Outgrowing the Earth: The Food Security Challenge in an Age of Falling Water Tables and Rising Temperatures


Lester R. Brown

Chapter 5. Protecting Cropland: Advancing Deserts


Roughly one tenth of the earth’s land surface is used to produce crops. Two tenths is grassland of varying degrees of productivity. Another two tenths is forest. The remaining half of the land is either desert, mountains, or covered with ice. The area in desert is expanding, largely at the expense of grassland and cropland. Deserts are advancing in Africa both north and south of the Sahara and throughout the Middle East, the Central Asian republics, and western and northern China. (See Table 5–2.) (The effect of desertification on China’s food production is discussed in more detail in Chapter 8.) 18

Nigeria, Africa’s most populous country, is losing 351,000 hectares of rangeland and cropland to desertification each year. While Nigeria’s human population has increased from 30 million in 1950 to 130 million in 2004, a fourfold expansion, its livestock population has grown from roughly 6 million to 65 million head, a tenfold increase. With the forage needs of Nigeria’s 15 million head of cattle and nearly 50 million sheep and goats exceeding the sustainable yield of the country’s grasslands, the country is slowly turning to desert. 19

The government of Nigeria considers the loss of productive land to desert to be far and away its leading environmental problem. No other environmental change threatens to undermine its economic future so directly as the conversion of productive land to desert. Conditions will only get worse if Nigeria continues on its current population trajectory toward 258 million people by 2050. 20

In the vast swath of Africa between the Sahara Desert and the forested regions to the south lies the Sahel. In countries from Senegal and Mauritania in the west to Sudan, Ethiopia, and Somalia in the east, human and livestock pressures are converting more and more land into desert. 21

A similar situation exists along the Sahara’s northern edge, the tier of largely semiarid countries across the top of Africa. Algeria, in particular, is being squeezed between the Mediterranean Sea and the Sahara Desert as the latter advances northward. In a desperate effort to halt this encroachment, Algeria has decided to convert the southernmost 20 percent of its grainland to perennial crops, such as olive orchards or grape vineyards, that will hold the soil better. Whether this will halt the advancing desert remains to be seen. At a minimum, it will be a difficult sacrifice in a country that already imports 40 percent of its grain. 22

Some of the most severe desertification found anywhere is in China, where 360,000 hectares of land become desert each year. In parts of northern and western China, deserts have expanded to the point where they are beginning to merge. In China’s Xinjiang Province, the huge Taklamakan and the smaller Kumtag deserts are approaching each other and appear headed for a merger. On the southwestern edge of Inner Mongolia, the 5-million-hectare (12-million-acre) Bardanjilin desert is moving toward the 3-million-hectare Tengry desert. 23

In these regions of desert expansion, sandstorms are common, often forcing the abandonment of villages. Keeping highways passable becomes a major challenge as sand dunes advance across roadways. Keeping power lines and telephone lines above the drifting sand is itself a challenge. Special crews periodically follow the phone lines across the countryside looking for poles that may be about to be inundated with drifting sand. They then extend the poles to make sure the lines remain above the sand. But a few months later, the sand may be blown away, leaving the wires suspended far above the ground.(Photos of desertification.)24


Table 5-2. Selected Examples of Desertification Around the World
Country Extent of Desertification

In the Sistan basin, windblown dust and sand have buried more than 100 villages. In the northwest, along the Amu Darya River, a sand dune belt that is some 300 kilometers (186 miles) long and 30 kilometers wide is advancing by up to 1 meter a day.


Approximately 58 million hectares of land have been affected. Economic losses associated with desertification are estimated at $300 million a year.


Nationwide, deserts are expanding by 360,000 hectares (889,000 acres) a year. Some 400 million Chinese are affected by the suffocating dust storms of late winter and early spring.

India Various forms of desertification affect 107 million hectares, one third of India’s land area.

In the eastern provinces of Baluchistan and Sistan, some 124 villages have been buried by drifting sand.


More than 80 percent of its land is vulnerable to desertification, affecting up to a third of the country’s 32 million people and half its livestock.

Mexico Some 70 percent of its land is vulnerable to desertification. Land degradation prompts some 700,000 Mexicans to leave the land each year in search of jobs in nearby cities or in the United States.
Nigeria Each year 351,000 hectares of land are lost to desertification, affecting each of the 10 northern states.
Yemen Some 97 percent of the land in this country of 19 million people shows some degree of desertification.
Souce: See endnote 18.

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