Late Holocene Indian summer monsoon evolution and centennial fluctuations inferred by grain size sensitive component from Lake MangCo, southeastern Tibetan Plateau

Dongliang NING ¹ Weiwei Sun ² Dejun Wan ^1* Longjuan Cheng ¹ Qingfeng Jiang ¹

• ¹ Nantong University, Nantong, China
• ² State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology (CAS), Nanjing, Jiangsu Province, China

Identifying the late Holocene Indian summer monsoon (ISM) changes and the possible forcing mechanism provide windows to understand the current shifts in the monsoon system driven by anthropogenic climate change in a natural baseline. In this study, we present a well-dated, ca. 4.0 ka grain size sensitive component record from Lake MangCo, southeastern Tibetan Plateau. The record depicts the late Holocene ISM evolution and centennial-scale precipitation events superimposed on the millennial-scale climate change. The results indicate that the precipitation was high during the first half of the late Holocene likely before 2.0 cal ka BP and followed by a relatively low interval thereafter, which indicates the north hemisphere summer insolation has primarily controlled the ISM intensity. A slight increasing trend in ISM since 1.1 cal ka BP was also observed that might correspond to the reported “2.0-kyr-shift” and be related to warmer tropical temperature. Three low precipitation intervals occurred at ~1.1, 2.0 and 3.2 cal ka BP corresponding well with centennial ISM weakening events during the late Holocene such as the medieval warm period and the “2.0-ka-dry-event”. Our findings further validate the climatic effects of tropical ocean-atmospheric interactions in the Pacific and Indian Ocean basins on ISM variabilities on centennial scales.