The foregoing analysis of the nature of adaptive response to meteorological drought, and to the food shortages that have been closely associated with it in time, provokes the question of its future recurrence. To portray human communities solely as adaptors to exogenous events does not go far enough. However impressive the adaptive capabilities of such populations, the absence of any knowledge of future rainfall restricts individual choice to ad hoc decisions from year to year. This annual rhythm may obscure from view the possibility of longer-term trends, including that of ecological degradation (or desertification). Droughts are themselves contributory factors to such degradation. But so are anthropogenic factors, and increasing credence is being given to the view that land use may be linked with rainfall by means of ‘feedback’ mechanisms. For these societies, the roles of victim and agent are not easily distinguished. At this point, an examination of the climatological evidence is necessary, firstly as a pointer to the future significance of social adaptation, and secondly as a preliminary to a more systematic discussion of some evidence relating to desertification.

This chapter aims to review the related subjects of meteorological and hydrological drought. The most important questions concerning meteorological drought, from the standpoint of the present study, are (a) its persistence, (b) the possibilities for predicting its occurrence, and (c) the existence of feedback mechanisms.