On the glacial-interglacial variability of the Asian monsoon in speleothem δ18O records

• Main Authors: Liu, Guangxin, Li, X., Chiang, Hong-Wei, Cheng, H., Yuan, S., Chawchai, S., He, S., Lu, Yanbin, Aung, Lin Thu, Maung, P. M., Tun, W. N., Oo, K. M., Wang, Xianfeng
• Other Authors: Asian School of the Environment
• Format: Article
• Language: English
• Published: 2020
• Subjects: Engineering::Environmental engineering; Monsoon; Speleothem
• Online Access: https://hdl.handle.net/10356/143905
• Institution: Nanyang Technological University

While Asian monsoon (AM) changes have been clearly captured in Chinese speleothem oxygen isotope (δ18O) records, the lack of glacial-interglacial variability in the records remains puzzling. Here, we report speleothem δ18O records from three locations along the trajectory of the Indian summer monsoon (ISM), a major branch of the AM, and characterize AM rainfall over the past 180,000 years. We have found that the records close to the monsoon moisture source show large glacial-interglacial variability, which then decreases landward. These changes likely reflect a stronger oxygen isotope fractionation associated with progressive rainout of AM moisture during glacial periods, possibly due to a larger temperature gradient and suppressed plant transpiration. We term this effect, which counteracts the forcing of glacial boundary conditions, the moisture transport pathway effect.