We all know what a desert is: an arid, low-rainfall area with very little plant coverage. But what is desertification? Simply, it is the degradation of the land around deserts: the "drylands" that, with normal weather conditions and human use, can be cultivated and inhabited. These drylands, which cover 40 percent of the earth, are home to 2.3 million people in 100 countries. As drylands degrade, they become part of the neighboring desert: unproductive and unable to support the human and non-human populations that relied on them for survival. Adverse affects of desertification include widespread poverty as well as the degradation of rangeland and cropland.

Currently, the largest areas vulnerable to the effects of desertification are in sub-Saharan Africa and Central Asia. It is normal for these arid or semiarid regions to experience cycles of drought and rain, but the effects of global warming have changed these cycles, resulting in a longer dry season and a shorter growing season. When the rains do finally come, the land is often too parched to absorb it, creating runoff floods that are unable to impact the desiccated farms. 

Climate change certainly plays a role in desertification, but it is an oversimplification to say that global-warming-induced drought actually causes desertification. Rather, land abuse (usually over-farming and/or over-grazing) during times of drought causes the most damage. As the progress of desertification increases, people in the region typically respond by cultivating additional low productivity land or converting rangeland into cultivated land, thus further degrading the area.

Desertification is not a new phenomenon; in the 1930s, poor farming practices and a long-running drought turned the Great Plains of the United States into "the Dust Bowl," displacing thousands of Americans who had depended on farming for their livelihood. Better land and water management programs have brought agriculture back to the Great Plains, but the danger of desertification remains a very real threat for much of the world. In fact, one climate scientist uses the word "dust-bowlification" as better expressing the potential future effects of climate change and land mismanagement.

All desertification has far reaching consequences, from the loss of human life to strains on global resources. One area where desertification's effects are branching farther out from their source is in northern China, where deserts are expanding at a rate of 1,500 square miles per year. It is not only the 24,000 villages in the area that the desert has consumed; sandstorms regularly buffet the capital city of Beijing and have caused school and airport closures as far away as Japan and South Korea. 

The news is not all hopeless; desertification can be prevented through better environmental practices. Local management and macro policies are needed to promote sustainable practices in regions at risk. Since reversal of desertification once it has reached a certain point can be both difficult and expensive, most experts suggest preventative rather than restorative methods. See below for some ways to avoid or ameliorate desertification.