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Science 1 June 2007:
Vol. 316. no. 5829, pp. 1303 - 1307
DOI: 10.1126/science.1140461
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Research Articles

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

Syee Weldeab,1*{dagger} David W. Lea,1 Ralph R. Schneider,2 Nils Andersen3

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.

1 Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, CA 93106–9630, USA.
2 Institut für Geowissenschaften, Universität Kiel, Germany.
3 Leibniz-Labor für Altersbestimmung und Isotopenforschung, Universität Kiel, Germany.

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

{dagger} To whom correspondence should be addressed. E-mail: sweldeab{at}ifm-geomar.de

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Atlantic Forcing of Persistent Drought in West Africa.
T. M. Shanahan, J. T. Overpeck, K. J. Anchukaitis, J. W. Beck, J. E. Cole, D. L. Dettman, J. A. Peck, C. A. Scholz, and J. W. King (2009)
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Record of climate-driven morphological changes in 376 Ma Devonian fossils.
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