Holocene climate forcings on leaf wax hydrogen isotope records in the monsoon regions of China

<p>The hydrogen isotopic compositions (δD) of leaf waxes have emerged as a pivotal paleohydrological proxy. However, their complex nature complicates paleoclimatic interpretations in the monsoon regions of China. To disentangle the controls, we performed principal component analysis (PCA) on Holocene leaf wax δD records from peat deposits across the monsoon regions of China, which reveals three dominant signals. The first principal component (PC1) strongly correlates with water vapor source isotopes. The second principal component (PC2) shows a close relationship with El Niño-Southern Oscillation (ENSO) mean state. The third principal component (PC3) is associated with North Atlantic cooling. Together, PC2 and PC3 mainly account for the spatiotemporal variations of precipitation in the monsoon regions of China. The PCA results highlight that while Northern hemisphere solar insolation provides the fundamental control, both high- and low-latitude climate systems modulate the isotopic signals. Moreover, these findings offer new insights into resolving the discrepancies between leaf wax δD and stalagmite δ<sup>18</sup>O records in the Asian monsoon regions during the Holocene. Given the observed covariation between PC1 and stalagmite δ<sup>18</sup>O records, we tentatively attribute the differences to moisture-dependent biological factors significantly affecting leaf wax δD.</p>