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Science 2 February 2007:
Vol. 315. no. 5812, pp. 637 - 639
DOI: 10.1126/science.1134839
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Reports

Rapid 20th-Century Increase in Coastal Upwelling off Northwest Africa

H. V. McGregor,1*{dagger} M. Dima,2,3 H. W. Fischer,4 S. Mulitza1,5

Near-shore waters along the northwest African margin are characterized by coastal upwelling and represent one of the world's major upwelling regions. Sea surface temperature (SST) records from Moroccan sediment cores, extending back 2500 years, reveal anomalous and unprecedented cooling during the 20th century, which is consistent with increased upwelling. Upwelling-driven SSTs also vary out of phase with millennial-scale changes in Northern Hemisphere temperature anomalies (NHTAs) and show relatively warm conditions during the Little Ice Age and relatively cool conditions during the Medieval Warm Period. Together, these results suggest that coastal upwelling varies with NHTAs and that upwelling off northwest Africa may continue to intensify as global warming and atmospheric CO2 levels increase.

1 DFG Research Center Ocean Margins, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.
2 Alfred Wegener Institute for Polar and Marine Research, Bussestrasse 24 (Building F), D-27570 Bremerhaven, Germany.
3 University of Bucharest, Faculty of Physics, Magurele 077125, Bucharest, Romania.
4 Institute of Environmental Physics, University of Bremen, Otto-Hahn-Allee 1, D-28359 Bremen, Germany.
5 MARUM Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany.

* Present addresses: Australian Nuclear Science and Technology Organisation, PMB1, Menai, NSW 2234, Australia, and School of Earth and Environmental Sciences, University of Wollongong, NSW 2522, Australia.

{dagger} To whom correspondence should be addressed. E-mail: mcgregor{at}uni-bremen.de

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