Paleoclimate Significance of Reconstructed Rainfall Isotope Changes in Asian Monsoon Region. Issue 12 (12th June 2021)

• Record Type: Journal Article
• Authors: Zhao, Cheng; Cheng, Jun; Wang, Jingjing; Yan, Hong; Leng, Chengcheng; Zhang, Can; Feng, Xiaoping; Liu, Weiguo; Yang, Xiangdong; Shen, Ji
• Is Part Of: Geophysical research letters. Volume 48:Issue 12(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-12
• Subjects: Asian monsoon -- lake sediments -- leaf wax hydrogen isotopes -- monsoon trough -- speleothems -- TraCE21ka simulation; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL092460
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Speleothem oxygen isotope (δ 18 Oc) records have been regarded as a critical reference to study past Asian monsoon variability. However, existing δ 18 Oc records in the Indian monsoon region are fragmented in time coverage and/or sampling resolution since the last deglaciation. Also, the climatic interpretation of δ 18 Oc is still obscure. Here, we report a continuous and centennial‐resolved leaf wax hydrogen isotope (δDwax ) record over the past ∼28 ka from Lugu Lake in Indian‐monsoon influenced southwestern China. Our new record shows striking consistency with the well‐established δ 18 Oc record in East Asian monsoon‐influenced southeastern China, revealing a spatially coherent change and thus a similar physical process in rainfall isotopes in the broader Asian monsoon region. Based on the combination with the TraCE21ka simulation, we propose reconstructed long‐term and millennial‐scale isotope changes could be influenced by the intensity of local convection along the monsoon trough, which extends from the Indian subcontinent across to the Philippines in summer. Plain Language Summary: Stable isotope records inferred from cave deposits have been widely regarded as a critical reference to investigate past Asian monsoon changes. In the Indian monsoon region, however, available cave records often have gaps in time coverage. Also, the physical interpretation of these isotope records is still obscure. In this study, we derive a continuous and centennial‐resolved leaf wax hydrogen isotope record over the past ∼28 ka from a lake in Indian‐monsoon influenced southwestern China. The new record shows consistent variations with the well‐established speleothem record in East Asian monsoon‐influenced southeastern China, indicating spatially consistent variability across the Indian and East‐Asian regions. By examining the TraCE21ka climate model simulation, we find isotope changes in the Asian monsoon region might be connected with the strength of the monsoon trough. Key Points: A continuous and centennial‐resolved leaf wax hydrogen isotope record (δDwax ) over the past 28 ka in Indian‐monsoon influenced southwestern China Consistent long‐term and millennial variations in reconstructed rainfall isotopes in Indian and East Asian monsoon regions A possible link between reconstructed rainfall isotopes and the monsoon trough revealed by TraCE21ka transient simulation