Late glacial and Holocene vegetation and climate variations at Lake Tangra Yumco, central Tibetan Plateau

Reconstructing vegetation and climate changes after the Last Glacial Maximum on the Tibetan Plateau (TP) is a key to understand past Indian Summer Monsoon (ISM) dynamics and the interplay between the ISM and Westerlies. In this study, a pollen record covering the last deglaciation and Holocene from Lake Tangra Yumco on the central TP is presented. A regional vegetation and climate history on the TP during the late glacial period is inferred, corresponding to long-term variations in the atmospheric circulation systems. Prior to 16,100 cal a BP, most areas of the TP are covered by treeless vegetation, mostly affected by the Westerlies. After that three major vegetation shifts to more humid-preferring vegetation types on the TP are detected during 16,100-14,600, 13,600-13,000, 12,400-10,400 cal a BP. These shifts should indicate three rapid intensifications in the ISM. During the Holocene (11400-3000 cal a BP), alpine steppe persists in the Tangra Yumco basin. Moistest conditions with strongest ISM occur prior to 8600 cal a BP. After 8600 cal a BP, climate is probably drier with a weakened ISM. Moreover, drought events at 9600-9300, 8200-7400, 5500, 4700-3700, 3200 cal a BP indicate the weakening events of ISM. Vegetation and climate changes on the central TP are mainly insolation driven, but are also associated with the influence of Holocene abrupt cold events in the North Atlantic region.