East Africa's enormous Lake Victoria dried out at the close of the last glacial, but the precise timing and origin of that drying event have not been clarified, largely because of uncertainty regarding core stratigraphy and ancient carbon effects on 14C dates from the lake. New dates and re-examination of evidence from widely distributed cores shows that desiccation occurred some time between 15 900 and 14 200 calendar years BP, and perhaps also ca. 18-17 kyr BP. These lake level minima were briefer than has been previously suggested and were synchronous with pronounced global climate disruptions including North Atlantic ice-rafting Heinrich event 1. Less severe declines occurred during the Older and Younger Dryas intervals. Dansgaard-Oeschger type cooling cycles registered in the GISP2 ice core record tracked major lake level regressions in East Africa and weakenings of Afro-Asian monsoons during the late Quaternary, possibly linking the desiccation of Lake Victoria to century-scale reductions in solar radiation output.
Bibliographical noteFunding Information:
We thank E. Bard, F. Gasse, T. Johnson, K.-L. Knudsen, S. Romme, M.-S. Seidenkrantz, and M. Talbot for helpful discussions, and FIRRI, D. Grzesik, S. Hadam, C. Heimiller, ICRAF, D. Livingstone, the National Science Foundation, C. Ong, R. Ogutu-Ohwayo, Paul Smith’s College, K. Przywara, and M. Walsh for financial and technical support.
Copyright 2011 Elsevier B.V., All rights reserved.
- Dansgaard-Oeschger cycles
- Heinrich events
- Lake Victoria
- Solar variability
- Younger Dryas