, the planet would already be unrecognisable. The insulation analogy in the myth is misleading because it over-simplifies what happens in the atmosphere.

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

This myth relies on the use of a word – saturated. When we think of saturated in everyday use, the term 'soggy' comes to mind. This is a good example of a word that has one meaning in common parlance but another very specific one when thinking about atmospheric physics. Other such words come to mind too. Absorb and emit are two good examples relevant to this topic and we’ll discuss how they relate to atmospheric processes below.

First things first. The effect of CO2 in the atmosphere is due to its influence on the transport of 'electromagnetic radiation' (EMR). EMR is energy that is moving as x-rays, ultraviolet (UV) light, visible light, infrared (IR) radiation and so on (fig. 1). Radiation is unusual in the sense that it contains energy but it is also always moving, at the speed of light, so it is also a form of transport. Radiation is also unusual in that it has properties of particles but also travels with the properties of waves, so we talk about its wavelength.

The particles making up radiation are known as photons. Each photon contains a specific amount of energy, and that is related to its wavelength. High energy photons have short wavelengths, and low energy photons have longer wavelengths. In climate, we are interested in two main radiation categories - firstly the visible light plus UV and minor IR that together make up sunshine, and secondly the IR from the earth-atmosphere system.

The Electromagnetic Spectrum

Fig. 1: diagram showing the full electromagnetic spectrum and its properties of the different bands. Image: CC BY-SA 3.0 from Wikimedia.

CO2 has the ability to absorb IR photons – it is a 'greenhouse gas'.So what does “absorb” mean, when talking about radiation? We are all familiar with using a sponge to mop up a water spill. The sponge will only absorb so much and will not absorb any more unless it's wrung out. In everyday language it may be described, without measurements, as 'saturated'. In this household example, 'absorb' basically means 'soak up' and 'saturated' simply means 'full to capacity'. Scientific terms are, in contrast, strictly defined.

Now let's look at the atmosphere. The greenhouse effect works like this: energy arrives from the sun in the form of visible light and ultraviolet radiation. A proportion reaches and warms Earth's surface. Earth then emits the energy in the form of photons of IR radiation.

Greenhouse gases in the atmosphere, such as CO2 molecules, absorb some of this IR radiation, then re-emit it in all directions - including back to Earth's surface. The CO2 molecule does not fill up with IR photons, running out of space for any more. Instead, the CO2 molecule absorbs the energy from the IR photon and the photon ceases to be. The CO2 molecule now contains more energy, but that is transient since the molecule emits its own IR photons. Not only that: it's constantly colliding with other molecules such as N2 and O2 in the surrounding air. In those collisions, that excess energy is shared with them. This energy-sharing causes the nearby air to heat up (fig. 2).

CO2 heat transfer

Fig. 2: The greenhouse effect in action, showing the interactions between molecules. The interactions happen at all levels of the atmosphere and are constantly ongoing. Graphic: jg.

The capacity for CO2 to absorb photons is almost limitless. The CO2 molecule can also receive energy from collisions with other molecules, and it can lose energy by emitting IR radiation. When a photon is emitted, we’re not bringing a photon out of storage - we are bringing energy out of storage and turning it into a photon, travelling away at the speed of light. So CO2 is constantly absorbing IR radiation, constantly emitting IR radiation and constantly sharing energy with the surrounding air molecules. To understand the role of CO2, we need to consider all these forms of energy storage and transport.

So, where does 'saturation' get used in climate change contrarianism? The most common way they try to frame things is to claim that IR emitted from the surface, in the wavelengths where CO2 absorbs, is all absorbed fairly close to the surface. Therefore, the story continues, adding more CO2 can’t make any more difference. This is inaccurate through omission, because either innocently or deliberately, it ignores the rest of the picture, where energy is constantly being exchanged with other molecules by collisions and CO2 is constantly emitting IR radiation. This means that there is always IR radiation being emitted upwards by CO2 at all levels in the atmosphere. It might not have originated from the surface, but IR radiation is still present in the wavelengths that CO2 absorbs and emits. When emitted in the upper atmosphere, it can and will be lost to space.

