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Precipitation variability in the winter rainfall zone of South Africa during the last 1400 yr linked to the austral westerlies

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Author(s): J. C. Stager | P. A. Mayewski | J. White | B. M. Chase | F. H. Neumann | M. E. Meadows | C. D. King | D. A. Dixon

Journal: Climate of the Past Discussions
ISSN 1814-9340

Volume: 7;
Issue: 6;
Start page: 4375;
Date: 2011;
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ABSTRACT
The austral westerlies strongly influence precipitation and ocean circulation in the southern temperate zone, with important consequences for cultures and ecosystems. Global climate models anticipate poleward contraction of the austral westerlies with future warming, but the available paleoclimate records that might test these models have been largely limited to South America, are not fully consistent with each other, and may be complicated by influences from other climatic factors. Here we present the first fine-interval diatom and sedimentological records from the winter rainfall region of South Africa, representing precipitation during the last 1400 yr. Inferred rainfall increased ~1400–1200 cal yr BP and most notably during the Little Ice Age with pulses centered on ~600, 530, 470, 330, 200, and 90 cal yr BP. Synchronous fluctuations in Antarctic ice core chemistry strongly suggest that these variations are linked to changes in the westerlies. Partial inconsistencies among South African and South American records warn against the simplistic application of local-scale histories to the Southern Hemisphere as a whole. Nonetheless, these findings in general do support model projections of increasing aridity in austral winter rainfall zones with future warming.
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