Is Chinese stalagmite δ18O solely controlled by the Indian summer monsoon?

Abstract

As a unique continental archive, speleothem has been widely used in reconstructing paleoclimate change. However, the interpretation of Chinese speleothems δ18O has remained a subject of debate. Recently, a Community Atmosphere Model version 3 (CAM3) study indicated that the stalagmite δ18O from eastern China reflected the Indian summer monsoon (ISM) intensity rather than the East Asian summer monsoon (EASM) intensity during Heinrich events. Here, we present a high-resolution speleothem δ18O record from Xianglong Cave in Shaanxi province, China, covering the period of 25.5–10.9 ka BP. The XL15 record shows similar variations with ice core record from Greenland and other climate records from China and India on millennial scale, including Heinrich 2 (H2), Heinrich 1 (H1), Bolling–Allerod (BA) and Younger Dryas (YD) events, supporting the connection between the Asian monsoon and northern high latitude climate. The δ18O amplitude of our record is larger than or similar to the stalagmite δ18O records from India during these events. In addition, differences of stalagmite δ18O in eastern China and the ISM region were observed on glacial-interglacial as well as decadal timescales. That means the ISM is not the sole controlling factor of Chinese stalagmite δ18O during Heinrich events. When subtracting the Indian stalagmite δ18O series from our XL15 record during H1 period, we found a significant negative correlation with sea surface temperature (SST) record of Western Pacific Warm Pool (WPWP). Consequently, our study suggests that the Chinese stalagmite δ18O is controlled by both the ISM and EASM on orbital-, millennial-, and decadal timescales.