The Expanding Crisis

Deserts are spreading, and the process — desertification — puts the livelihoods of more than a billion people at risk. The main drivers:

• Overgrazing strips the plants whose roots hold soil in place, leaving bare, blowing dust
• Water depletion drains the rivers and aquifers that kept land alive
• Climate change pushes dry belts into ground that used to get rain

The Aral Sea is the warning: rivers feeding it were diverted for cotton, and it shrank into a toxic, salt-crusted plain.