Re: Would a terraformed atmosphere on Mars be able to hold a stabke temp?

Actually, it is possible for Mars to stay warm enough for liquid water to 
exist.  Mars lies at the far end of the "Goldilocks" band, at a distance 
from the sun where it's not so hot that water boils and not so cold it 
freezes.  In fact, even with the current Martian atmosphere, temperatures 
can approach freezing.  What a thicker atmosphere would do is to help hold 
in the heat (especially with the addition of a lot of CO2 and water vapor). 
 In addition, a thick atmosphere helps to distribute the heat better, 
helping keep the poles and night side of the planet a little warmer.

For further reading on this matter, I would actually suggest reading the 
science fiction books, Red Mars, Green Mars, and Blue Mars, by Kim Stanley 
Robinson.  Robinson has a very good appreciation for and understanding of 
the science involved in this process, and what he has written, while 
sometimes long-winded, seems to take into account the latest thinking on 
the issue of terra-forming Mars.  Plus, they're fun books to read!