Extreme East Asian summer monsoon (EASM) rainfall frequently induces floods that pose threats to millions of people across East Asia. The intensified EASM rainfall has been generally attributed to internal modes of climate variability, while external volcanic forcing has been suggested to suppress the EASM. In contrast to the hydrological weakening theory of volcanic eruptions, we present convergent empirical and modeling evidence for significant intensification of EASM rainfall in response to

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... trong tropical volcanic eruptions. Our paleoclimate proxy analyses show a significantly increased EASM in the first summer after large tropical eruptions from 1470 AD to the present. The multi-proxy ensemble mean demonstrates that the occurrence of an El Niño in the first boreal winter after a volcanic eruption is necessary for the enhanced EASM. The results from the last-millennium climate model simulations show that a volcano-induced El Niño and the associated warm pool air-sea interaction intensify EASM precipitation, overwhelming volcanic-induced moisture deficiency. This work offers a new perspective on the intertwined relationship between external forcing and internal variability in the complex climate system and potential flood disasters resulting from tropical volcanic eruption.