Escalating labor risks from sequential extreme precipitation–heatwave events in China under a warming future

: Climate warming has intensified the frequency and severity of extreme precipitation and heatwaves, yet their sequential coupling and impact on socio-economy remains poorly understood. This study defines sequential extreme precipitation–heatwave compound events (SEPHCE) and quantifies their evolving risks to China’s labor force. By integrating observations from 1929 stations (1975–2020) with CMIP6 simulations (2021–2100) under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios, we characterize a clear spatiotemporal trajectory of SEPHCE. Historically, SEPHCE frequency and duration exhibited a steady upward trend across China. Looking forward, we identify a distinct 'increase–peak–decline', pattern in frequency, projected to peak around 2060 at 2.6 times during the historically time (2001–2020), particularly in southwestern hotspots like Chongqing. Notably, while frequency may stabilize in mid-century, SEPHCE duration is projected to undergo a sustained, monotonic extension, potentially reaching 11.6 times during the historically time by 2100 under the high-emission SSP5-8.5 scenario. These shifts are expected to impose substantial labor productivity losses, with urban losses consistently 1.5-fold higher than rural ones. Our multi-duration analysis further reveals that short-duration (1-d) events will escalate five-fold longer episodes and imposing acute 'heat-shocks' on workers. These results clarify the intensifying dynamics of SEPHCE and demonstrate that while aggressive mitigation (SSP1-2.6) might alleviate long-term risks, targeted emissions mitigation is essential to safeguard future labor productivity.