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Science 14 May 1999:
Vol. 284. no. 5417, pp. 1150 - 1152
DOI: 10.1126/science.284.5417.1150
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Reports

65,000 Years of Vegetation Change in Central Australia and the Australian Summer Monsoon

B. J. Johnson, 12*dagger G. H. Miller, 2 M. L. Fogel, 1 J. W. Magee, 3 M. K. Gagan, 4 A. R. Chivas 5

Carbon isotopes in fossil emu (Dromaius novaehollandiae) eggshell from Lake Eyre, South Australia, demonstrate that the relative abundance of C4 grasses varied substantially during the past 65,000 years. Currently, C4 grasses are more abundant in regions that are increasingly affected by warm-season precipitation. Thus, an expansion of C4 grasses likely reflects an increase in the relative effectiveness of the Australian summer monsoon, which controls summer precipitation over Lake Eyre. The data imply that the Australian monsoon was most effective between 45,000 and 65,000 years ago, least effective during the Last Glacial Maximum, and moderately effective during the Holocene.

1 Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015-1305, USA.
2 Institute of Arctic and Alpine Research and Department of Geological Sciences, University of Colorado, Boulder, CO 80309-0450, USA.
3 Department of Geology,
4 Research School of Earth Sciences, Australian National University, Canberra ACT 0200, Australia.
5 School of Geosciences, University of Wollongong, Wollongong NSW 2522, Australia.
*   Present address: School of Oceanography, University of Washington, Seattle, WA 98195-7940, USA.

dagger    To whom correspondence should be addressed. E-mail: bjohnson{at}ocean.washington.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Carbon isotope evidence for an abrupt reduction in grasses coincident with European settlement of Lake Eyre, South Australia.
B. J. Johnson, G. H. Miller, J. W. Magee, M. K. Gagan, M. L. Fogel, and P. D. Quay (2005)
The Holocene 15, 888-896
   Abstract »    PDF »
Multiple expansions of C4 plant biomass in East Asia since 7 Ma coupled with strengthened monsoon circulation.
A. Zhisheng, H. Yongsong, L. Weiguo, G. Zhengtang, S. Clemens, L. Li, W. Prell, N. Youfeng, C. Yanjun, Z. Weijian, et al. (2005)
Geology 33, 705-708
   Abstract »    Full Text »    PDF »
Ecosystem Collapse in Pleistocene Australia and a Human Role in Megafaunal Extinction.
G. H. Miller, M. L. Fogel, J. W. Magee, M. K. Gagan, S. J. Clarke, and B. J. Johnson (2005)
Science 309, 287-290
   Abstract »    Full Text »    PDF »
Continuous 150 k.y. monsoon record from Lake Eyre, Australia: Insolation-forcing implications and unexpected Holocene failure.
J. W. Magee, G. H. Miller, N. A. Spooner, and D. Questiaux (2004)
Geology 32, 885-888
   Abstract »    Full Text »    PDF »
New Ages for the Last Australian Megafauna: Continent-Wide Extinction About 46,000 Years Ago.
R. G. Roberts, T. F. Flannery, L. K. Ayliffe, H. Yoshida, J. M. Olley, G. J. Prideaux, G. M. Laslett, A. Baynes, M. A. Smith, R. Jones, et al. (2001)
Science 292, 1888-1892
   Abstract »    Full Text »    PDF »


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