Comparative analysis of the atmospheres of early earth and early Mars
Assuming that the primitive atmospheres of Mars and earth were similar and that present differences in atmospheres of earth and Mars are a result of their different distances from the sun and their different masses, the atmospheres of the early earth and early Mars were analyzed. A one-dimensional radiative-convective model derived from that of Kasting et al. (1984) and Kasting and Ackerman (1986) was then used to determine if a 1.3-bar CO2 partial pressure on Mars (which is equivalent to about 9 bars on earth) is consistent with the climatic conditions thought to have existed on earth four billion years ago. Results indicate that a dense CO2 atmosphere on early Mars at perihelion is consistent with conditions expected to have existed four billion years ago on earth. Earth would then have had a stable atmosphere with temperatures warm enough to support liquid water on the surface.