Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
Clim. Past, 7, 41-46, 2011
https://doi.org/10.5194/cp-7-41-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
12 Jan 2011
Early last glacial maximum in the southern Central Andes reveals northward shift of the westerlies at ~39 ka
R. Zech1,*, J. Zech1, Ch. Kull1, P. W. Kubik2, and H. Veit1 1Geographical Institute, University of Bern, Bern, Switzerland
2Ion Beam Physics, ETH Zurich, Zurich, Switzerland
*now at: Geological Institute, ETH Zurich, Switzerland
Abstract. The latitudinal position of the southern westerlies has been suggested to be a key parameter for the climate on Earth. According to the general notion, the southern westerlies were shifted equatorward during the global Last Glacial Maximum (LGM: ~24–18 ka), resulting in reduced deep ocean ventilation, accumulation of old dissolved carbon, and low atmospheric CO2 concentrations. In order to test this notion, we applied surface exposure dating on moraines in the southern Central Andes, where glacial mass balances are particularly sensitive to changes in precipitation, i.e. to the latitudinal position of the westerlies. Our results provide robust evidence that the maximum glaciation occurred already at ~39 ka, significantly predating the global LGM. This questions the role of the westerlies for atmospheric CO2, and it highlights our limited understanding of the forcings of atmospheric circulation.

Citation: Zech, R., Zech, J., Kull, Ch., Kubik, P. W., and Veit, H.: Early last glacial maximum in the southern Central Andes reveals northward shift of the westerlies at ~39 ka, Clim. Past, 7, 41-46, https://doi.org/10.5194/cp-7-41-2011, 2011.
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