The termination of the African Humid Period (AHP) about 5 thousand years ago (ka) was the most dramatic climate shift in northern and equatorial Africa since the end of the Pleistocene. Based on TEX 86 paleotemperature data from Lake Turkana, Kenya, we show that a temperature shift of 2-4°C occurred over the two millennia spanning the end of the AHP, with the warmest conditions occurring at ~5ka. We note a similar shift, though of a smaller magnitude, in other East African temperature records from Lakes Malawi and Tanganyika, as well as Mt. Kilimanjaro. Additionally, we document the temperature history for the last 220 years from Lake Turkana that indicates the thermal anomaly at 5ka was warmer than the present day Lake Turkana temperatures and on par with modern temperatures of Lakes Tanganyika and Malawi. We suggest that the thermal response at the end of the AHP may be linked to local insolation during September-November, when local air temperature rises to an annual maximum over Lakes Malawi and Tanganyika and a secondary maximum over Lake Turkana and Mt. Kilimanjaro. September-November insolation peaked at ~5ka and likely caused air and water temperatures in the region to rise to maxima at that time.
Bibliographical noteFunding Information:
We thank LacCore, the National Repository for Lake Sediment Cores at the University of Minnesota for core access and assistance. E.T. Brown, S. Colman, and Z. Liu provided useful comments on an earlier version of the manuscript. We thank Ellen Hopmans, Jort Ossebaar, Sarah Grosshuesch, Julia Halbur, and Doug Klotter for laboratory assistance. This research was funded by Grant NA-060-AR4310113 from the U.S. Department of Commerce, National Oceanic and Atmospheric Administration . Support from the Gledden Fellowship to J.P.W. is acknowledged. Work prepared while J.P.W. on leave at the Center for Water Research, University of Western Australia and the WA-Organic & Isotope Geochemistry Center, Curtin University of Technology. This work forms contribution 2402-JW at the Center for Water Research, The University of Western Australia.
Copyright 2012 Elsevier B.V., All rights reserved.
- African Humid Period
- Lake Turkana