The following is from the environmental themed advice column EarthTalk®, by the Editors of the non-profit publication E/The Environmental Magazine, that we’ll be regularly featuring here on CL’s Green Community.

Dear EarthTalk: Can you explain what “desertification” is and why it is an important environmental issue? — Jay Harris, Nashville, TN

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 two billion people—a third of human population. Water scarcity in existing drylands makes it difficult for plants, animals and humans to thrive there; desertification makes it impossible, forcing those affected to flee to more hospitable lands, whether they are welcome or not. The United Nations estimates that 10-20 percent of the world’s drylands are already degraded to the point where desertification is an imminent threat.