A new diatom series with 1-6 year resolution from Lake Victoria, East Africa, shows that lake level minima occurred ca. 820-760, 680-660, 640-620, 370-340, and 220-150 calendar years BP. Inferred lake levels were exceptionally high during most of the 'Little Ice Age' (ca. 600-200 calendar years BP). Synchrony between East African high lake levels and prolonged sunspot minima during much of the last millenium may reflect solar variability's effects on tropical rainfall, but those relationships reversed sign ca. 200 years ago. Historical records also show that Victoria lake levels rose during every peak of the ca. 11-year sunspot cycle since the late 19th century. These findings suggest that, if these apparent tropical sun-climate associations during the last millenium were real, then they were subject to abrupt sign reversals.
Bibliographical noteFunding Information:
The SWD and conductivity series from P2K-1 will be archived with the World Data Center for Paleoclimatology, Boulder. Financial support for this project was provided by the National Science Foundation (ATM-9808972 and ATM-0117170) and Paul Smith’s College. Undergraduate students D. Grzesik, S. Hadam, C. Heimiller, and K. Przywara provided assistance in the field. J. Mills, R. Ogutu-Ohwayo, C. Ong, and M. Walsh provided logistical support and A.T. Grove, P. May-ewski, J.V. Sutcliffe, and D. Verschuren provided helpful discussions. Comments from three anonymous reviewers greatly improved the manuscript.
Copyright 2008 Elsevier B.V., All rights reserved.
- East Africa
- Lake victoria
- Solar variability
Continental Scientific Drilling Facility tags