When you include all the energy transfers related to the CO2 absorption of IR radiation – the transfer to other molecules, the emission, and both the upward and downward energy fluxes at all altitudes - then we find that adding CO2 to our current atmosphere acts to inhibit the transfer of radiative energy throughout that atmosphere and, ultimately, into space. This will lead to additional warming until the amount of energy being lost to space matches what is being received. This is precisely what is happening.

The myth reproduced at the top – incorrectly stating an analogy with roof insulation in that each unit has less of an effect - is misleading. Doubling CO2 from 280 ppm to 560 ppm will cause a few degrees of warming. Doubling again (560 to 1130 ppm) will cause a similar amount of additional warming, and so on. Many doublings later there may be a point where adding more CO2 has little effect, but recent work has cast serious doubt on that (He et al. 2023). But we are a long, long way from reaching that point and in any case we do not want to go anywhere near it! One doubling will be serious enough.

Finally, directly observing the specific, global radiative forcing caused by well-mixed greenhouse gases has - to date - proven elusive. This is because of irregular, uncalibrated or limited areal measurements. But very recently, results have been published regarding the deep reinterrogation of years of data (2003-2021) from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua Satellite (Raghuraman et al. 2023). The work may well have finally cracked the long-standing issue of how to make finely detailed, consistent wavelength-specific measurements of outgoing long-wave radiation from Earth into space. As such, it has opened the way to direct monitoring of the radiative impact (i.e. forcing + feedback) of greenhouse gas concentration changes, thereby complimenting the Keeling Curve - the longstanding dataset of measured CO2 concentrations, down at the planet's surface.

Note: Several people in addition to John Mason were involved with updating this basic level rebuttal, namely Bob LoblawKen Rice and John Garrett (jg).

Last updated on 31 December 2023 by John Mason. View Archives

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Further reading

V. Ramanthan has written a comprehensive article Trace-Gas Greenhouse Effect and Global Warming.

Further viewing

Video by Rosh Salgado on his "All about Climate" YouTube channel in which he debunks Will Happer's claim that the CO2 effect is saturated in the atmosphere:

Comments

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Comments 101 to 125 out of 318:

