Doubling the CO2 cools or heats?

Giora Shaviv*, Nir J. Shaviv, Rainer Wehrse

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


We calculate the effect that CO2 enhancement has on the radiative transfer in the Earth atmosphere. To this goal, we apply a recent algorithm developed by Wehrse and Shaviv. The calculation differs from previous calculations in that it includes several million molecular lines and in that it iterates for the temperature profile, so as to satisfy radiative equilibrium. The main result we find is that the effective optical depth of the CO2 band at 14,000-16,000Å is of the order of unity, and that by increasing the amount of CO2, the optical depth increases primarily at high altitudes. With it, the absorption of solar energy increases at high altitudes but it decreases at low altitudes above the planetary boundary layer. As a consequence, the temperature rises at altitudes of about 20km, it decreases at low altitudes, but the surface actually warms. Note that the calculation does not include yet the effects of convection, nor does it include indirect effects on the T such as through water vapor or cloud feedbacks.

Original languageAmerican English
Pages (from-to)494-501
Number of pages8
JournalMemorie della Societa Astronomica Italiana, Supplementi - Journal of the Italian Astronomical Society, Supplement
Issue number1
StatePublished - 2010
Event8th International Workshop on Multifrequency Behaviour of High Energy Cosmic Sources - Vulcano, Sicily, Italy
Duration: 25 May 200930 May 2009

Bibliographical note

Publisher Copyright:
© SAIt 2010.


  • CO
  • Molecular absorption
  • Planetary atmosphere
  • Planets
  • Radiative transfer


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