Land degradation, such as a spread of deserts in parts of Africa, costs the world economy trillions of dollars a year and may drive tens of millions of people from their homes, a U.N.-backed study said on Tuesday.
Worldwide, about 52 percent of farmland is already damaged, according to the report by The Economics of Land Degradation (ELD), compiled by 30 research groups around the world.
It estimated that land degradation worldwide cost between $6.3 trillion and $10.6 trillion a year in lost benefits such as production of food, timber, medicines, fresh water, cycling of nutrients or absorption of greenhouse gases.
"One third of the world is vulnerable to land degradation; one third of Africa is threatened by desertification," it said.