Contrary to popular belief, desertification is not the expansion of deserts. It is the degradation of land in arid, semi-arid and dry sub-humid areas caused mostly by human activities and climactic variations.
One third of the world’s land surface is covered by dryland ecosystems. These areas are very fragile and react strongly to inappropriate land use.
More than 250 million people worldwide are affected by desertification. The real cause for alarm is that another one billion people are at risk, residing in over 100 countries.
Over 70 percent of the world’s drylands (excluding hyper-arid deserts) are degraded.
Not all consequences of the degradation of drylands are felt by those inhabiting the drylands themselves. Dust storms and air pollution are often a result of degraded drylands and negative impacts were felt at long distances in cases such as the Dust Bowl years in the United States, the Virgin Land scheme area of the former Soviet Union in the 1950s and in the African Sahel in the 1970s and 1980s.
It is estimated that the negative impact to annual incomes in areas directly affected by desertification is approximately USD$42 billion per year. And this number only takes into account the “direct” costs.
United Nations Convention to Combat Desertification website
Source: UNESCO Water Portal, June 2007