Sunday, November 20, 2011

Physical analysis shows CO2 is a coolant for the atmosphere

There is a fallacy dominating the way of our thinking in current climate research that radiative gases such as carbon dioxide and water vapour are regarded greenhouse gases that trap heat and warm up the atmosphere.  Physics analysis of carbon dioxide, oxygen and nitrogen molecules, however, tells a different story: carbon dioxide is cooler than, gains heat by molecular collision from, and dissipates heat by radiation for nitrogen and oxygen.  Indeed, CO2 is a coolant of the atmosphere, and it is nitrogen and oxygen gases that award the Earth a warm liveable near surface atmosphere. 

The physical principle behind the analysis lies in the Kirchhoff’s law of 19th century radiation physics, which can be restated in plain English as: an object that absorbs emits and an object that emits absorbs.   Absorption and emission are two inseparable equivalent identities of the same physical essence.  Carbon dioxide absorbs infrared therefore it emits as well thermal radiation.  Nitrogen and oxygen do not absorb, therefore do not emit.  CO2 approaches 0 K because of its emission if there is no radiation source; absorption of the thermal radiation from the earth ground surface rises CO2 temperature from -273.15°C to -78°C only.  CO2 gains heat by colliding with warmer nitrogen and oxygen to rise its temperature further, which can be measured by spectroscopy.   

We will have a better understanding of the physical principle if one notices that a computer case is often designed black.  This is because a black surface emits more heat out so the computer will be cooler.  On the other hand, an industrial boiler is usually painted silver to reduce thermal emission to reserve heat. 

With this alternative interpretation, we have a better explanation of the temperature-altitude profile of the atmosphere; in particular, a better explanation of the existence of the thermosphere where the molecular temperature of residual oxygen gas is well above 100°C ¾ CO2 gas is sorted out in the thermosphere due to its heavier molecular weight. 

A PDF file of the full manuscript entitled “Role of heat reservation of N2 and O2 and the role of heat dissipation of CO2 and water vapour” is available to download if interested.

(By Dr. J. Cao, Australia)


  1. Dear Dr. Jinan Cao,

    Your new blog was drawn to my attention by a fellow skeptic of the greenhouse gas theory (GHE). As such, I write to you as the international coordinator of the ‘Slayers’ think tank best known for our book, ‘Slaying the Sky Dragon: Death of the Greenhouse Gas Theory.’

    From viewing your site it appears that you share our views and are seeking to persuade fellow scientists and the general public that the GHE is bogus. We would like to read your manuscript entitled ‘Role of heat reservation of N2 and O2 and the role of heat dissipation of CO2 and water vapour’ but are unable to download the PDF.

    We are two-dozen specialists working in science, engineering, math, law and publishing dedicated to debunking the GHE via our articles, books, websites and public speaking and broadcasting.

    We are gaining traction with our science and are looking to expand by recruiting additional experts to our team. Among our projects is the new ethical science association, Principia Scientific International (PSI) that we intend to develop as a publishing hub untainted by the corruption that now dogs science journalism and the established peer-review system.

    I understand that your fine Physical Science credentials include your work as Australian Councillor for the International Confederation for Thermal Analysis & Calorimetry and membership of the International Advisory Board for the first Beijing International Huaxia Conference on Thermal Analysis & Calorimetry.

    My colleagues and I would be most interested to discuss with you the possibility of working together in some mutually beneficial way to further our shared objectives on this issue.

    If the idea appeals to you please get back to me when your priorities allow.

    Yours truly,

    John O’Sullivan LLB, BA(Hon), PGCE
    Project Coordinator
    Principia Scientific International & ‘The Slayers’

  2. This is in line with an experiment which can be viewed at the site below entitled "MUST SEE YOUTUBE: William R. Pratt. AGW Debunked for £5.00"

  3. Interesting concept! I would like to know more. Where can I download a copy of the pdf from.

  4. This is a absolutely fundamental question if carbon dioxide causing global warming as climate alarmists claimed or cooling agent as you pointed out here.

    Why don't scientists answer this question first before going to waste huge amounts of money to carry on carbon dioxide sequestration etc?

    I appreciate your courage and dedication to answering this question with strong scientific evidence from your expertise area. Please keep on chasing the truth as a real scientist to be responsible to the society and progressing of civilization to avoid unnecessary financial hardship to the world.

  5. Reply to Fred Furkenburger:
    Sorry for the delay. The PDF file can be downloaded by following the link:

  6. Hello Dr cao

    Thank you very very much for the manuscript pdf. I plan on reading it a couple of more times (I'm not the sharpest tool in the shed).

