Claire E. Krause, Alena K. Kimbrough, Michael K. Gagan, Peter O. Hopcroft, Gavin B. Dunbar, Wahyoe S. Hantoro, John C. Hellstrom, Hai Cheng, R. Lawrence Edwards, Henri Wong, Bambang W. Suwargadi, Paul J. Valdes, Hamdi Rifai
Recent research has shown the potential of speleothem δ13C to record a range of environmental processes. Here, we report on 230Th-dated stalagmite δ13C records for southwest Sulawesi, Indonesia, over the last 40,000 yr to investigate the relationship between tropical vegetation productivity and atmospheric methane concentrations. We demonstrate that the Sulawesi stalagmite δ13C record is driven by changes in vegetation productivity and soil respiration and explore the link between soil respiration and tropical methane emissions using HadCM3 and the Sheffield Dynamic Global Vegetation Model. The model indicates that changes in soil respiration are primarily driven by changes in temperature and CO2, in line with our interpretation of stalagmite δ13C. In turn, modelled methane emissions are driven by soil respiration, providing a mechanism that links methane to stalagmite δ13C. This relationship is particularly strong during the last glaciation, indicating a key role for the tropics in controlling atmospheric methane when emissions from high-latitude boreal wetlands were suppressed. With further investigation, the link between δ13C in stalagmites and tropical methane could provide a low-latitude proxy complementary to polar ice core records to improve our understanding of the glacial–interglacial methane budget. © 2024 Cambridge University Press. All rights reserved.
Research School of Earth Sciences, Australian National University, Canberra, 2601, ACT, Australia; School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, 2522, NSW, Australia; School of Earth and Environmental Sciences, University of Queensland, St. Lucia, 4072, QLD, Australia; School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom; Antarctic Research Centre, Victoria University of Wellington, Wellington, 6140, New Zealand; Research Center for Geotechnology, Indonesian Institute of Sciences, Bandung, 40135, Indonesia; School of Earth Sciences, University of Melbourne, Parkville, 3010, VIC, Australia; Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an, 710049, China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, 710061, China; Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, 55455, MN, United States; Australian Nuclear Science and Technology Organisation, Lucas Heights, 2234, NSW, Australia; School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, United Kingdom; Department of Physics, Universitas Negeri Padang, Padang, 25131, Indonesia; Geoscience Australia, Symonston, 2609, ACT, Australia
