Desertification is caused by

temperature variations

human activity

solar heating patterns

leaching of the soil

Answer: temperature variations, human activity, leaching of the soil

Explanation:

Desertification is a kind of land degradation process which is seen in drylands. In this process the temperature or weather condition of a region is severely affected this is associated with low annual rainfall, the soil looses moisture and is subjected to wind erosion. Human activity also contributes to the desertification due to clear cutting of the land and clearing up of the vegetation as a result of this the soil looses it's productivity due to erosion. Leaching is a process of loss of water soluble minerals from the soil which will also cause desertification.