Is the food scarcity scare for real.

• Author: Brown, Lester R.
• Position: Ecology

IN RECENT MONTHS, rising oil prices have focused the world's attention on the depletion of vital reserves, but the drying up of underground water resources from overpumping is a far more serious issue. Excessive pumping for irrigation to satisfy food needs today almost guarantees a decline in food production tomorrow. There are substitutes for oil; the same cannot be said for water.

The growth in population since 1950 exceeds that during the preceding 4,000,000 years. Perhaps more striking, the world economy has expanded sixfold since 1950. As the economy grows, its demands are outstripping the Earth, exceeding many of the planet's natural capacities to provide food, water, and the basic needs of daily living. Evidence of these excessive demands can be seen in collapsing fisheries, shrinking forests, expanding deserts, escalating C[O.sub.2] levels, eroding soils, elevated temperatures, disappearing species, falling water tables, melting glaciers, deteriorating grasslands, rising seas, and rivers that are running dry. Nearly all these environmental trends affect world food security.

Two of the newer trends--falling water tables and rising temperatures--are making it far more difficult for the world's farmers to feed the 76,000,000 people added to our numbers each year. Humans drink nearly four quarts of water a day in one form or another, but the food we consume on a daily basis requires 2,000 quarts of water to produce. Agriculture is the most water-intensive sector of the economy: 70% of all water pumped from underground or diverted from rivers is used for irrigation; 20% is employed by industry; and 10% goes to residences.

Water tables currently are falling in countries that contain over half the world's people. The vast majority of the nearly 3,000,000,000 individuals to be added to world population by mid-century will come in nations where water tables already are falling and wells are going dry. Historically, it was the supply of land that constrained the growth in food production. Today, though, the shortage of water is the most formidable barrier.

Rising temperatures are the second big threat to future food security. During the last few years, crop ecologists focusing on the precise relationship between temperature and crop yields have found that each 1[degrees]C rise in temperature during the growing season reduces the yield of grain--wheat, rice, and corn--by 10%. Since 1970, the Earth's average temperature has risen nearly...