Alena K. Kimbrough, Michael K. Gagan, Gavin B. Dunbar, Wahyoe S. Hantoro, Chuan-Chou Shen, Hsun-Ming Hu, Hai Cheng, R. Lawrence Edwards, Hamdi Rifai, Bambang W. Suwargadi
Speleothem δ18O is widely used as a proxy for rainfall amount in the tropics on glacial-interglacial to interannual scales. However, uncertainties in the interpretation of this renowned proxy pose a vexing problem in tropical paleoclimatology. Here, we present paired multi-proxy geochemical measurements for stalagmites from southwest Sulawesi, Indonesia, and confirm changes in rainfall amount across ice age terminations. Collectively, the stalagmites span two glacial-interglacial transitions from ~380,000 to 330,000 and 230,000 to 170,000 years ago. Mg/Ca in the slow-growing stalagmites is affected by water moving through the karst and prior calcite precipitation, making it a good proxy for changes in local rainfall. When paired, Mg/Ca and δ18O corroborate prominent shifts from drier glacials to wetter interglacials in the core of the Australasian monsoon domain. These shifts in rainfall occur 4,000-7,000 years later than glacial-interglacial increases in global temperature and the associated response of Sulawesi vegetation, determined by speleothem δ13C. © 2023, The Author(s).
Research School of Earth Sciences, The Australian National University, Acton, 2601, ACT, Australia; School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, 2522, NSW, Australia; School of Earth and Environmental Sciences, The University of Queensland, St. Lucia, 4072, QLD, Australia; Antarctic Research Centre, Victoria University of Wellington, Wellington, 6140, New Zealand; Research Center for Geotechnology, Indonesian Institute of Sciences, Bandung, 40135, Indonesia; High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei, 10617, Taiwan; Research Center for Future Earth, National Taiwan University, Taipei, 10617, Taiwan; Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an, 710054, China; Key Laboratory of Karst Dynamics, MLR, Institute of Karst Geology, CAGS, Guilin, 541004, China; Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, 55455, MN, United States; Department of Physics, Universitas Negeri Padang, Padang, 25131, Indonesia
