Many countries are facing dangerous water shortages. As world
demand for food has soared, millions of farmers have drilled too
many irrigation wells in efforts to expand their harvests. As a
result, water tables are falling and wells are going dry in some
20 countries containing half the world’s people. The overpumping
of aquifers for irrigation temporarily inflates food production,
creating a food production bubble that bursts when the aquifer
is depleted. The shrinkage of irrigation water supplies in the
big three grain-producing countries — the United States, India,
and China — is of particular concern. Thus far, these countries
have managed to avoid falling harvests at the national level,
but continued overexploitation of aquifers could soon catch up
with them. In most of the leading U.S. irrigation states, the
irrigated area has peaked and begun to decline. In California,
historically the irrigation leader, a combination of aquifer
depletion and the diversion of irrigation water to fast-growing
cities ha