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Indo-Pacific Walker circulation drove Pleistocene African aridification

van der Lubbe, H. J. L., Hall, I. R. ORCID:, Barker, S. ORCID:, Hemming, S. R., Baars, T. F., Starr, A., Just, J., Backeberg, B. C. and Joordens, J. C. A. 2021. Indo-Pacific Walker circulation drove Pleistocene African aridification. Nature 598 (7882) , pp. 618-623. 10.1038/s41586-021-03896-3

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Today, the eastern African hydroclimate is tightly linked to fluctuations in the zonal atmospheric Walker circulation1,2. A growing body of evidence indicates that this circulation shaped hydroclimatic conditions in the Indian Ocean region also on much longer, glacial–interglacial timescales3,4,5, following the development of Pacific Walker circulation around 2.2–2.0 million years ago (Ma)6,7. However, continuous long-term records to determine the timing and mechanisms of Pacific-influenced climate transitions in the Indian Ocean have been unavailable. Here we present a seven-million-year-long record of wind-driven circulation of the tropical Indian Ocean, as recorded in Mozambique Channel Throughflow (MCT) flow-speed variations. We show that the MCT flow speed was relatively weak and steady until 2.1 ± 0.1 Ma, when it began to increase, coincident with the intensification of the Pacific Walker circulation6,7. Strong increases during glacial periods, which reached maxima after the Mid-Pleistocene Transition (0.9–0.64 Ma; ref. 8), were punctuated by weak flow speeds during interglacial periods. We provide a mechanism explaining that increasing MCT flow speeds reflect synchronous development of the Indo-Pacific Walker cells that promote aridification in Africa. Our results suggest that after about 2.1 Ma, the increasing aridification is punctuated by pronounced humid interglacial periods. This record will facilitate testing of hypotheses of climate–environmental drivers for hominin evolution and dispersal.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Environmental Sciences
Publisher: Nature Research
ISSN: 0028-0836
Funders: NERC
Date of First Compliant Deposit: 10 November 2021
Date of Acceptance: 11 September 2021
Last Modified: 09 Nov 2023 10:41

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