Mars Climate, Now and In the Past
Mars' Unusual Climate
The unusual climate of Mars makes it not quite right for life as we know it on Earth. If the climate were warm enough, water would not freeze into the ground but vaporize into the atmosphere. Lots of water vapor in the atmosphere would help keep Mars warm, and prevent water from freezing.
It seems that at one time, though, water was on the surface of Mars. One might think then that the ancient river channels might be the remains of a time
when water ran on the surface of Mars like it does on Earth, but that might
not be so.