How do changing climates affect the water cycle (snow, rain, runoff)?
* A: Changing climates influence the water cycle by influencing factors such as surface temperatures and evapotranspiration rates, precipitation patterns, proportions of precipitation received as rain versus snow, and amount and timing of runoff. Increased temperatures lead to more precipitation falling as rain rather than snow, earlier snowmelt and snowmelt-driven streamflow, and reduced spring snowpack. For the mountainous regions of the Western United States, snowmelt provides approximately 70 percent of annual streamflow. Thus, reduced spring snowpack leads to reduced summer streamflow in these regions. (Mote 2003, Mote et al. 2005, Mote et al. 2008, Stewart et al. 2005).
