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Increasing Australian-Indonesian monsoon rainfall linked to early Holocene sea-level rise
Nature GeoScience
Vol. 2, No. 9, pp. 636-639, September 2009
doi:10.1038/ngeo605
M. L. Griffiths1, R. N. Drysdale1, M. K. Gagan2, J.-x. Zhao3,
L. K. Ayliffe2, J. C. Hellstrom4, W. S. Hantoro5, S. Frisia1,
Y.-x. Feng3, I. Cartwright6, E. St. Pierre3, M. J. Fischer7
and B.W. Suwargadi5
1Environmental and Climate Change Group, The University of Newcastle, Callaghan, New SouthWales 2308, Australia
2Research School of Earth Sciences, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
3Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland 4072, Australia
4School of Earth Sciences, The University of Melbourne, Parkville, Victoria 2010, Australia
5Research and Development Center for Geotechnology, Indonesian Institute of Sciences, Bandung, 40135, Indonesia
6School of Geosciences, Monash University, Clayton, Victoria 3800, Australia
7Australian Nuclear Science and Technology Organisation, PMB1, Menai, New South Wales 2234, Australia
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ABSTRACT:
The Australian-Indonesian summer monsoon affects rainfall variability
and hence terrestrial productivity in the densely populated tropical
Indo-Pacific region. It has been proposed that the main control of
summer monsoon precipitation on millennial timescales is local
insolation, but unravelling the mechanisms that have influenced
monsoon variability and teleconnections has proven difficult, owing
to the lack of high-resolution records of past monsoon behaviour.
Here we present a precisely dated reconstruction of monsoon rainfall
over the past 12,000 years, based on oxygen isotope measurements
from two stalagmites collected in southeast Indonesia. We show that
the summer monsoon precipitation increased during the Younger Dryas
cooling event, when Atlantic meridional overturning circulation was
relatively weak. Monsoon precipitation intensified even more rapidly
from 11,000 to 7,000 years ago, when the Indonesian continental shelf
was flooded by global sea-level rise. We suggest that the
intensification during the Younger Dryas cooling was caused by
enhanced winter monsoon outflow from Asia and a related southward
migration of the intertropical convergence zone. However, the early
Holocene intensification of monsoon precipitation was driven by
sea-level rise, which increased the supply of moisture to the
Indonesian archipelago.
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