Rapid changes in heatwaves pose dual challenge in Eastern China and its adjacent seas

This paper performs a comparative analysis of the spatiotemporal variations statistical characteristics both atmospheric heatwaves over land (AHWs) in eastern China and marine (MHWs) adjacent seas using unified heatwave definition. The multi-year average total days frequency MHWs during 1982-2019 were 5 2 times higher than those AHWs, respectively, while mean intensities AHWs unchanged. future duration will continue to increase, leading superimposed increase AHW days. decreasing increasing result nearly year-round from 2060. Under control high-pressure systems, clear skies dominate summer weather conditions its seas, which trigger heatwaves. Heatwaves turn can release substantial ocean latent heat. Enhanced convection heating further drive stronger anticyclone western North Pacific, more westward-extending Pacific subtropical high (WNPSH). Moreover, super El Niño promote an anomalous WNPSH decaying summer, may cause serious persons affected by (PAHWs) larger Plain, Yangtze River Delta, Sichuan Basin with regional sum exceeding 3 million. maximum PAHWs under SSP2-4.5 SSP5-8.5 scenarios be 3.9 billion 2076 4.7 2085, respectively. Marine ecosystems like artificial ranches coral reefs threatened longer-lasting MHWs.