A recent study by MIT scientists shows that the supply of fresh water could increase under global warming.  The warmer conditions are expected to speed up the global water cycle, leading to more rainfall in many areas.  The scientists estimate that it could increase by 15 percent over the whole globe.  However, there are many other factors which might affect water availability, including population increases and relocations, changes in the phase (snow to rain) or timing of precipitation events which could still affect water supplies locally.  You can read the story by clicking here.