PAGES Kenya

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A 6 m core from the Crescent Island Crater (CIC) Basin, Lake Naivasha, Kenya describes the hydrological response of Lake Naivasha to a succession of decade-scale fluctuations in the regional balance of rainfall and evaporation in equatorial East Africa (Figure 1) (Verschuren et al., 2000). There was significantly drier climate than today during the Medieval Warm Period (MWP, ca. AD 1000 to 1270) and a relatively wet climate during the Little Ice Age (LIA, AD 1270 - 1850) which was interrupted by three prolonged dry episodes. The MWP period of inferred African aridity and all three severe drought events of the past 700 years were broadly coeval with phases of high solar radiation, and intervening periods of increased moisture were coeval with phases of low solar radiation (Verschuren et al., 2000). Verschuren et al. (2000) compared their record with the pre-colonial history of east Africa recounted in oral traditions, and found evidence that in the six centuries before AD 1895, there was drought-induced famine, political unrest and large-scale migration of indigenous peoples, temporally matching the three lake-recorded drought periods.

Fig.1: Changing lake level in Lake Naivasha, Kenya as inferred from the sediment record is superimposed with a rough reconstruction, based on oral histories, of societal prosperity in the region (Verschuren et al. 2000).

Refereces:
Verschuren D., Kathleen R.L. and Cumming B.F. (2000) Rainfall and drought in equatorial east Africa during the past 1,100 years. Nature, 403: 410-413.