  1. Tom Curtis @#97 disputes that the heat transport from the surface into the atmosphere is almost a constant whatever the surface temperature. He cites: Increased wind due to increased temperature. Changed Lapse Rate. Change in surface emissivity. Change in conductivity of the air due to higher moisture content. These may all be true [I actually dispute Lapse Rate changes: the lapse rate is controlled by the total energy into the atmosphere - net radiation, condensation of water, conduction, which I claim is virtually constant. So the Lapse Rate is a constant and Lapse Rate feedback may be a furphy.] but the LHS of the equation is always the sunlight absorbed by the Surface. Unless the albedo or solar constant change, sunlight absorbed by the Surface is invariant. On the RHS we have: Surface Energy absorbed into the atmosphere (NET radiation, condensed water vapour, conduction) plus Surface Energy radiated direct to space through the window. This latter term is nearly a constant, particularly if CO2 is nearly saturated (which it seems to be. It might change by a few percent if CO2 doubles - I look forward to calculated values for a doubling of CO2). If CO2 doubles we know that the LHS decreases by approximately 1W/m^2 (increased absorption of sunlight by CO2 in the upper atmosphere). This will approximately balance any decrease in Surface radiation through the window, so the Surface Energy absorbed by the atmosphere will remain the same.
  2. In the headline post (advanced version) the author assumes a "final layer" which is a black body at 220DegK. I have three objections to this: 1. The "Final Layer" is nothing of the sort. Photons are emitted at all levels. Absorption ensures that most never make it out to space through the fog of overlying gas. The average emission height is determined by absorption. In general this level will be different for every frequency. 2. The atmospheric gases are not black bodies - nothing like black bodies. Unlike solids or liquids they do not emit a continuous spectrum, but preferred frequencies (lines), the envelopes of which both in detail abnd as a conglomerate are far from a black body. See http://spectralcalc.com/spectral_browser/db_intensity.php. A black body curve is not appropriate and the "blackbody temperature" cannot be used to estimate the average height of emission. 3. It is implied that the amount of energy absorbed is the difference between two blackbody curves. This is an erroneous view. Energy absorbed into the atmosphere is ALWAYS manifested as kinetic energy (atmospheric heat) at the point of absorption. That energy flows upward by convection and radiation, still manifested as kinetic energy. It is then radiated to Space by the GHGs, primarily Water Vapour, with a little from CO2 (15-18W/m^2) and Ozone. These GHG molecules are energised by collision with other air molecules (around 50 times per nanosecond) and if the energies are right and the star signs are right (ie around one chance in one hundred thousand) a photon is emitted at a preferred frequency. If that photon avoids absorption by other GHG molecules, it escapes to space and that energy is lost from the planet.
  3. novandilcosid @100, in 97 I identified several factors on the RHS of the equation that result in changes in value on the LHS, specifically, in changes to the back radiation. I also identified factors which cause relative changes to the value of the terms on the RHS of the equation. As your argument requires that the LHS determine the value the values on the LHS, but not in turn have their values determined by factors on the RHS, your argument fails because the value of back radiation has been shown to be partially dependent on RHS factors. Further, your argument also depends on the two non-evaporative values on the RHS being constant, and this has also been shown to be false. You chose to ignore that facts I have raised, and simply re-assert your position. Fine - that it your right, but it also make debate with you pointless and uninteresting. I will merely note that keeping your discussion factual seems a low priority to you. Curiously, not only are you uninterested in trying to grapple with the facts I presented, you then go on to refute your own case. First, you indicate that rate of evaporation per degree C is not known, but according to you that value follows by straightforward reasoning from the energy balance equation. Further, you indicate that both constant RHS with a 2.5% increase in evaporation per degree C and a decreasing RHS with a 5% increase in evaporation per degree C are reasonable suppositions. However, both suggest decreases in the value of the non evaporative terms on the RHS, and the second suggests a much larger decrease. These are terms you require to be constant which changing temperature for your argument to succeed, but now you entertain the notion that they are anything but.
  4. Tom Curtis wrote @103 above: "in 97 I identified several factors on the RHS of the equation that result in changes in value on the LHS, specifically, in changes to the back radiation." I think Tom is referring to a different equation to the one I have been using to establish that the Surface Energy absorbed by the atmosphere is nearly a constant, regardless of CO2 concentration or temperature. Naturally this would cause differences of opinion to arise! I have ignored Tom's interesting observations simply because they are not relevant to the case - they amount to identifying variations in terms on the RHS of the equation, and these variations do not affect the hypothesis. The equation I have been using is: Solar_Radiation_Absorbed_into_the_Surface = Surface_Energy_Absorbed _into_the_Atmosphere + Surface _Energy_Radiated_through_the_Window_to_Space The LHS of this equation is only affected by the solar constant, atmospheric absorption of sunlight, and planetary albedo. [It does not contain Back_Radiation, that is within the first term of the RHS.] The LHS is nearly constant. If CO2 is doubled we expect a REDUCTION of about 1W/m^2 due to increased atmospheric absorption of sunlight. On the RHS, if CO2 is doubled, there will be a decrease of Surface Energy escaping to space through the window. How much is unknown by me (it is the subject of this thread, but there does not seem to be a number being cited) but I would expect it is of similar magnitude to the change in the LHS - a DECREASE of about 1W/m^2. IF that is the case then the third term, Surface_Energy_Absorbed _into_the_Atmosphere is a constant. This term contains evaporation, conduction and net radiation, all of which are the varying quantities which Tom has identified. I make no comment on the veracity of his claims at this point, merely restating that this term must be nearly constant. Tom writes: "You chose to ignore that facts I have raised, and simply re-assert your position." I agree. I have ignored his points (this is not to say I don't find them interesting), as I believe them to be irrelevant to the point I have been making. The Surface Energy absorbed by the atmosphere is nearly constant, regardless of surface temperature or atmospheric CO2 content. The degree of saturation is central to this assertion.
