Paleoclimate Significance of Reconstructed Rainfall Isotope Changes in Asian Monsoon Region

Abstract

Speleothem oxygen isotope (δ18Oc) records have been regarded as a critical reference to study past Asian monsoon variability. However, existing δ18Oc records in the Indian monsoon region are fragmented in time coverage and/or sampling resolution since the last deglaciation. Also, the climatic interpretation of δ18Oc 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 δ18Oc 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.

Asynchronous variations of East Asian summer monsoon, vegetation and soil formation at Yulin (North China) in the Holocene

“…It is possible that a position of the rainfall belt further north under a stronger monsoon would lead to less precipitation in the middle and lower reaches of the Yangtze River; precipitation there would be positively correlated with the heavy isotope (Rao et al , 2016; Zhang et al , 2018; Liu et al , 2020). Overall, δD p indicates the large‐scale intensity of EASM, and especially in northern China, δD p can indicate local rainfall amount (Tan et al , 2020; Zhang et al , 2021; Zhao et al , 2021). Nevertheless, based on the aforementioned evidence and the result of climate simulations (Liu et al , 2014; He et al , 2021), as our study site Yulin is located at the margin of the EASM with precipitation mainly occurring in boreal summer (Fig.…”

“…The intensity of the EASM is reflected in the large-scale circulation and concomitant latitudinal shifts of the monsoon frontal rainfall belt (Jiang et al, 2008;Ding et al, 2018). When the monsoon is strong, the water vapour could also have a remote source with a more intense rainout process and finally induce more depleted isotope values (Cheng et al, 2016(Cheng et al, , 2019(Cheng et al, , 2021Zhang et al, 2019Zhang et al, , 2020Zhao et al, 2021;Liu et al, 2020). As a result of this up-stream depletion effect, lower δD p of the EASM region is interpreted as a stronger monsoon, while higher δD p represents a weaker monsoon (Liu et al, 2020).…”

“…Long‐chain n ‐alkanes, compounds that make up leaf waxes in higher plants, have been used as the biomarker for palaeoclimate and palaeoenvironment studies because of their chemical inertness and resistance to biodegradation, and sensibility to vegetation and environmental changes (Eglinton and Eglinton, 2008; Eglinton and Hamilton, 1967; Zhang et al , 2006). To date, they have been widely used in studies of marine sediments (Tierney and DeMenocal, 2013), lake sediments (Aichner et al , 2015; Hou et al , 2018; Rao et al , 2016; Zhao et al , 2021), peat (Huang et al , 2018; Huang and Meyers, 2019) and loess (Xie et al , 2003; Zhang et al , 2006; Wang et al , 2018, 2021). With increasing aridity, plants will have a higher productivity for leaf wax, thus the concentration of soil n ‐alkanes might be used as a proxy for climatic aridity (Hoffmann et al , 2013; Ni et al , 2015; Srivastava and Wiesenberg, 2018).…”

Fire History in the Qinling Mountains of East‐Central China Since the Last Glacial Maximum

“…In order to obtain the reliable chronological sequence through the late glacial, leaf wax hydrogen isotopes (δD wax ) in Daye Lake (Text S1.1 in Supporting Information S1) were compared with the adjacent stalagmite oxygen isotopes (δ 18 O s ) records from Haozhu Cave (Zhang et al, 2018). The match of the two precipitation signals was carried out by using the QAnalySeries software (Kotov and Pälike, 2018;Zhao et al, 2021). The detailed information can be seen in Text S2 in Supporting Information S1.…”

Quantitative temperature and relative humidity changes recorded by the Lake Cuoqia in the southeastern Tibetan Plateau during the past 300 years

“…(Dansgaard, 1964;Cai et al, 2012;Sachse et al, 2012;Zhang et al, 2020). The water required for plants in the lake catchment mainly derived from soil water which is influenced by monsoon precipitation and soil evaporation effect (Sachse et al, 2004(Sachse et al, , 2012Zhao et al, 2021b). Thus, leaf wax δD should mainly reflect the variations in the relative humidity.…”