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This project was funded by the National Science Foundation's Earth System History Program (ATM-9910172).
The Kilimanjaro ice cores provide a nearly continuous, high-resolution record of Holocene climate conditions for the last ~11.7 ka. Isotopic enrichment (suggesting warmer conditions) and reduced concentrations of major aerosol species such as Mg2+, Ca2+, SO42-, and NO3- (suggesting wetter conditions) dominate from ~11 to 4 ka. These data indicate that the ice fields formed during the well-documented African Humid Period when warmer and wetter conditions prevailed in response to the precession-driven increase in solar radiation. During this time interval, lakes in the region rose as much as 100 meters above their present levels and in sub-Saharan Africa lake expansion was spectacular with Lake Chad expanding 25-fold from ~17,000 km2 to cover an area between ~330,000 and 438,000 km2, comparable to that of the Caspian Sea today. After ~4 ka BP African lake levels dropped as conditions became cooler (more depleted δ18O) and drier (higher concentrations of the major aerosol species). The Kilimanjaro records capture the major African climate trends during the Holocene, as well as the larger scale trends in tropical temperature as inferred from their similarity to the Huascarán δ18O and dust records.
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Key paper:
Thompson, L. G., E. Mosley-Thompson, M. E. Davis, K. A. Henderson, H. H. Brecher,V.S. Zagorodnov, T. A. Mashiotta, P-N. Lin, V. N. Mikhalenko, D. R. Hardy and J. Beer, Kilimanjaro ice core records: Evidence of Holocene climate change in tropical Africa, Science, 298, 589-593, 2002.
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