A collection of posts regarding the CO2 greenhouse effect and AGW

  1. The atmosphere
  2. Radiative Forcing of CO2
  3. The CO2 GHE demystified
  4. A simple model of the CO2 greenhouse effect
  5. Updated CO2 Greenhouse Model
  6. Why CO2 is not the cause of “Hothouse Venus”
  7. Logarithmic dependence of temperature on CO2 levels
  8. CO2 greenhouse effects
  9. Doubling CO2 and basic physics
  10. Radiative Equilibrium & Convection
  11. Effective Emission Height
  12. Mars Greenhouse effect
  13. Thermal inertia and climate feedbacks
  14. Tracking down climate feedbacks
  15. Carbon Magic

8 Responses to CO2 GHE

  1. jerry stockton says:

    I was reading your February 2011 post on CO2 doubling. As a person who has worked with CO2 lasers for years I am confused by almost all of the analysis I read. As you point out, CO2 absorbs most of its energy in the 15 micron band. My experience tells me that it reradiates the energy between 9 and 10 microns which is in the middle of the earths transparent “zone” That would tend to make me believe that the reradiated energy would remove itself rather than warm. Where am i wrong here.

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  4. Yeah that seems about right.

    What if we can start clawing greenhouse gases back?


  5. Hammad says:

    Hello dear hope you are fine i want to know life of atmospheric carbon dioxide.Answer or share some literature related life of atmospheric carbon dioxide

  6. Rodney M says:


    I’ve been doing some independent analysis of the greenhouse effect for some time and enjoy your blog as a source of useful information. I’ve accumulated a few questions during that time which I haven’t been able to find answers to yet. I’ve got a BSc in physics and a MASc in EE (device physics focus), but both are ancient. I look to you and your followers for any insight you can share. I think I’m placing my first questions in the best location on your blog. Thanks to you and others in advance if you have some wisdom and possibly references to share.

    My first questions are around CO2 as a GHG – I’m selecting that GHG since it is likely the most studied, but the answers would likely apply to others such CH4 and N2O. For the sake of clarity, the question is climate change related and not high-energy physics related so I’m focused on T <300K and P < 1 atm. This may "freeze out" certain effects above such levels found in non-climate change physics that I want to ignore as I want to keep the physics related to Earth's atmosphere only.

    Preamble to questions: In the region of 15um where there is a strong absorption band, we understand that most of the infrared emission from Earth in that region is absorbed within the first few meters above the ground. The relaxation time of the remission of an absorbed photon by a CO2 molecule is relatively short and creates a ro-vibrational frequency that is similar. I've never come across anything so far talking about multiple photons being absorbed by a single CO2 molecule before a reemission such that there is the possibility of a released photon at approximately twice the energy being released if two state levels are dropped in the relaxation.

    Question 1: For T & P at or below levels above, will CO2 molecules typically only achieve a first energy absorption state (one photon) vibrational mode before sometime later emitting the photon?

    Question 2: If yes, are additional photons frozen out of being absorbed while the CO2 molecule is in an excited state, and if not, what would the distribution be for multiple photons absorbed by the same CO2 molecule before a photon is released?

    Question 3: If question 2 is yes, what is the physics reason for the "freeze out" that limits the vibration to only a single photon's energy at a time?

    Question 4: If question 2 is yes, it would seem to me that additional photons would bypass those excited molecules no matter the alignment and then get absorbed further away by molecules that align and are in a resting state. Does that seem reasonable?

    • Clive Best says:

      A quick answer.

      The way to think about it IMHO is that radiation from the sun heats the surface ( modulated by clouds). The surface then cools by IR radiation (Stefan Boltzman). S-B frequencies coinciding with CO2 and H2O resonant Frequencies are absorbed by greenhouse gases and re-emited up through the atmosphere to where the atmosphere is thin enough for those photons to escape to space. As a result the surface loses heat faster through convection of warm surface air upwards to a height where the air is thin enough for all radiation to escape to space. This defines the tropopause where convection stops. Sorry this is a bit short but it is late here in UK!

  7. Dr Clive Best says:

    The only thing that matters is the temperature of CO2 molecules when they radiate to space. The temperature mostly follows the moist lapse rate caused by convection of heat from the surface. The IR spectra observed from space shows how CO2 wavelengths are from higher (colder) heights, likewise methane, and H20. Energy balance with the solar radiation is achieved at the effective emission height. The lapse rate ensures that the surface keeps warm for life to flourish.

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