Groundwater

Thirty million people in the American West depend on snowmelt to grow food, slake their thirst, and run their towns, cities, and industries. Twenty-two million of them live in Southern California. As in many parts of the world, western water supplies are over-allocated and populations are growing. Increasing variability in precipitation—the primary impact of climate change on the hydrologic cycle—exacerbates the stress: longer droughts, less snowpack, and earlier snowmelt are already observable. Current climate models estimate that 70 percent of western snowpack will be gone by 2100.