The presence of water on ancient Mars is a paradox. There’s plenty of geographical evidence that rivers periodically flowed across the planet’s surface yet Mars should have been too cold to support liquid water at that time. Now, researchers suggest that early Mars may have been warmed intermittently by a powerful greenhouse effect. They found interactions between methane, carbon dioxide and hydrogen in the early Martian atmosphere may have created warm periods when the planet could support liquid water on the surface.
(via WSJ)