  5. Tom Curtis wrote @#103 above: "Further, you indicate that both constant RHS with a 2.5% increase in evaporation per degree C and a decreasing RHS with a 5% increase in evaporation per degree C are reasonable suppositions. However, both suggest decreases in the value of the non evaporative terms on the RHS, and the second suggests a much larger decrease." Tom is correct. The terms within the term "Surface_Energy_Absorbed _into_the_Atmosphere" are Net_Radiation, Evaporation and Conduction. It is known that evaporation INCREASES with temperature. All authorities agree on that. What is not known is by how much. Is it 2.5% (models), 5% (measurement), or 6.5% (Clausius-Clapeyron, assuming constant RH ) per DegC? It is also known that Net_Radiation INCREASES with temperature. But it DECREASES with increased CO2 concentration (back radiation increases slightly as the average altitude from which CO2 earth-bound photons are emitted drops. This level is lower therefore warmer, so there is aqn increase in intensity.)
  6. Tom Curtis also wrote @#103: " it also make debate with you pointless and uninteresting. I will merely note that keeping your discussion factual seems a low priority to you." I expect that Tom would like to withdraw this remark. I hope that my two previous posts have in fact answered his criticisms in detail. If not, perhaps he would be so kind as to point out where not.
  7. novandilcosid @104, I am dropping the debate about the relation between evaporative energy transfers and net radiation. It is too time consuming, and so far as I can tell almost irrelevant to this topic. Indeed the only relevance I can see to global warming is that if your theory were true, the Green House Effect would be stronger than it is currently predicted to be. That is because if the energy flow to the atmosphere were constant with temperature, the energy flow from the atmosphere to space must also be constant with constant insolation regardless of surface temperature. Therefore any adjustment to reduced outgoing radiation due to green house gases must be entirely compensated for by changes in surface temperature, rather than partly compensated for by increased atmospheric temperatures as currently believed. So, unless you can provide a clear and succinct statement of your thesis and it relevance, I will consider it of topic and not worth the energy.
    Response: [DB] Fixed closing bold tag.
  8. novandilcosid @99 asks, ""[H]ow much additional surface energy is absorbed outside the saturated 625-725 band, ie by how much does the window close, in W/m^2? The following chart from SOD shows the change in net forcing from a doubling of CO2: The total forcing for such a doubling is, of course, 3.7 W/m^2, with the vast majority of that being in the wings. You will notice that this is the forcing at 200mb, ie the tropopause (as also for the graphs of transmitance and change in transmitance at @86 and 82 respectively. novan will of course point to the influence of the stratosphere, but that is greatly exaggerated by him, and for two reasons. First, to a reasonable approximation the energy in the stratosphere comes from UV radiation absorbed by ozone. Increasing the CO2 concentration does not increase that energy. Rather, it cools the stratosphere by radiating away that energy more efficiently. The result is a slight increase of radiation in the primary band of CO2 emissivity, but a reduction in the IR radiation by ozone (the other main gas that radiates energy away from the stratosphere). The result in zero net change in the OLR. The second effect relates to the exchange of IR energy between the top of the troposphere and the stratosphere. Increased CO2 concentration reduces IR radiation from the troposphere to the stratosphere, further cooling the stratosphere (although how strong this effect is a matter of debate). But the increased proportion of stratospheric energy radiated by CO2 means there is an increase in energy radiated from the stratosphere to the troposphere by CO2. This, however is again balanced by a reduction in the IR radiation emitted by ozone to the surface. In Line by Line and energy balance models, these effects are taken into account in determining the forcing at the tropopause. Radiative forcing is, after all, "The radiative forcing of the surface-troposphere system due to the perturbation in or the introduction of an agent (say, a change in greenhouse gas concentrations) is the change in net (down minus up) irradiance (solar plus long-wave; in Wm-2) at the tropopause AFTER allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values." Consequently the above graph of change in radiative forcing at 200 mb includes the effects of the changes in the stratosphere. Of course, novan may well dispute this, so the best thing to do is to got to empirical data. Novan's thesis is that the net effect of adding CO2 to the atmosphere is to increase radiation to space from CO2, thus cooling the Earth. (See 81 and 89 above). The following are graphs of the change in IR radiation (measured as brightness temperatures) between 1970 and 1997. Figure b top shows the change in the tropical Pacific (between 10 degrees north and 10 degrees south); while figure b bottom shows the "near global" changes (between 60 north and 60 south). The middle shows the tropical case as predicted by a model. The first think to notice is that in the CO2 emission wavelengths, the emissions are either reduced or barely increased in the tropical observations; and that for the "near global" observations and the simulation they are reduced. The second thing to notice is that the net radiation to space has increased in the tropical case (and possibly also, but slightly, in the "near global" case. This indicates an overall increase in temperature of the Earth/atmosphere system in 1997 relative to 1970 which is anomalously large compared to that expected by the GHE alone. The obvious reason for this is the 1997/1998 El Nino which commenced in April of 1997 (the data is for the April-June period). The obvious thing to do is to remove the temperature effects from the record. Doing so reveals graph C in the figure (and figure 1 in the article above) which shows a clear reduction radiation in the CO2 band. Thus novan's thesis is clearly refuted by the observational data.
