Holocene variations in the level of Lake Bosumtwi, Ghana

Abstract

RECENT surveys of the changing climate of Africa during the Late Quaternary have shown that although a reasonably well established climatic sequence is now available for some parts of the continent, there exist very large areas which have yet to yield any well-dated, unequivocal palaeoclimatic data1–3. Most notable among the latter are the lowland tropical forest regions. Despite the absence of information from such critical areas, attempts have been made to reconstruct atmospheric conditions over West Africa during the Late Quaternary2,4,5, but obviously no uniformly satisfactory models can be produced until these data gaps have been filled. Study of changing lake levels has proved a particularly valuable palaeoclimatic tool3 and we report here the first 14C dates of former levels of a lake that lies within the present lowland forest zone of West Africa. Our work indicates that lakes of the humid tropics can provide valuable palaeoclimatological information that may be less apparent from the study of arid zone lakes. In particular, we present evidence suggesting that major regressions of equatorial African lakes during the Holocene, rather than being a consequence of exceptional aridity, may have occured during periods of slightly higher temperatures and greater evaporation.