Wherever there is a shortage of rain over a long period of time, there is drought. Drought affects plants, animals, and people. It is an especially serious problem for farmers and for the people who depend on the crops they produce.

Where drought occurs

Deserts are sometimes said to be in a permanent drought because they receive very little rain year-round. However, drought does not happen only in very dry places. It may occur almost anywhere in the world, in many different types of climates. Places that have a rainy season and a dry season have seasonal drought during the dry season. The type of drought called unpredictable drought affects any place that receives an abnormally low amount of rain for an extended time period.

Causes

Drought results from changes in the Earth's atmosphere that interfere with the normal pattern of rainfall. Some droughts are caused by shifts in the winds that normally bring rain to an area. Others are caused by changing ocean currents, which affect the temperature and moisture of the air. For example, the warm Pacific Ocean current called El Niño causes changes in air temperature that create droughts in parts of Australia, Indonesia, and South America.

Effects

Drought kills natural vegetation, causes crops to fail, and reduces water supplies. Water levels go down in lakes and even in wells. Rivers shrink and streams sometimes dry up entirely. The dry soil cracks and may be blown by the wind, which creates dust storms. Forest or grass fires start easily and spread rapidly.

Severe droughts can last for months or years and kill many people and livestock. People may die of famine, or lack of food. Other people, weakened by hunger, die from disease. Between 1876 and 1879 drought caused at least 9 million deaths in North China. About 5 million people died from drought in India during almost the same years. In the 20th century drought killed millions of people in China, India, the Soviet Union, and the countries of the African region called the Sahel, south of the Sahara.

Severe droughts often force people and animals to move, sometimes permanently, to find water. Some farmers go to places where they think conditions will be better for their crops and livestock. In the United States during the 1930s a drought forced thousands of families to leave their homes on the Great Plains. The area that was affected became known as the Dust Bowl because so much of the soil dried up. Some people affected by drought give up farming altogether and move to cities to find other types of work.