  9. Tom Curtis responded at 107 to my very clear post at #104 in which I said: "Solar_Radiation_Absorbed_into_the_Surface = Surface_Energy_Absorbed _into_the_Atmosphere + Surface _Energy_Radiated_through_the_Window_to_Space The LHS of this equation is only affected by the solar constant, atmospheric absorption of sunlight, and planetary albedo. [It does not contain Back_Radiation, that is within the first term of the RHS.] The LHS is nearly constant. If CO2 is doubled we expect a REDUCTION of about 1W/m^2 due to increased atmospheric absorption of sunlight. On the RHS, if CO2 is doubled, there will be a decrease of Surface Energy escaping to space through the window. How much is unknown by me (it is the subject of this thread, but there does not seem to be a number being cited) but I would expect it is of similar magnitude to the change in the LHS - a DECREASE of about 1W/m^2. IF that is the case then the third term, Surface_Energy_Absorbed _into_the_Atmosphere is a constant. This term contains evaporation, conduction and net radiation, all of which are the varying quantities which Tom has identified. I make no comment on the veracity of his claims at this point, merely restating that this term must be nearly constant." Tom said: "unless you can provide a clear and succinct statement of your thesis and it relevance, I will consider it of topic and not worth the energy." I am somewhat at a loss as to how to proceed. My post is very clear, and no error has as yet been demonstrated, Tom's previous efforts having been irrelevant to the discussion as they did not address the clear statements made. For the record: 1. All the solar energy absorbed into the surface must be exported from the surface. 2. There are only two places that energy can go, either into the atmosphere or out into space. 3. The solar input is nearly constant (there is a small reduction if CO2 is increased) and we expect a small reduction in the export to space (the window slightly tightens). 4. That means that the export of energy from the surface into the atmosphere is nearly constant regardless of temperatures and CO2 concentrations There are a couple of things to note: 5. The above assumes integration over the whole surface for one year then averaging. It also assumes a planet in equilibrium with Space. 6. A constant energy flow from the surface into the atmosphere means a constant lapse rate. The lapse rate does not change with more evaporation, because any increase in evaporation is offset by decreases in energy flows from net radiation/conduction. 7. It is untrue to say that increasing CO2 increases the amount of surface energy trapped by the atmosphere. That energy entrapment is essentially constant.
    Response: (DB) Except that the energy balance at the TOA is not balanced; thefore the planet is not in equilibria in its energy budget. Your argument therefore fails this initial test.
  10. Tom Curtis posted at #108: "novandilcosid @99 asks, ""[H]ow much additional surface energy is absorbed outside the saturated 625-725 band, ie by how much does the window close, in W/m^2?" The following chart from SOD shows the change in net forcing from a doubling of CO2... I note in passing that increased Radiative Forcing (=energy inbalance at the Tropopause) is entirely different to increased absorption of Surface Energy, so that Tom's entire post is a confusing non-response to the question. Does anyone have a figure for the decrease in Surface Energy passing through the window due to a doubling of CO2 and assuming no temperature change at the surface?
    Response: (DB) Your final assumption is flawed so your question is meaningless.
  11. Tom Curtis posted at #108: "The result in zero net change in the OLR." Working again on the model of a planet where energy flows are integrated over the surface for a year, then averaged, and assuming the planet is in energy equilibrium with Space, we can write: Sunlight hittng the planet = reflections + sunlight absorbed then reradiated. or, put another way, Sunlight hitting the planet = Outgoing Shortwave Radiation (=reflections) + Outgoing Long Wave Radiation (sunlight absorbed and reradiated) It is clear from this that OLR varies only if the Earth's albedo changes. It is sometimes claimed that the warming effect of GHGs must mean OLR is increasing or perhaps decreasing. But not in an equilibrium planet with no change in cloud or ice cover.
  12. DB reponded to my post at #109 with "Except that the energy balance at the TOA is not balanced; thefore the planet is not in equilibria in its energy budget. Your argument therefore fails this initial test." He is sort of correct: on short timescales and at particular locations, the planet is not in equilibrium with Space. The energy balance changes from positive to negative all the time. But INTEGRATED on long timescales that balance has to be stable. Otherwise the planet will change to make it so. For example over the last 10 years the planetary average temperature has not changed. So the integration of energy input/output will be balanced or nearly so. That's what the Kiehl & Trenberth diagram used by the IPCC in 2007 says. (or are we saying that the IPCC was wrong to use that diagram?) I fail to see therefore why my innocous observation that there is no change in surface energy into the atmosphere is invalidated.
    Response:

