Palynological evidence for abrupt climatic cooling in equatorial Africa at about 43,000–40,000 cal BP

Abstract

The same basal sequence of two pollen zones is found in three previously published pollen diagrams for widely separated sites situated along highlands adjacent to the Albertine Rift in equatorial Africa. Here evidence is presented that is supportive of the hypothesis that the transition between the zones was contemporaneous at all sites and dates to about 43,000–40,000calBP. Environmental interpretation of the sequence indicates that there was a major fall in temperature, depressed temperature thereafter persisting until the transition to the postglacial at 14,000–11,500calBP. The climate also became drier. Well-dated sediments of this age are rare in equatorial Africa, so comparisons are scarce. However, there is some evidence from the Eastern Arc Mountains, Tanzania, of a similar climatic event at about the same time. Farther afield, there is good evidence for abrupt climatic deterioration at ~40,000calBP in western Eurasia, where there was accompanying cultural change. Sedimentary basins along the Albertine Rift-margin highlands are especially well suited for palynologically-based investigations of past temperatures. Their relatively well-defined catchment areas result in reduced inputs of pollen derived from vegetation growing under different climatic conditions.