谁能给一篇关于荒漠化带来的影响的文章，用英文的，两百字左右，要全面

About 3.6 billion of the world's 5.2 billion hectares of useful dryland for agriculture has suffered erosion and soil degradation. In more than 100 countries, 1 billion of the 6 billion world population is affected by desertification, forcing people to leave their farms for jobs in the cities.
Desertification takes place in dryland areas where the earth is especially fragile, where rainfall is nil and the climate harsh. The result is the destruction of topsoil followed by loss of the land's ability to sustain crops, livestock or human activity. The economic impact is horrendous, with a loss of more than billion per year in agricultural goods and an increase in agricultural prices.

Climatic changes can trigger the desertification process, but human activities frequently are the proximate cause. Overcultivation exhausts the soil. Deforestation removes trees that hold the soil to the land. Overgrazing of livestock strips the land of grasses. According to a UN s