1. The two major causes of desertification are the climate variations and the human activities. The desertification is a process that is a growing concern in the world, as the deserts have been spreading out more and more. One of the reasons are the climate variations. The changes in the precipitation patterns have resulted in reduced precipitation levels at certain places, resulting in the dying out of the vegetation and gradually being replaced with barren land dominated by sand or rocks. The other major cause is the human activity. The humans have been destroying lot of the vegetation because of their own needs, as well as using the waters in the arid and semi-arid regions extensively, resulting in barren landscape with destroyed soil, quickly becoming desert or semi-desert.
2. The basic mechanism of desertification is the change in climate, which is triggering the reactivation of the dormant sand dunes. The climate is constantly changing, and that is not something new, and while it may have positive effects at certain places, it has negative ones in others. When the precipitation levels drop significantly at certain places, the vegetation is starting to die out, and to be replaced by a desert one. The soil is also getting downgraded significantly. This enables the winds to be much bigger factor in shaping the landscape. They start to pick up small particles from the barren land and disperse them, and as they do they create sand dunes gradually, creating a desert.
3. The adverse effects for the humans from the desertification are numerous. With the desertification, the areas become much less suitable for living, in certain occasions almost impossible. The soil is destroyed, thus the agriculture and farming of animals can not be performed, meaning that food can not be produced. The water reserves go significantly down, so there's not enough water for drinking or for the other needs of the humans. The winds are become a big problem, they are much stronger and often cause sand storms, which can even be deadly if someone is caught in the open. The climate is very harsh, the temperatures are very high and it is very dry, or if it is a cold desert, it will have both very high and very low temperatures, depending on the period of the year.
