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Science 21 December 2007:
Vol. 318. no. 5858, pp. 1903 - 1907
DOI: 10.1126/science.1147039
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Reports

A Sulfur Dioxide Climate Feedback on Early Mars

Itay Halevy,1* Maria T. Zuber,2 Daniel P. Schrag1

Ancient Mars had liquid water on its surface and a CO2-rich atmosphere. Despite the implication that massive carbonate deposits should have formed, these have not been detected. On the basis of fundamental chemical and physical principles, we propose that climatic conditions enabling the existence of liquid water were maintained by appreciable atmospheric concentrations of volcanically degassed SO2 and H2S. The geochemistry resulting from equilibration of this atmosphere with the hydrological cycle is shown to inhibit the formation of carbonates. We propose an early martian climate feedback involving SO2, much like that maintained by CO2 on Earth.

1 Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA.
2 Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

* To whom correspondence should be addressed. E-mail: ihalevy{at}fas.harvard.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Orbital Identification of Carbonate-Bearing Rocks on Mars.
B. L. Ehlmann, J. F. Mustard, S. L. Murchie, F. Poulet, J. L. Bishop, A. J. Brown, W. M. Calvin, R. N. Clark, D. J. D. Marais, R. E. Milliken, et al. (2008)
Science 322, 1828-1832
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Science. ISSN 0036-8075 (print), 1095-9203 (online)