At the sixth session of the Interagency Working Group which was set up by the UN Conference on Desertification (UNCOD) to supervise and monitor the implementation of the UN Plan of Action to Combat Desertification, WMO was requested to arrange for the updating of the original document on Climate and desertification which has been prepared by Prof. F.K.Hare University of Toronto in 1977.
Given the importance of the interactions between climate and desertification, WMO accorded a major priority to this area and its action plan to combat desertification was first adopted in 1978 at the thirteenth session of the Executive Council of WMO and has gone through several revisions.

The widespread fear that the Earth's deserts are spreading was reawakened by the major 1968–73 drought in Sahelian West Africa, Sudan, Ethiopia, and parts of Kenya. There appears, however, to be no firm evidence that a permanent desiccation of the arid zone is in progress. Instead, the evidence suggests that ‘desertification’—defined as the spread of desert surfaces, regardless of cause—results more immediately from faulty land-use practices and their interaction with prolonged natural drought episodes.

Desertification appears to be a process of degradation of grassland, scrub, or savanna, ecosystems under the impact of overstocking or excessive cultivation. During periods of desiccation there is widespread destruction of perennial vegetation, compaction of soil (especially near watering places), and deflation of fine materials (wind erosion).

Such surfaces are lighter-coloured than native vegetation, and reflect more sunlight. This may enhance atmospheric subsidence, and hence intensify drought. Loss of surface organic litter may also act as a positive feedback for drought.

Prediction of such episodes is at least some years away, but three possibilities exist for such prediction: use of cyclical variations, where present; time-lagged teleconnections; and general circulation modelling.

Reduced infiltration in some arid areas, combined with excessive withdrawals in others, have lowered both shallow alluvial and deep fossil ground-water tables—in some areas to the point at which stock water-supply can no longer be maintained.
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