Variations of the Indian summer monsoon over the last 30 000 years inferred from a pyrogenic carbon record from south-west China

The carbon isotope composition of pyrogenic carbon (δC) can be used to identify changes in terrestrial vegetation and consequently climate. We analyzed the δC values in a continuous lacustrine sediment core from the south-east edge of the Qinghai–Tibetan Plateau that spans the last 30k cal a BP, to improve our understanding of changes in regional vegetation and the Indian summer monsoon (ISM) on centennial and millennial timescales. Our data show that a mixed C/C plant community and a dry climate prevailed from 30 to 14.6k cal a BP. Monsoonal precipitation abruptly increased at the glacial–Holocene transition, and C plants growing under a humid climate dominated during the Holocene. Our record also reveals that ISM intensity decreased significantly during Heinrich Events and the Younger Dryas Chron. These findings suggest that changes in regional vegetation in south-west China are primarily controlled by ISM intensity, which in turn is related to solar insolation and high-latitude climate. This is the first δC record covering the last glacial maximum from the region, and provides insight into orbital-scale climate change and abrupt climate events that occurred in south-western China's geological past