Mega-floods over the past 30,000 years in western yunnan, southwest China

Global warming has been leading to a significant increase in the frequency and intensity of extreme rainfall events, however, few paleoflood records hinder our understanding of its long-term patterns and underlying mechanisms. Here, we present a record of mega-floods over the past 30,000 years revealed by fossil cladoceran and geochemical proxies from Lake YunlongTianchi (YLTC) in western Yunnan, SW China. Seven mega-floods are identified in terms of abrupt changes in percentages of planktonic cladocerans, planktic-to-littoral (P/L) ratios, cladoceran flux, sedimentation rates, and terrestrial elements. They occurred at 20,410, 16,940, 15,340, 13,930, 11,540, 3,730, and 1,270 BP, when the lake catchment witnessed extreme precipitation and reduced land cover. They were triggered by extreme rainfall induced by monsoon instability, and amplified by decreased infiltration capacity due to reduced land cover. Our results suggest that these mega-floods were likely associated with monsoonal precipitation extremes as well as land cover change in the lake catchment. Our findings provide a reference for both understanding the driving mechanisms of mega-floods during geological times in western Yunnan and assessing regional extreme hydrological risks and adaptive strategies under global warming scenarios.