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Science 2 May 1986:
Vol. 232. no. 4750, pp. 619 - 622
DOI: 10.1126/science.232.4750.619
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Articles

A Mid-Brunhes Climatic Event: Long-Term Changes in Global Atmosphere and Ocean Circulation

J. H. F. JANSEN 1, A. KUIJPERS 2, and S. R. TROELSTRA 3

1 Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands.
2 Geological Survey of The Netherlands, P.O. Box 157, 2000 AD Haarlem, The Netherlands.
3 Institute of Earth Sciences of the Free University of Amsterdam, P.O. Box 7161, 1007 MC Amsterdam, The Netherlands.

A long-term climatic change 4.0 x 105 to 3.0 x 105 years ago is recorded in deep-sea sediments of the Angola and Canary basins in the eastern Atlantic Ocean. In the Angola Basin (Southern Hemisphere) the climatic signal shows a transition to more humid ("interglacial") conditions in equatorial Africa, and in the Canary Basin (Northern Hemisphere) to more "glacial" oceanic conditions. This trend is confirmed by comparison with all well-documented marine and continental records from various latitudes available; in the Northern Hemisphere, in the Atlantic north of 20°N, climate merged into more "glacial" conditions and in equatorial regions and in the Southern Hemisphere to more "interglacial" conditions. The data point to a more northern position of early Brunhes oceanic fronts and to an intensified atmosphere and ocean surface circulation in the Southern Hemisphere during that time, probably accompanied by a more zonal circulation in the Northern Hemisphere. The mid-Brunhes climatic change may have been forced by the orbital eccentricity cycle of 4.13 x 105 years.

Submitted on September 13, 1985
Accepted on January 29, 1986


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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