Biomarker reconstructions of temperature and hydroclimate variability in Vietnam during Marine Isotope Stage 3

• Published in: Quaternary science reviews Vol. 341; p. 108893
• Main Authors: Tran, Trang T., Stevens, Lora, Tierney, Jessica E., Vu-Van, Tich
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2024
• Subjects: Leaf wax; MIS 3; Paleoclimate; SE Asia; Tropical soil biomarkers; Paleoclimate; MIS 3; SE Asia; Leaf wax; Tropical soil biomarkers
• ISSN: 0277-3791
• DOI: 10.1016/j.quascirev.2024.108893

Limited hydrological data coupled with a reliance on the monsoon rains for agriculture make Southeast (SE) Asia vulnerable to climate change. To develop a better understanding of how SE Asia responds to climatic forcings, we provide a paleoclimate perspective by reconstructing temperature and hydroclimate from a wetland outcrop in the Central Highlands of Vietnam (CHV) during Marine Isotope Stage 3 (MIS 3). Mean annual atmospheric temperatures inferred from brGDGTs (branched glycerol dialkyl glycerol tetraethers) indicate an increase from 23 to 26 °C between ∼54 and 37 cal ka BP, which follows an increase in mean annual insolation at the latitude of the site. δDwax data show a shift from a greater proportion of summer monsoon rain derived from the Bay of Bengal between 54 and 49 cal ka BP toward more autumn rain from the South China Sea (also known as the Vietnam East Sea) for most of the rest of the record. brGDGT-inferred soil pH suggests that the climate was wetter at 54 to 49 cal ka BP, then became drier, then returned to wet conditions approaching 37 cal ka BP. Both orbital forcing and changes in the exposure of the Sunda Shelf likely influenced hydroclimate in the CHV. δ13Cwax indicates that C4 plants dominate the vegetation cover during MIS 3. Comparison between our new record from the CHV with existing water isotope proxy records reveals coherent changes with nearby speleothem data, but regional differences between the history of hydroclimate in SE Asia and in the central Indian Monsoon domain. As a snapshot of glacial climate conditions, our data provide new information on the past drivers of climate in an understudied region. •MIS 3 temperatures in Central Highlands Vietnam were as warm as today and increase at the end of record.•CHV hydroclimate was dominated by summer monsoon rain at the start of MIS 3, then switched to more autumn rain.•Vegetation cover during MIS 3 mostly consisted of C4 plants.•Variations in hydroclimate were driven by orbital forcing and changing exposure of the Sunda shelf.