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155,000 Years of West African Monsoon and Ocean Thermal Evolution

Annual SSS in the Gulf of Guinea.
Figure 1. Annual SSS in the Gulf of Guinea, MD03-2707 core location, and drainage basin of Niger and Sanaga rivers. Click for full figure.

155,000 Years of West African Monsoon and Ocean Thermal Evolution

Science
Vol. 316, pp. 1303-1307, 1 June 2007, doi:10.1126/science.1140461.

Syee Weldeab1,2, David W. Lea1, Ralph R. Schneider3, Nils Andersen4

1 Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, CA 93106-9630, USA

2 Present address: Leibniz Institut für Meereswissenschaften an der Universität Kiel (IFM-GEOMAR), Germany

3 Institut für Geowissenschaften, Universität Kiel, Germany.

4 Leibniz-Labor für Altersbestimmung und Isotopenforschung, Universität Kiel, Germany.
ABSTRACT:
A detailed reconstruction of West African monsoon hydrology over the past 155,000 years suggests a close linkage to northern high-latitude climate oscillations. Ba/Ca ratio and oxygen isotope composition of planktonic foraminifera in a marine sediment core from the Gulf of Guinea, in the eastern equatorial Atlantic (EEA), reveal centennial- scale variations of riverine freshwater input that are synchronous with northern high-latitude stadials and interstadials of the penultimate interglacial and the last deglaciation. EEA Mg/Ca-based sea surface temperatures (SSTs) were decoupled from northern high- latitude millennial-scale fluctuation and primarily responded to changes in atmospheric greenhouse gases and low-latitude solar insolation. The onset of enhanced monsoon precipitation lags behind the changes in EEA SSTs by up to 7000 years during glacial-interglacial transitions. This study demonstrates that the stadial-interstadial and deglacial climate instability of the northern high latitudes exerts dominant control on the West African monsoon dynamics through an atmospheric linkage.
Download data from the WDC Paleo archive:
Gulf of Guinea Core MD03-2707 d18O and Mg/Ca Data and SST/SSS Reconstructions,
Text or Excel format.

To read or view the full study, please visit the Science website.
It was published in Science, Vol. 316, pp. 1303-1307, 1 June 2007, doi:10.1126/science.1140461.
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