The Coming Water Crisis

The United Nations warns that around half the world's population already faces water stress for at least part of the year. The squeeze comes from how little water we can actually reach: freshwater is just 2.5 percent of all water on Earth, and most of that is locked in ice caps and glaciers. The supply we can tap — rivers, lakes, and shallow groundwater — is less than 1 percent of the total.

Agriculture consumes roughly 70 percent of global freshwater withdrawals, and that demand is rising with population growth. Aquifers that took millennia to fill — like the Ogallala under the US Great Plains — are being drained far faster than they recharge.