PHYSICAL CAUSE
▪ Reduced Precipitation - As vegetation dies, the protective layer it provided for the soil will also be removed. As a result, the soil will be increasingly exposed to wind and rain, which will accelerate the rate of soil erosion, leading to worsening soil conditions. This may cause a positive feedback loop of worsening soil condition and vegetation death, leading to desertification.
▪ Global Warming - The rise in average climatic temperatures will increase the rate of evaporation of water moisture, especially in tropical and sub-saharan climates. If more moisture has evaporated, less will be available for convectional rainfall, and so plant growth will be stunted and vegetation dies (leading to desertification as described above).