Scroxton, Nick and Gagan, Michael K. and Ayliffe, Linda K. and Hantoro, Wahyoe S. and Hellstrom, John C. and Cheng, Hai and Edwards, R. Lawrence and Zhao, Jian-xin and Suwargadi, Bambang W. and Rifai, Hamdi (2022) Antiphase response of the Indonesian–Australian monsoon to millennial-scale events of the last glacial period. Scientific Reports, 12 (1). ISSN 2045-2322

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Abstract

Antiphase behaviour of monsoon systems in alternate hemispheres is well established at yearly and orbital scales in response to alternating sensible heating of continental landmasses. At intermediate timescales without a sensible heating mechanism both in-phase and antiphase behaviours of northern and southern hemisphere monsoon systems are recorded at different places and timescales. At present, there is no continuous, high resolution, precisely dated record of millennial-scale variability of the Indonesian–Australian monsoon during the last glacial period with which to test theories of paleomonsoon behaviour. Here, we present an extension of the Liang Luar, Flores, speleothem δ18O record of past changes in southern hemisphere summer monsoon intensity back to 55.7 kyr BP. Negative δ18O excursions (stronger monsoon) occur during Heinrich events whereas positive excursions (weaker monsoon) occur during Dansgaard-Oeschger interstadials—a first order antiphase relationship with northern hemisphere summer monsoon records. An association of negative δ18O excursions with speleothem growth phases in Liang Luar suggests that these stronger monsoons are related to higher rainfall amounts. However, the response to millennial-scale variability is inconsistent, including a particularly weak response to Heinrich event 3. We suggest that additional drivers such as underlying orbital-scale variability and drip hydrology influence the δ18O response.

Item Type:	Article
Additional Information:	Fieldwork in Indonesia was carried out in collaboration with the Indonesian Institute of Sciences (LIPI) under LIPI research permit numbers 04057/SU/KS/2006 and 2748/SU.3/KS/2007, and Kementerian Negara Riset dan Teknologi (RISTEK) research permit numbers 04/TKPIPA/FRP/SM/IV/2009 and 1b/TKPIPA/FRP/SM/I/2011. We are grateful to the people of Rampasasa village for their generous support in the field and to Neil Anderson, Garry Smith, Russell Drysdale, Jodie Rutledge, Dan Zwartz, Eko Yulianto, Michael Griffiths, Sophie Lewis, Emma St Pierre, Julie Mazerat, Engkos Kosasih and Djupriono who provided invaluable caving expertise and technical support. We also thank Joe Cali, Heather Scott-Gagan, and Joan Cowley for outstanding laboratory assistance. The authors would like to thank Frank McDermott for his feedback on an early draft.
Keywords:	Antiphase response; Indonesian–Australian monsoon; millennial-scale events; glacial period;
Academic Unit:	Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS
Item ID:	17529
Identification Number:	https://doi.org/10.1038/s41598-022-21843-8
Depositing User:	Nick Scroxton
Date Deposited:	11 Sep 2023 13:43
Journal or Publication Title:	Scientific Reports
Publisher:	Nature Publishing Group
Refereed:	Yes
Funders:	This work was supported by Australian Research Council (ARC) Discovery Project grants DP0663274, DP1095673 and DP180103762 to MKG, WSH, J-xZ, JCH, RLE and HC; U.S. NSF grants 1103402, 1702816 and 2202913 to RLE. and HC;, and National Natural Science Foundation of China grants NSFC 41731174 and 41888101 to HC
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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