What happens when demand for this essential resource starts exceeding supply in many parts of the world?

The recent UN alert that drought in the Sahel threatens 15 million lives is a harbinger of things to come.

In the next twenty years, global demand for fresh water will vastly outstrip reliable supply in many parts of the world. Thanks to population growth and agricultural intensification, humanity is drawing more heavily than ever on shared river basins and underground aquifers. Meanwhile, global warming is projected to exacerbate shortages in already water-stressed regions, even as it accelerates the rapid melting of glaciers and snow cover upon which a billion people depend for their ultimate source of water.

This sobering message emerges from the first U.S. Intelligence Community Assessment of Global Water Security. The document predicts that by 2030 humanity's "annual global water requirements" will exceed "current sustainable water supplies" by forty percent. Absent major policy interventions, water insecurity will generate widespread social and political instability and could even contribute to state failure in regions important to U.S. national security. (Look here for a webcast from the Woodrow Wilson Center of experts and U.S. government officials discussing the findings.)