Multi-proxy validation of glacial-interglacial rainfall variations in southwest Sulawesi
Journal
Communications Earth and Environment
Journal Volume
4
Journal Issue
1
Date Issued
2023-12-01
Author(s)
Kimbrough, Alena K.
Gagan, Michael K.
Dunbar, Gavin B.
Hantoro, Wahyoe S.
Hu, Hsun Ming
Cheng, Hai
Edwards, R. Lawrence
Rifai, Hamdi
Suwargadi, Bambang W.
Abstract
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.
Type
journal article