Holocene climate variability in the winter rainfall zone of South Africa
-
Published:2013-10-22
Issue:5
Volume:9
Page:2347-2364
-
ISSN:1814-9332
-
Container-title:Climate of the Past
-
language:en
-
Short-container-title:Clim. Past
Author:
Weldeab S., Stuut J.-B. W.ORCID, Schneider R. R., Siebel W.
Abstract
Abstract. We established a multi-proxy time series comprising analyses of major elements in bulk sediments, Sr and Nd isotopes, grain size of terrigenous fraction, and δ18O and δ13C in tests of Neogloboquadrina pachyderma (sinistral) from a marine sediment sequence recovered off the Orange River. The records reveal coherent patterns of variability that reflect changes in wind strength, precipitation over the river catchments, and upwelling of cold and nutrient-rich coastal waters off western South Africa. The wettest episode of the Holocene in the winter rainfall zone (WRZ) of South Africa occurred during the "Little Ice Age" (700–100 cal years BP) most likely in response to a northward shift of the austral westerlies. Wet phases and strengthened coastal water upwellings are companied by a decrease of Agulhas water leakage into the South Atlantic and a reduced dust incursion over Antarctica, as indicated in previous studies. A continuous aridification trend in the WRZ and a weakening of the southern Benguela Upwelling System (BUS) between 9000 and 5500 cal years BP parallel with increase of dust deposition over Antarctica and an enhanced leakage of warm Agulhas water into the eastern South Atlantic. The temporal relationship between precipitation changes in the WRZ, the thermal state of the coastal surface water, and leakage of warm water in the South Atlantic, and variation of dust incursion over Antarctica suggests a causal link that most likely was related to latitudinal shifts of the Southern Hemisphere westerlies. Our results of the mid-Holocene time interval may serve as an analogue to a possible long-term consequence of the current and future southward shift of the westerlies. Furthermore, warming of the coastal surface water as a result of warm Agulhas water incursion into the southern BUS may affect coastal fog formation.
Publisher
Copernicus GmbH
Subject
Paleontology,Stratigraphy,Global and Planetary Change
Reference83 articles.
1. Bard, E., Hamelin, B., Arnold, M., Montaggioni, L., Cabioch, G., Faure, G., and Rougerie, F.: Deglacial sea-level record from Tahiti corals and the timing of global meltwater discharge, Nature, 382, 241–244, 1996. 2. Bayon, G., German, C. R., Nesbitt, R. W., Bertrand, P., and Schneider, R. R.: Increased input of circumpolar deep water-borne detritus to the glacial SE Atlantic Ocean, Geochem. Geophys. Geosys., 4, 1025, https://doi.org/1010.1029/2002GC000371, 2003. 3. Beal, L. M., De Ruijter, W. P. M., Biastoch, A., and Zahn, R.: On the role of the Agulhas system in ocean circulation and climate, Nature, 472, 429–436, 2011. 4. Bemis, B. E., Spero, H., Bijma, J., and Lea, D. W.: Reevaluation of oxygen isotope composition of planktonic foraminifera: experimental results and revised paleotemperature equations, Paleoceanography, 13, 150–160, 1998. 5. Benito, G., Thorndycraft, V. R., Rico, M. T., Sanchez-Moya, Y., Sopena, A., Botero, B. A., Machado, M. J., Davis, M., and Perez-Gonzalez, A.: Hydrological response of a dryland ephemeral river to southern African climatic variability during the last millennium, Quaternary Res., 75, 471–482, https://doi.org/10.1016/j.yqres.2011.01.004, 2011.
Cited by
44 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|