    [DB]

    "But INTEGRATED on long timescales that balance has to be stable. Otherwise the planet will change to make it so." 

    On very long timescales, it is in balance.  Right now, due to the forcing from CO2, it is not.  So the planet is seeking to regain that balance by raising the tropospheric temperatures as well as sequestering heat/energy into the oceans.  This is very basic, PRATT stuff.

    "For example over the last 10 years the planetary average temperature has not changed."

    Incorrect.  This fails on multiple levels:

    1. The global temperature record shows the most recent 10 year period as the hottest in the instrumental record.
    2. Selecting a short 10 year period is cherry-picking, as that period is typically too short to carry statistical significance.  However, allowing for exogenous factors, the planet has shown statistically significant warming since 2000.

    I fail to see, therefore, why you cannot see your position is invalidated from the initial premise.

  13. novandilcosid @110, your post to which I responded asked both about the change in transmittance (aborption of surface radiation), and the change in atmospheric emissions at the top of the atmosphere. This first was shown clearly in post 82. The combined effect was clearly shown in my first figure @108. You dismiss that because that highly relevant data was not in the exact format your required to impose your spin. You at the same time simply ignore the impirical data that refutes your thesis. Well, your game is now very clear, and it is not honest inquiry. If you ever want to try that, run a full Line By Line calculation of the emissions spectrum (as has been done by the people whose results you simply dismiss), and then if you come up with an interesting result, try again. In the mean time, I am not interested in pretending the partial calculation of a result on the back of an envelope can in any way refute the full calculation of the result with computers using a variety of methods, all coming up with essentially the same result.
  14. In response to my question "Does anyone have a figure for the decrease in Surface Energy passing through the window due to a doubling of CO2 and assuming no temperature change at the surface?" DB wrote: " Your final assumption is flawed so your question is meaningless" The whole of this thread is about how much the window closes (note: not about the export to space but about the absorption of radiation). I'll ask the question a different way: "What is the percentage change in the proportion of surface radiation absorbed by CO2 for a doubling of CO2?"
    Response:

    [DB] As the OP shows, the whole of this thread is about:

    "If the CO2 effect was saturated, adding more CO2 should add no additional greenhouse effect. However, satellite and surface measurements observe an enhanced greenhouse effect at the wavelengths that CO2 absorb energy. This is empirical proof that the CO2 effect is not saturated."

