Paleoclimate Significance of Reconstructed Rainfall Isotope Changes in Asian Monsoon Region

Speleothem oxygen isotope (delta(18)Oc) records have been regarded as a critical reference to study past Asian monsoon variability. However, existing delta(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 delta(18)Oc is still obscure. Here, we report a continuous and centennial-resolved leaf wax hydrogen isotope (delta D-wax) record over the past similar to 28 ka from Lugu Lake in Indian-monsoon influenced southwestern China. Our new record shows striking consistency with the well-established delta(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