People in the developing world are particularly vulnerable to drought-related suffering. These are just a few examples. Afghanistan: Scarcity of food and drinking water is a recurring problem. India and Pakistan: Dry spells spur deterioration of health and sanitary conditions. Kenya: Chronic water shortages result in loss of livestock. Somalia: Insufficient rain means poor harvests. Then, malnutrition increases, people lose jobs, and the economy suffers.

Droughts change history. Researchers link a 300-year drought that struck Mesopotamia about 4,000 years ago to the collapse of the Akkadians, who ruled the world's first great empire. Historians also blame droughts for the disappearance of pre-Inca civilizations in Latin America.

	Drought and dust storms ruined this South Dakota farm during the 1930s. Source: NOAA Photo Library

No one knows how frequently catastrophic droughts occur. Earth has endured them since at least the end of the Ice Age. In recent history, major droughts seem to appear twice a century or more.

Deforestation and other human activities could make droughts more common. In parts of Africa, for example, people cleared coastal forests. They then noticed that inland regions received far less rainfall. Scientists suspect that this happened because there were no longer enough trees to "recycle" rainfall by releasing water vapor. Researchers predict that another catastrophic drought, perhaps lasting for decades, will grip Tropical Africa within the next 50 to 100 years.

Almost one-third of all land on Earth is already arid or semiarid. Any period of reduced rainfall can create real problems in these areas.

Visit the Middle East for a cruise down the River Jordan, a lifeline for the country of Israel. Options: 56k | 220k (RealPlayer required) Source: Journey to Planet Earth

Every year, a severe drought affects some part of the United States. One of the worst came in 1988. The Midwest and Rockies got only 15 to 50 percent of their normal rainfall. Forest fires raged, burning more than a third of Yellowstone National Park.

Yellowstone fire, 1988. Source: National Park Service

Whether a drought lasts for days or decades, it can damage crops and create water shortages. Drought is the most serious threat to agriculture throughout the world.

In industrialized countries, droughts are usually an inconvenience rather than a threat to survival. Food and drinking water can often be brought in from other places. For developing countries, however, droughts can be devastating. Prolonged dry spells can cause people's livelihoods—and perhaps even their lives—to shrivel up.

What are the health consequences of drought?