The recovery of detailed and continuous paleoclimate records from the interior of the African continent has long been of interest for understanding climate dynamics of the tropics, and also for constraining the environmental backdrop to the evolution and spread of early Homo sapiens. In 2005 an international team of scientists collected a series of scientific drill cores from Lake Malawi, the first long and continuous, high-fidelity records of tropical climate change from interior East Africa. The paleoclimate records, which include lithostratigraphic, geochemical, geophysical and paleobiological observations documented in this special issue of Palaeo3, indicate an interval of high-amplitude climate variability between 145,000 and ~60,000years ago, when several severe arid intervals reduced Lake Malawi's volume by more than 95%. These intervals of pronounced tropical African aridity in the early Late Pleistocene around Lake Malawi were much more severe than the Last Glacial Maximum (LGM), a well-documented period of drought in equatorial and Northern Hemisphere tropical east Africa. After 70,000years ago climate shifted to more humid conditions and lake levels rose. During this latter interval however, wind patterns shifted rapidly, and perhaps synchronously with high-latitude shifts and changes in thermohaline circulation. This transition to wetter, more stable conditions coincided with diminished orbital eccentricity, and a reduction in precession-dominated climatic extremes. The observed climate mode switch to decreased environmental variability is consistent with terrestrial and marine records from in and around tropical Africa.
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Many individuals and organizations contributed to the successful planning and execution of the field program, as well as the analyses and support for analytical phases of the project. Especially, we thank the people and government of Malawi for permission to conduct this research, and in particular the Geological Survey of Malawi for local assistance and participation. Numerous individuals from key contractors worked tirelessly in order to complete the program, including the following: Lengeek Vessel Engineering; ADPS dynamic positioning and ship's crew; the drilling team from Seacore Ltd; DOSECC, and LacCore for assistance with core analysis and archiving. We thank the US-NSF Earth System History and Paleoclimate programs, and the International Continental Scientific Drilling program for financial support.
Copyright 2011 Elsevier B.V., All rights reserved.
- East African rift
- Lake level change
- Lake Malawi
- Scientific drilling