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

G Liu; X Li; H-W Chiang; H Cheng; S Yuan; S Chawchai; S He; Y Lu; L T Aung; P M Maung; W N Tun; K M Oo; X Wang

doi:10.1126/sciadv.aay8189

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

Sci Adv. 2020 Feb 12;6(7):eaay8189. doi: 10.1126/sciadv.aay8189. eCollection 2020 Feb.

Authors

G Liu^{1

2

3}, X Li⁴, H-W Chiang², H Cheng⁴, S Yuan^{1

2

3}, S Chawchai⁵, S He², Y Lu², L T Aung^{2

6}, P M Maung^{2

7}, W N Tun⁶, K M Oo⁷, X Wang^{2

3}

Affiliations

¹ Interdisciplinary Graduate School, Nanyang Technological University, 639798 Singapore.
² Earth Observatory of Singapore, Nanyang Technological University, 639798 Singapore.
³ Asian School of the Environment, Nanyang Technological University, 639798 Singapore.
⁴ Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an 710049, China.
⁵ Department of Geology, Chulalongkorn University, Bangkok 10330, Thailand.
⁶ Myanmar Earthquake Committee, Yangon 11052, Myanmar.
⁷ Department of Meteorology and Hydrology, Nay Pyi Taw 15011, Myanmar.

Abstract

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.

Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).