Phenomenon of desertification

Deserts are dry areas with few plants and can be conveniently separated from other vegetation types on the basis of rainfall and temperature. They are found where mean annual rainfall is below about 50 mm and mean annual temperature is above 15 °C. The term desertification was used initially (1949) in reference to the increasing extension of deserts into semi-arid lands. In the 1980s and 1990s, authorities have begun to question the extent or even existence of the desertification problem. The term desertification may imply a ‘once and for all’ process on a massive scale, but what seems to happen on the ground (in areas where desertification appears to be occurring) is the development of areas of land degradation, in some cases quite severe, but which with care and two or three good rainy seasons might return to their former status.

Here is the suggestion, discussed by J. A. Binns in ‘Is desertification a myth?’ (Geography 75:106–13 (1990)), that the phenomenon is linked with lack of rainfall (i.e. drought) and land utilisation of a kind that damages the environment. Perhaps the critical point, which is rarely stressed, is that the degradation (desertification) occurs in areas where rainfall is usually sufficient to support at least a sparse vegetation cover.

The ‘approximate desert boundaries’ in the Sudan (see figure 4.1) suggest the desert in Sudan moved south by about 120 km between 1958 and 1975.