Earth and Mars: Evolution of Atmospheres and Surface Temperatures
@article{Sagan1972EarthAM, title={Earth and Mars: Evolution of Atmospheres and Surface Temperatures}, author={Carl E. Sagan and George Mullen}, journal={Science}, year={1972}, volume={177}, pages={52 - 56} }
Solar evolution implies, for contemporary albedos and atmospheric composition, global mean temperatures below the freezing point of seawater less than 2.3 aeons ago, contrary to geologic and paleontological evidence. Ammonia mixing ratios of the order of a few parts per million in the middle Precambrian atmosphere resolve this and other problems. Possible temperature evolutionary tracks for Earth and Mars are described. A runaway greenhouse efect will occur on Earth about 4.5 aeons from now…
755 Citations
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Professor Cook deals with some of these problems in this article, which is a summary of the inaugural lecture he gave as professor of geophysics at Edinburgh on January 15.