Discuss the relative importance of human and physical causes of desertification. [15 marks]

Desertification is the expansion of dry desert conditions into areas that previously had not experienced them. This is characterized by lower soil productivity and a depletion of natural resources. There are both human and physical drivers of this process. Agriculture (overgrazing and over-abstraction of water), tree cutting, poor irrigation, population growth, and low economic development are all examples of human factors that may contribute. The main physical cause of desertification would be drought, which can reduce the vulnerability of soils to erosion. [A good evaluative point is that in all cases the climate regime sets the context in which the human factors can take hold, and could be argued to therefore be more important]