  15. novandilcosid at 15:19 PM on 25 April, 2011 David Archer (Univ. Chicago) made available online an older version of Modtran. I'm not sure how accurate it is, but you may find it a helpful tool to play around with that kind of hypothesis.
  16. novandilcosid, I note again that you are not really arguing that the CO2 greenhouse effect is saturated... you are arguing that it does not exist at all. Yet you have refused to respond to the obvious questions that raises: 1: Why do Spencer, Christy, Pielke 1&2, and every other 'skeptic' scientist (not to mention all mainstream scientists and all physics texts on the subject) claim that CO2 DOES cause the planet to be significantly warmer than it would be without? 2: If CO2 and other atmospheric gases can only slightly decrease the amount of radiation reaching the surface and thus cause slight cooling as you claim, then why is the Earth more than 30 C warmer than could be explained by sunlight hitting an airless rock at this distance from the Sun? You stand at odds with nearly two centuries of scientific understanding. How do you explain that? You argue that energy in must equal energy out (though this isn't true when a system is not in balance), but ignore the fact that this says nothing about the actually relevant issue of energy within the system. Consider a house (or planet Earth) which is receiving a fairly constant influx of energy from a furnace (or the Sun). Once equilibrium is reached the energy leaving must be equal to the energy entering... but the amount of energy within the system can be very different depending on how much insulation (or greenhouse gases) it has. One constant energy source... constant energy emission from the system... but DIFFERENT amounts of energy within the system and therefor different temperatures. Ergo all your arguments about energy in and energy out are irrelevant. The question at hand is energy within the system.
  17. novandilcosid (RE: 110), "I note in passing that increased Radiative Forcing (=energy inbalance at the Tropopause) is entirely different to increased absorption of Surface Energy, so that Tom's entire post is a confusing non-response to the question. Does anyone have a figure for the decrease in Surface Energy passing through the window due to a doubling of CO2 and assuming no temperature change at the surface?" The figure is 3.7 W/m^2. When CO2 is doubled, the window (i.e. transmittance) reduces by 3.7 W/m^2 and the atmosphere absorbs an additional 3.7 W/m^2 of surface emitted radiation, half of which goes down to the surface and half of which goes up out to space (1.85 W/m^2 up and down). It has been claimed here and elsewhere that the halving effect is already accounted for in the 3.7 W/m^2 figure; however, I have not been able to verify this through numerous inquiries to the climate science community. No one can give me a straight answer, but I'm still working on it.
    Response: (DB) In reality, you were given an answer, which you have chosen to ignore.
  18. novandilcosid (RE: 110), If the net effect at the surface is 3.7 W/m^2, then the "window" should close by 7.4 W/m^2 when CO2 is doubled.
  19. I should say the "window" should decrease by 7.4 W/m^2 when CO2 is doubled (not close). Trenberth et al 2009 has the window being 70 W/m^2 with the atmosphere emitting 157 W/m^2 down and 169 W/m^2 up (48% down and 52% up), if your interested in running some numbers.
  20. RW1 - Your erroneous "halving" has been addressed repeatedly, you have simply chosen to disregard the answers you have received. 3.7 W/m^2 is the drop in IR emitted to space for a doubling of CO2. This is due both to the rise in tropopause and effective emission altitude from increased CO2 concentration (and hence lower CO2 emitting temperature) and absorption band expansion. The window decreases slightly, but the predominant change is decreased emissions across the CO2 absorption bands. Hence "If the net effect at the surface is 3.7 W/m^2, then the "window" should close by 7.4 W/m^2 when CO2 is doubled" is simply wrong. There are two effects, not one, and your insistence on assigning all change to one effect has been corrected over and over again. Anyone interested in that discussion should look at the Lindzen and Choi thread, where RW1 and others were informed of the details over 448 postings. Please do not rehash that here. This thread is about CO2 saturation, and it is hence off-topic.
  21. Re: my past post - CO2 effects are on topic. However, George White/co2isnotevil's incorrect assumptions about 'halving' really are not. 3.7 W/m^2 is the decrease in IR leaving the atmosphere for a CO2 doubling, as per line-by-line multi-level atmospheric modeling, CO2 spectra and physics, and confirmed by top of atmosphere satellite measurements. No 'halving' occurs.
  22. RE: DB and KR, I haven't ignored or disregarded anything. Just because I was given an answer doesn't mean it is the correct answer. I'm still working on the issue and hope to eventually resolve it once and for all.
  23. KR (RE: 121), You even stated the following here: "As has been said here, repeatedly, the 3.7 TOA number means that 7.4 W/m^2 is being absorbed and radiated isotropically from CO2." There is definitely a halving effect. The fundamental question is if the 3.7 W/m^2 represents the post or pre halving effect. If it represents the post halving effect, as claimed here, then the "window" or transmittance (i.e. the amount of surface emitted that passes straight through the atmosphere unabsorbed and goes out to space) should reduce by 7.4 W/m^2.
  24. novandilcosid, I don't want to rehash this debate here. See the posts by 'co2isnotevil' and myself in the following threads: Here and Here Also, this paper by co2isnotevil: "Proof that only half of absorption affects the surface"
  25. RW1 - As has been said to you before, the windowing effect (where IR goes straight from the surface to space) is only part of the reduction in IR. The rest occurs in the full absorption bands (where IR from the surface makes it only 10's or 100's of meters before absorption), as increased CO2 concentrations raise the level of effective tropospheric radiation to colder altitudes. Why are you disregarding that very significant effect? Why are you claiming that all of the IR decrease occurs by a reduction of the 40 W/m^2 window, when that is clearly not the case?

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