Dear EarthTalk: Can you explain what "desertification" is and why it is an important environmental issue?


— Jay Harris, Nashville, Tenn.

Desertification is the degradation of land in already dry parts of the globe that results from various factors, including natural climate changes as well as human activity. As the name connotes, it is the expansion of desert-like conditions which render useless land that was once biologically and/or economically productive.

According to the United Nations' Convention to Combat Desertification, the phenomenon occurs in "drylands" (arid, semi-arid and dry sub-humid areas) on all continents except Antarctica and affects the livelihoods of millions of people, including a large proportion of the world's poor.

Drylands constitute about 40 percent of the world's total land area, and are home to some 2 billion people—a third of human population.


The United Nations estimates that 10 to 20 percent of the world's drylands are already degraded to the point where desertification is an imminent threat.



Other governments also are taking steps to keep desertification in check.

China is working to create a 2,800-mile forest belt that will not only block the fast advancing sands of the Gobi desert but serve as a "carbon sink," as well, to absorb greenhouse gas emissions.



Historians point to the Dust Bowl of the 1930s as proof positive of America's susceptibility to such problems. Lessons learned then led to the creation of the Soil Conservation Service—now called the Natural Resources Conservation Service—to teach farmers and other landowners agricultural practices that reduce soil loss and maintain biological diversity around agricultural operations. In spite of such efforts, desertification still plagues parts of the U.S. today. The hope today is that global warming won't tip us to the point where have to learn some hard lessons all over again.
