How Green Is My Desert?

Part of the Water: H2O = Life exhibition.

Al Ain oasis, Abu Dhabi
© Heeb / AGE Fotostock

Dry lands--places where rainfall is scarce and evaporation is high--have been crucial incubators of human culture. But deserts are precarious places for cities, and many of the ancient dry land settlements--Chaco Canyon in New Mexico, Sumer in Iraq--are now only ruins visited by archaeologists and tourists.

Today, new cities are appearing in arid regions around the world. In aerial photos these desert cities may look like mirages . . . and perhaps they are. The price of watering our deserts can include destruction of the fragile desert ecosystem, groundwater depletion, and lowered rivers. Can we keep that up indefinitely?

The World's Deserts

Deserts, today cover about 25 percent of Earth's surface. More than 500 million people live in deserts and dry lands.

"Whiskey is for drinking; water is for fighting over."
 --Attributed to Mark Twain

Saudi Arabia Desert
Courtesy of the TopSat Consortium © QinetiQ

Farm, United Arab Emirates
Population 4,444,011 (2007)
Annual rainfall 120mm (5 inches)

Scottsdale, Arizona
Population 230,000 (2006)
Average yearly rainfall 210 mm (8 inches)

Las Vegas, Nevada
Population 1,820,232 (2006)
Average yearly rainfall 120mm (5 inches)

Mesa County, Colorado
Population 134,189 (2006)
Average yearly rainfall 203 mm (8 inches)

Farm, Saudi Arabia
Population 27,601,038 (2007)
Average yearly rainfall 100mm (4 inches)

Tucson, Arizona
© VisionsofAmerica / Joe / AGE Fotostock

Population 1.4 million (2006)
Annual rainfall 100-200 (4-8 inches)

Tucson, Arizona
Population 518,956 (2006)
Average yearly rainfall 300mm (12 inches)

Al Ain oasis, Abu Dhabi
Population 348,000 (2003)
Average yearly rainfall 361mm (14 inches)

Palm Springs, California
Population 47,806 (2006)
Average yearly rainfall 150mm (6 inches)