A 230Th/U-dated stalagmite from Hulu Cave was analyzed for δ18O, δ13C, and trace elements. A ~10-yr-resolution δ18O record, spanning 51.7–42.6 ka, revealed Dansgaard-Oeschger (DO) events 14 to 11. A similar rapid transition and synchronous timing of the onset of DO 12 is evident between the Greenland and Hulu Cave records, which suggests a common forcing mechanism of DO cycles in the North Atlantic and monsoonal region of Asia. Centennial-scale monsoonal oscillations in the cave δ18O record are indicative of hydroclimatic instability during interstadials. After removing the signals of remote moisture sources, the proportion of moisture from nearby sources is found to be higher during stadials than during interstadials. To explain this, we propose that the movement of the westerly jet is an important control on the balance of nearby and distant moisture sources in East Asia. In addition, the records of δ13C and trace element ratios, which are proxies of local environmental changes, resemble the δ18O record on the scale of DO cycles, as well as on even shorter timescales. This suggests that hydrological processes and biological activity at the cave site respond sensitively to the monsoonal changes.

A precisely 230Th-dated stalagmite δ13C profile from Hulu Cave, China, is presented to characterize the frequency and pattern of millennial-scale Asian monsoon (AM) variability from 160.6 to 132.5 ka. Evidence for an antiphased relationship of the δ13C and δ18O on the millennial scale suggests that the δ13C is indicative of the local hydrological cycle associated with changes in AM strength. Owing to the δ13C responding to AM changes more sensitively than the δ18O, we could identify 15 strong AM events that correlate to cold intervals recorded in Antarctic ice cores within 230Th dating uncertainty. This result supports a dynamic link of AM strength and southern hemispheric climates via the cross-equatorial airflows. Power spectrum analysis shows a predominant periodicity of 1.5–2.5 ka for the δ13C profile, similar to the Dansgaard-Oeschger frequency during the last glacial period. Moreover, the AM events are characterized by rapid transitions at the onset, suggesting that the observed millennial-scale AM variability is likely forced by northern high-latitude climates via north–south shifts of the Intertropical Convergence Zone associated with the bipolar seesaw mechanism. As evidence for a common mechanism for ice age terminations, a strong AM event (~134 ka) surrounding Termination II is analogous to the Bølling-Allerød warming interval.

A high-resolution, annual layer-counted and 230Th-dated multi-proxy record is constructed from a stalagmite in Hulu Cave, China. These proxies, including δ18O, annual layer thickness (ALT), gray level (GL) and Sr/Ca, cover a time span of ~ 3000 yr from 21 to 24 ka. The physical proxies (ALT and GL) and the geochemical index (Sr/Ca), all primarily reflecting karst hydrological processes, vary in concert and their coherence is supported by wavelet analyses. Variations in the δ18O data agree with fluctuations in the ALT and Sr/Ca records on multi-decadal to centennial scales, suggesting that the Hulu δ18O signal is strongly associated with varying local rainfall amounts on short timescales. A monsoon failure event at ~ 22.2 ka correlates with a decrease in tropical rainfall, a reduction in global CH 4 and an ice-rafted event in the North Atlantic. This correlation highlights roles of the Asian monsoon and tropical hydrological cycle in modulating global CH 4, because the high-latitude emission was inhibited during the Last Glacial Maximum (LGM). Spectral analysis of the δ18O record displays peaks at periodicities of 139, 59, 53, 43, 30, 23 and 19"15 yr. The absence of typical centennial solar cycles may be related to muted changes in ocean circulation during the LGM.