TIMING OF THE YOUNGER DRYAS EVENT IN EAST-AFRICA FROM LAKE-LEVEL CHANGES

THE last deglaciation was interrupted by an abrupt cooling event, the Younger Dryas, at 11,000-10,000 yr BP (uncalibrated radiocarbon timesc ale)1. Originally recognized in climate records from northwest Europe, the Younger Dryas has now been identified in marine and ice-core reco rds worldwide2-6. In the tropics, a broadly contemporaneous change in climate is recorded by decreases in water levels and increased salinit y of lakes7-9,14, indicating a period of arid climate caused by a redu ction in ocean-to-land moisture flux. The exact timing of these change s in relation to the Younger Dryas event in high-latitude records has remained unclear, however. Here we present climate records based on an alyses of diatom assemblages, geochemistry and magnetic mineralogy of radio-carbon-dated sequences of laminated lake sediments from Lake Mag adi in the East African rift. These records provide a detailed record of climate change in lowland equatorial Africa throughout the last deg laciation (12,800-10,000 C-14 yr BP). We find that lake-level and humi dity maxima coincide with the most rapid phases of ice melting in the Northern Hemisphere, and that the climate changes, including the Young er Dryas event, were synchronous at low and high latitudes. Thus, the effects of abrupt climate change appear to be felt at both high and lo w latitudes without a significant time lag.