Desertification is the spread or encroachment of a desert environment into arid or semiarid regions. It is caused by climatic changes, human influence or a combination of both. Climatic factors include temporary but severe drought periods and long term climatic changes resulting in aridity. Artificial changes in climate caused by human interferences such as the removal of vegetation (which can cause unnaturally high erosion), over-cultivation of land and excessive use of surface and groundwater are human factors that can result in desertification.
Desertification is the draining of the life-supporting capabilities of arid or semiarid land. Characteristic of this process is the declining of the groundwater table and depletion of surface water supplies, the salinisation of water and topsoil, increasing erosion and diminution of natural vegetation. Drought or misuse by humans makes land susceptible to desertification which spreads into arid and semiarid areas. Desertification can also occur within deserts when the ecological balance is disturbed, for example in the Sonoran and Chihuahuan deserts of the American Southwest.
Public awareness of desertification has increased in the late 20th century as more and more people and land are affected.