    May I ask from where the temperature of CO2 of -78C comes from?
    Not having the knowledge base, I'm having trouble understanding how radiation from the ground surface raises CO2 T by 195DegC



  7. ooops, my apologies Dr Cao.
    I see the answer to my question is on page 4 of your pdf


  8. This comment has been removed by the author.

  9. Excellent paper, Jinan. It must be right, as it disagrees 180° with the AGW-GHG speculation.

    But pleeeeaazzze get a native-English-speaking co-author or editor. Some of your vocabulary and grammar and syntax is very off-putting and distracting and confusing. If necessary, you could even use someone who speaks Strine.

  10. Hello again Dr Cao

    May I impose on you to let me know if I've understood your pdf to a sufficient level. I summarise it thus...

    For the absorption bands 13.04um-17.64um, the radiative equilibrium temperature of CO2 is -77.8DegC

    However, according to the spectral lines in Fig1, the temperature of CO2 is -56.65DegC.
    The difference is explained by molecular collisions between CO2 and N2/O2.

    The above can be further explained by your thought experiment.
    When CO2 is exposed to low sources of radiation (such as that from earths surface at 12DegC) CO2 is a nett cooling agent.
    When CO2 is exposed to high sources of energy (i.e. 145DegC or above) it becomes a nett warming agent.

    Do I have the above correct?

    The further question I would ask is, would you consider the Suns IR radiation as a high source of energy? (I note Wiens law, at ALL WAVELENGTHS, a hotter object emits MORE than a cooler object)
    If so, would this make CO2 a warming agent during the day, and a cooling agent during the night?


  11. To Oguzhan Brisbane;

    Thanks for your comments. Your understanding is correct.

    Though the Sun emits more radiation than the Earth, irradiance over the CO2 absorption bands is much less. Sometoimes we say short wave and long wave radiations. Thus, even during the day, the thing does not change too much.
    Regards J. Cao

  12. "... Kirchhoff’s law ...: an object that absorbs emits and an object that emits absorbs. ... Carbon dioxide absorbs infrared therefore it emits as well thermal radiation."

    Not exactly. Kirchoff's Laws apply to "bodies" - solids and liquids; not low temperature gases. Isolated gas molecules are excited and relaxed at the same rate because of the inherent equality of the rates of stimulated absorption and emission. [It's the low probability of spontaneous emission that makes lasers possible. In fact, the first laser was a CO2 gas laser.]

    When CO2 molecules absorb IR radiation they just get warmer, increase their rms speeds, and rise by expansion; pressure drops and cooling results from adiabatic expansion; and they also lose KE by collisions with N2, O2, and H2O.


  13. To Ron;
    The Kirchhoff's law of course applies to gas as well, no matter what temperature it is. If not, one should be able to invent "perpetual motion machines."

    The statement in the blog refers carbon dioxide emits e*Sigma*T^1/4 24/7, a different subject from what you said about molecular excitation and relaxation equilibrium (there are various solid lasers as well). Sigma is a constant, so CO2 will keep emitting until its temperature reaches 0 K if there is no radiation source for absorption. This is because CO2 absorbs, so a<>0, then the Kirchhoff's law says e<>0 for CO2.

    It is widely perceived as CO2 is in the same temperature as N2O2; absorption makes it warmer, it then passes the energy to N2O2 by molecular collisions. Actually, CO2 will be in absolute 0 K if no absorption of the radiation from the earth ground surface, and if it does not gain heat from N2O2. Absorption of the radiation from the earth ground surface warms it up to -78C (lowest altitude. At 20 km high altitude, around -100C ~ -120C). CO2 gains heat from N2O2 to reach its actual temperature (-56C, also altitude dependant) that are measured by spectroscopy.

    J. Cao

  14. An interesting assessment of CO2 from 1st principles. Have you done similar calculations for other GHGs (like water vapor)? It would be interesting to know which ones warm and which ones cool.

    1. To Anonymous Dec 30, 2011
      Thank you very much for your comment. The article "Role of heat reservation of n2 and o2 and the role of heat dissipation of water vapour and co2" basically tries to reverse a wide spread misconception that confuses two different things: "absorption leads to warming" and "absorbing object is warmer than non-absorbing ones". Thre formaer is always correct, and the latter is only true where there is intense radiation source. In the domain where there is no or only week radiation source, absorbing objects are cooler than non-absorbing objects.

      The article gives a quantitative calculation for co2 but only a qualitative description for water vapour. This is because the absorption bands for water vapour are more complex than that for co2. Only when these bands are fully formulised mathematically, a quantitative discussion can be further conducted.

  15. I agree, but I am not sure about the significance of the CO2 cooling effect (climatically). My explanation is that the atmosphere is pre-dominantly warmed by non-radiative modes and cooled exclusively by radiation. Therefore, in average, N2/O2 (the bulk) warm the CO2, which radiates and cools.


    1. The significance of "greenhouse gases" (inc. CO2) cooling can be accessed by the lapse rate in the tropesphere and the temperature of tropepause etc.

  16. Sigh,

    The PDF is no longer available, it seems.