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CO_2 Greenhouse in the Early Martian Atmosphere: SO_2 Inhibits Condensation

Yung, Y. L. and Nair, H. and Gerstell, M. F. (1997) CO_2 Greenhouse in the Early Martian Atmosphere: SO_2 Inhibits Condensation. Icarus, 130 (1). pp. 222-224. ISSN 0019-1035. doi:10.1006/icar.1997.5808.

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Many investigators of the early martian climate have suggested that a dense carbon dioxide atmosphere was present and warmed the surface above the melting point of water (J. B. Pollack, J. F. Kasting, S. M. Richardson, and K. Poliakoff 1987.Icarus71,203–224). However, J. F. Kasting (1991.Icarus94,1–13) pointed out that previous thermal models of the primitive martian atmosphere had not considered the condensation of CO_2. When this effect was incorporated, Kasting found that CO_2 by itself is inadequate to warm the surface. SO_2 absorbs strongly in the near UV region of the solar spectrum. While a small amount of SO_2 may have a negligible effect by itself on the surface temperature, it may have significantly warmed the middle atmosphere of early Mars, much as ozone warms the terrestrial stratosphere today. If this region is kept warm enough to inhibit the condensation of CO_2, then CO_2 remains a viable greenhouse gas. Our preliminary radiative modeling shows that the addition of 0.1 ppmv of SO_2 in a 2 bar CO_2 atmosphere raises the temperature of the middle atmosphere by approximately 10 degrees, so that the upper atmosphere in a 1D model remains above the condensation temperature of CO_2. In addition, this amount of SO_2 in the atmosphere provides an effective UV shield for a hypothetical biosphere on the martian surface.

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Yung, Y. L.0000-0002-4263-2562
Alternate Title:CO2 Greenhouse in the Early Martian Atmosphere: SO2 Inhibits Condensation
Additional Information:© 1997 by Academic Press. Received September 19, 1996; revised June 23, 1997. We thank Dave Crisp and Yibo Jiang for valuable inputs to the paper, and Larry Trafton and an anonymous reviewer for useful comments. This work was supported by NASA Grant NAGW-4849 to the California Institute of Technology. Contribution number 5751 from the Division of Geological and Planetary Sciences, California Institute of Technology.
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
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Subject Keywords:Mars; climate; atmosphere; evolution; greenhouse
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Caltech Division of Geological and Planetary Sciences5751
Issue or Number:1
Record Number:CaltechAUTHORS:20140819-113543746
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Official Citation:Y.L. Yung, H. Nair, M.F. Gerstell, CO2 Greenhouse in the Early Martian Atmosphere: SO2 Inhibits Condensation, Icarus, Volume 130, Issue 1, November 1997, Pages 222-224, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48684
Deposited By: Ruth Sustaita
Deposited On:19 Aug 2014 20:29
Last Modified:10 Nov 2021 18:34

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