Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Asian summer monsoon (ASM) variability and its long-term eco-logical and societal impacts extending back to Neolithic times arepoorly understood due to a lack of high-resolution climate proxydata. Here, we present a precisely dated and well-calibrated tree-ring stable isotope chronology from the Tibetan Plateau with 1- to5-y resolution that reflects high- to low-frequency ASM variabilityfrom 4680 BCE to 2011 CE. Superimposed on a persistent dryingtrend since the mid-Holocene, a rapid decrease in moisture availabil-ity between∼2000 and∼1500 BCE caused a dry hydroclimatic re-gime from∼1675 to∼1185 BCE, with mean precipitation estimatedat 42±4% and 5±2% lower than during the mid-Holocene and theinstrumental period, respectively. This second-millennium–BCE meg-adrought marks the mid-to late Holocene transition, during whichregional forests declined and enhanced aeolian activity affectednorthern Chinese ecosystems. We argue that this abrupt aridifica-tion starting∼2000 BCE contributed to the shift of Neolithic culturesin northern China and likely triggered human migration and societaltransformation