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Speleothem δ¹⁸O records from central southern China have long been regarded as a key benchmark for Asian summer monsoon intensity. However, the similar δ¹⁸O minima observed among precession minima and their link to seasonal precipitation mixing remains unclear. Here, we present a 400,000-y record of summer precipitation δ¹⁸O from loess microcodium, which captures distinct precession cycles similar to those seen in speleothem δ¹⁸O records, particularly during glacial periods. Notably, our microcodium δ¹⁸O record reveals very low-δ¹⁸O values during precession minima at peak interglacials, a feature absent in speleothem δ¹⁸O records from central southern China. This discrepancy suggests that the mixed summer and nonsummer climatic signals substantially influence the speleothem δ¹⁸O records from central southern China. Proxy-model comparisons indicate that the lack of very low-δ¹⁸O values in speleothem δ¹⁸O records is due to an attenuated summer signal contribution, resulting from a lower summer-to-annual precipitation ratio in southern China at strong monsoon intervals. Our findings offer a potential explanation for the long-standing puzzle of the absence of 100- and 41-kyr cycles in speleothem δ¹⁸O records and underscore the critical role of seasonality in interpreting paleoclimatic proxies in central southern China. These insights also have broader implications for interpreting speleothem δ¹⁸O records globally, advocating for a more multiseason interpretive framework. 

Protracted droughts lasting years to decades constitute severe threats to human welfare across the Indian subcontinent. Such events are, however, rare during the instrumental period. since 1871 CE). In contrast, the historic documentary evidence indicates the repeated occurrences of protracted droughts in the region during the preinstrumental period implying that either the instrumental observations underestimate the full spectrum of monsoon variability or the historic accounts overestimate the severity and duration of the past droughts. Here we present a temporally precise speleothem-based oxygen isotope reconstruction of the Indian summer monsoon precipitation variability from Mawmluh cave located in northeast India. Our data reveal that protracted droughts, embedded within multidecadal intervals of reduced monsoon rainfall, frequently occurred over the past millennium. These extreme events are in striking temporal synchrony with the historically documented droughts, famines, mass mortality events, and geopolitical changes in the Indian subcontinent. Our findings necessitate reconsideration of the region’s current water resources, sustainability, and mitigation policies that discount the possibility of protracted droughts in the future. 

The 4.2 ka event is widely presumed to be a globally widespread aridity event and has been linked to several episodes of societal changes across the globe. Whether this climate event impacted the cultural development in south-central China remains uncertain due to a lack of regional paleorainfall records. We present here stalagmite stable carbon isotope and trace element–based reconstruction of hydroclimatic conditions from south-central China. Our data reveal a sub–millennial scale (~5.6 to 4.3 ka) drying trend in the region followed by a gradual transition to wetter conditions during the 4.2 ka event (4.3–3.9 ka). Together with the existing archaeological evidence, our data suggest that the drier climate before 4.3 ka may have promoted the Shijiahe culture, while the pluvial conditions during the 4.2 ka event may have adversely affected its settlements in low-lying areas. While military conflicts with the Wangwan III culture may have accelerated the collapse of Shijiahe culture, we suggest that the joint effects of climate and the region's topography also played important causal roles in its demise. 

Abstract. Although the collapses of several Neolithic cultures in China areconsidered to have been associated with abrupt climate change during the4.2kaBP event (4.2–3.9kaBP), the timing and nature of this event andthe spatial distribution of precipitation between northern and southern Chinaare still controversial. The hydroclimate of this event insoutheastern China is still poorly known, except for a few published recordsfrom the lower reaches of the Yangtze River. In this study, a high-resolutionrecord of monsoon precipitation between 5.3 and 3.57kaBP based on astalagmite from Shennong Cave, Jiangxi Province, southeast China, ispresented. Coherent variations in δ¹⁸O and δ¹³Creveal that the climate in this part of China was dominantly wet between 5.3and 4.5kaBP and mostly dry between 4.5 and 3.57kaBP, interrupted by awet interval (4.2–3.9kaBP). A comparison with other records frommonsoonal China suggests that summer monsoon precipitation decreased innorthern China but increased in southern China during the 4.2kaBP event.We propose that the weakened East Asian summer monsoon controlled by thereduced Atlantic Meridional Overturning Circulation resulted in thiscontrasting distribution of monsoon precipitation between northern andsouthern China. During the 4.2kaBP event the rain belt remained longer atits southern position, giving rise to a pronounced humidity gradient betweennorthern and southern China.