Persistent ENSO Forcing on Holocene Flooding in the Middle-Lower Yangtze River at Millennial Timescales

Abstract

El Niño-Southern Oscillation (ENSO) is the most dominant interannual signal of climate variability and profoundly affects river flooding globally, especially in East Asia. However, ENSO also has ∼2,000 and ∼1,000-year cycles, but due to the lack of flood records with sufficient length, little is known about the ENSO's impact on floods at these millennial timescales. Here we test this in the middle-lower Yangtze River by reconstructing the first Holocene flood record with optically stimulated luminescence and 14C ages of flood deposits. We find the periods with high flooding probability generally correspond with intervals of weakened solar activity. Importantly, the flood record displays 2,000 and 1,000-year cycles similar to the ENSO record, and band-pass filter results show the two records are synchronous at these bands. Our results reveal a persistent control of ENSO on millennial-scale hydroclimatic variability in the Yangtze basin and likely other basins.