Detailed Asian summer monsoon (ASM) variability across Heinrich stadials (HSs) 5 to 2 was reconstructed from four stalagmite oxygen isotopic (δ18O) records in central and southern China. For the last glacial period, these speleothem records, combined with previous cave records, reveal a rapid ASM decline at the onset of each HS. During this time, ASM intensity decreases immediately to the weakest level within approximately 50 years, which is followed by a gradual intensification in the mid‐HS. Typically, this process of ASM weakening is synchronous with peak ice‐rafted debris deposition and large freshwater outbursts into the North Atlantic, implying a tight link between the two. During the Holocene, however, a relatively gradual ASM decrease occurred at the start of the Bond events. Comparatively, the ASM decrease during the Bond events is generally accomplished within 110 years, and the weakest ASM occurs near the end. This difference implicates a further southward displacement of the Intertropical Convergence Zone and a stronger impact from the Atlantic meridional overturning circulation on the ASM in the early HS. Moreover, contrasting expressions of the ASM during HSs and Bond events suggest that a fixed phase relationship during bipolar climate changes cannot be expected.
One‐year‐resolved and annually‐counted stalagmite multi‐proxies (δ18O, δ13C, and layer width) from Daoguan Cave, Guizhou Province revealed detailed variability regarding the Asian Summer Monsoon (ASM) and local humidity across Bond events (BE) in the Preboreal. During BEs 8 and 7, 1.5± enrichments in δ18O values were generally consistent with high‐ to low‐latitude climate changes. In detail, the decadal‐scale minor δ18O oscillations in BE8 were broadly less than the mean value, in contrast to the significant changes in local soil moisture derived from the δ13C values and layer records. In the mid‐BE7, δ18O variability was generally above the average level, and higher‐ amplitude variations were observed in the three proxy indicators. Wavelet analysis on the total δ18O time series and across the specific time windows of BEs 8 and 7 identified periodicities of about 130, 60, and 20‐a, respectively. Exceptionally strong in BE7, the 60‐a cycle, pervasively observed in instrumental studies, became prominent starting at 11.4 kaBP. Thus, glacial background conditions are important for suppressing the ASM intensity in BE8, while during BE7, tropical hydrological circulations were potentially actively involved. Consequently, climate internal oscillations, analogous to modern conditions, might have occurred in the distant past once the link between the tropical ocean and atmosphere was established as occurs today.
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