Decadal-to Century-scale High Resolution Stalagmites Record Of Asian Monsoon During The Last Interglacial

The last interglacial period has been considered to be an analogue to the present interglacial period, the Holocene, which may help us to understand present climate evolution. ²³⁰Th ages and oxygen isotope data of five stalagmites from Shanbao, Yongxing Cave in Hubei Province and hulu cave in Jiangsu Province characterize the East Asian Monsoon precipitation from 140 tol 10 kaBP. The record broadly follows 33° summer insolation. Similar changing trend was observed in the two δ¹⁸O curves derived from the Shanbao Cave and Dongge Cave, which proved the changes of the oxygen composition of the Asian Monsoon precipitation have the generally regional meanings.The decadal-scale high-resolution δ¹⁸O record reveals a detailed transitional process from the Penultimate glaciation to the Last Interglaciation. As established with ²³⁰Th dates, the age of the Termination II is determined to be 129.5±1.0kaBP, which supports the Northern Hemisphere insolation as the triggers for the ice-age cycles. In our δ¹⁸O record, the glacial/interglacial fluctuation reaches about 4‰, almost the same level in other Asian monsoon cave stalagmite δ¹⁸O records. The transition of the glacial/interglacial period in our record can be recognized four stepwise stages, among which, a rapid rise of Monsoon precipitation follows the stage of "Termination II pause". The rapid rise is synchronous with the abrupt change of global methane concentration, which reflects that an increase in both Asian monsoon precipitation and tropical wetland play an important role in the global climate changes.During the Last Interglacial period, average decadal-scale δ¹⁸O record shows high frequency fluctuation. This period is characterized by decadal- to century-scale oscillations in oxygen isotope records, where both the absolute values and the isotope ranges are similar to Holocene from the same Asian mosoon region. Power spectral analysis of the record shows statistically significant centennial periodicities centered on 525, 285, 228, 207, 157, 121-126, 60å’Œ19²3a. These periodicities are close to significant periods of the Δ¹⁴C record, indicates that solar changes are also responsible for changes of Asian Monsoon intensity.