This article deals with climatic reconstruction over a period of centuries, on the basis of indirect evidence found in historical and geographical sources. Histories, archives, local chronicles and journals of travellers and settlers contain references to lakes, landscapes, famines, droughts and floods, as well as occasional descriptions of climate and meteorological measurements. Such information can be combined with evidence from geology, palynology or the study of tree-rings to support hypotheses regarding climate and environment several centuries ago. This methodology is here described and used to reconstruct the trend of rainfall fluctuation in Africa over the past millennium. Two approaches are considered: the one seeks to determine absolute variation (thus assessing whether particular episodes were wetter or drier than today); the other focuses on short-term climatic anomalies (e.g. droughts) in which rainfall differed from the mean prevailing at the time, without seeking to relate them to present conditions. The results obtained from this study suggest that during the past millennium there have been two periods of relatively wet conditions in the semi-arid regions south of the Sahara: between the eighth and fourteenth centuries, and between the sixteenth and eighteenth centuries. Evidence for these episodes, and for synchronous fluctuations elsewhere in Africa is presented in the text. © 1979, Cambridge University Press. All rights reserved.
