Long-term decrease in Asian monsoon rainfall and abrupt climate change events over the past 6,700 years
Bao Yang, Chun Qin, Achim Bräuning, Timothy J. Osborn, Valerie Trouet, Fredrik Charpentier Ljungqvist, Jan Esper, Lea Schneider, Jussi Grießinger, Ulf Büntgen, Sergio Rossi, Guanghui Dong, Mi Yan, Liang Ning, Jianglin Wang, Xiaofeng Wang, Suming Wang, Jürg Luterbacher, Edward R. Cook, and Nils Chr. Stenseth
PNAS 2021 Vol. 118 No. 30 e2102007118
Asian summer monsoon (ASM) variability and its long-term ecological and societal impacts extending back to Neolithic times are poorly understood due to a lack of high-resolution climate proxy data. Here, we present a precisely dated and well-calibrated treering stable isotope chronology from the Tibetan Plateau with 1- to 5-y resolution that reflects high- to low-frequency ASM variability from 4680 BCE to 2011 CE. Superimposed on a persistent drying trend since the mid-Holocene, a rapid decrease in moisture availability between ∼2000 and ∼1500 BCE caused a dry hydroclimatic regime from ∼1675 to ∼1185 BCE, with mean precipitation estimated at 42 ± 4% and 5 ± 2% lower than during the mid-Holocene and the instrumental period, respectively. This second-millennium–BCE megadrought marks the mid-to late Holocene transition, during which regional forests declined and enhanced aeolian activity affected northern Chinese ecosystems. We argue that this abrupt aridification starting ∼2000 BCE contributed to the shift of Neolithic cultures in northern China.
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