Variability of PDO identified by a last 300-year stalagmite delta O-18 record in Southwest China

Stalagmite oxygen isotope (delta O-18) record has been widely used in characterizing Asian Monsoon variations. In southwest (SW) China, although the stalagmite delta O-18 was usually suggested as a precipitation proxy, it remains a subject of debate. Here we present two replicated, high-precise-dated stalagmite delta O-18 records for the interval 1710-2003 AD from Yunnan province, SW China. The stalagmite delta O-18 shows no correlation with the local monsoon precipitation, but a significantly positive correlation with the Pacific Decadal Oscillation (PDO) index. It demonstrates that the stalagmite delta O-18 in SW China is most likely influenced by the atmospheric circulation associated with the PDO through the upstream depletion mechanism. During the warm (cold) PDO period, the deficit rainfall over India would make the delta O-18 of water vapor transporting to SW China less (more) negative due to the weaker Rayleigh distillation process, which would lead to the less (more) negative stalagmite delta O-18. Consequently, the stalagmite delta O-18 in SW China is suitable to reconstruct the PDO variations. It is important to note that the other factors, such as El Nino-Southern Oscillation (ENSO) or sea surface temperature (SST) also possibly affect the stalagmite delta O-18 in SW China, and the relationship between them requires further studies. (C) 2021 Elsevier Ltd. All rights reserved