Well desertification is a very interesting problem. But basically there is natural desertification and there is accelerated desertification caused by the growth

Well desertification is a very interesting problem. But basically there is natural desertification and there is accelerated desertification caused by the growth of population (misuse of lands, overuse of farm lands, deforestation, rapid growth of population, etc). In northern part of China, the government and locals plant trees to slow down and even able to recover lands from desertification. But the progress is slow... although South America is still full of trees, scientists are already seeing rapid desertification because we are destroying the nature.