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Glacial to Holocene swings of the Australian–Indonesian monsoon

2011; Nature Portfolio; Volume: 4; Issue: 8 Linguagem: Inglês

10.1038/ngeo1209

1752-0908

Mahyar Mohtadi, Delia W Oppo, Stephan Steinke, Jan-Berend W Stuut, Ricardo De Pol‐Holz, Dierk Hebbeln, Andreas Lückge,

Methane Hydrates and Related Phenomena

The Australian–Indonesian monsoon is an important component of the climate system in the tropical Indo-Pacific region. High-resolution records of monsoon-controlled austral winter upwelling during the past 22,000 years reveal that glacial–interglacial variations in the Australian–Indonesian winter monsoon have been in phase with the Indian summer monsoon system. The Australian–Indonesian monsoon is an important component of the climate system in the tropical Indo–Pacific region1. However, its past variability, relation with northern and southern high-latitude climate and connection to the other Asian monsoon systems are poorly understood. Here we present high-resolution records of monsoon-controlled austral winter upwelling during the past 22,000 years, based on planktic foraminiferal oxygen isotopes and faunal composition in a sedimentary archive collected offshore southern Java. We show that glacial–interglacial variations in the Australian–Indonesian winter monsoon were in phase with the Indian summer monsoon system, consistent with their modern linkage through cross-equatorial surface winds. Likewise, millennial-scale variability of upwelling shares similar sign and timing with upwelling variability in the Arabian Sea. On the basis of element composition and grain-size distribution as precipitation-sensitive proxies in the same archive, we infer that (austral) summer monsoon rainfall was highest during the Bølling–Allerød period and the past 2,500 years. Our results indicate drier conditions during Heinrich Stadial 1 due to a southward shift of summer rainfall and a relatively weak Hadley cell south of the Equator. We suggest that the Australian–Indonesian summer and winter monsoon variability were closely linked to summer insolation and abrupt climate changes in the northern hemisphere.