Goldsmith Yonaton, Broecker Wallace S, Xu Hai, Polissar Pratigya J, deMenocal Peter B, Porat Naomi, Lan Jianghu, Cheng Peng, Zhou Weijian, An Zhisheng
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964;
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964.
Proc Natl Acad Sci U S A. 2017 Feb 21;114(8):1817-1821. doi: 10.1073/pnas.1616708114. Epub 2017 Feb 6.
The magnitude, rate, and extent of past and future East Asian monsoon (EAM) rainfall fluctuations remain unresolved. Here, late Pleistocene-Holocene EAM rainfall intensity is reconstructed using a well-dated northeastern China closed-basin lake area record located at the modern northwestern fringe of the EAM. The EAM intensity and northern extent alternated rapidly between wet and dry periods on time scales of centuries. Lake levels were 60 m higher than present during the early and middle Holocene, requiring a twofold increase in annual rainfall, which, based on modern rainfall distribution, requires a ∼400 km northward expansion/migration of the EAM. The lake record is highly correlated with both northern and southern Chinese cave deposit isotope records, supporting rainfall "intensity based" interpretations of these deposits as opposed to an alternative "water vapor sourcing" interpretation. These results indicate that EAM intensity and the northward extent covary on orbital and millennial timescales. The termination of wet conditions at 5.5 ka BP (∼35 m lake drop) triggered a large cultural collapse of Early Neolithic cultures in north China, and possibly promoted the emergence of complex societies of the Late Neolithic.
过去及未来东亚季风（EAM）降雨波动的幅度、速率和范围仍未得到解决。在此，利用位于EAM现代西北边缘的一个年代测定良好的中国东北封闭流域湖泊面积记录，重建了晚更新世 - 全新世EAM降雨强度。EAM强度和北部范围在数百年的时间尺度上在干湿期之间迅速交替。全新世早期和中期湖泊水位比现在高60米，这需要年降雨量增加两倍，根据现代降雨分布情况，这需要EAM向北扩张/迁移约400公里。该湖泊记录与中国北方和南方的洞穴沉积物同位素记录高度相关，支持将这些沉积物解释为基于降雨“强度”，而非另一种“水汽源”解释。这些结果表明，EAM强度和向北范围在轨道和千年时间尺度上共同变化。公元前5500年（湖泊下降约35米）湿润条件的终止引发了中国北方新石器时代早期文化的大规模崩溃，并可能促进了新石器时代晚期复杂社会的出现。
