Mars is frozen today, but when it was young there may have been liquid water on its surface. What does the latest evidence indicate about the ancient martian climate? At the recent Astrobiology Science Conference (AbSciCon) 2010, Jim Kasting of Penn State and Brian Toon of the University of Colorado discussed the possibility of a warm and wet Mars. A primary point of debate was whether or not physical features on the surface of Mars required extended warm, wet periods to form, or if short-term warming generated by impacts was enough.