Future Extreme Precipitation in Summer Will Become More Widespread in China Depending on Level of Warming.

In this study, CMIP6 and single model initial‐condition large ensemble (SMILE) simulations were applied to reveal possible changes in the spatial coverage (RSC) of summer extreme precipitation (≥99th percentile) in China. Four different approaches were applied to provide a comprehensive assessment of RSC changes. Results indicate that the trend of RSC in summer for the period 1961–2020 in China is underestimated by raw simulations of CMIP6 multi‐model ensembles. Further analyses suggest that the confidence in model simulations reflecting the observed change can be improved based on the two observation constraint approaches and SMILE‐based approach. In addition, the reliability of the spatial distribution can also be improved. Projection results indicate that the RSC of summer extreme precipitation increases consistently with the increment of global warming across the different approaches. Among them, the results based on observational constraints and the SMILE‐based approach show enhanced reliability and present larger RSC changes than by directly using CMIP6 ensembles. In conclusion, extreme precipitation in summer is expected to become more widespread in China as the level of global warming increases. Plain Language Summary: Extreme precipitation causes severe impacts on agriculture, economy, and human health. However, it is projected by models to change in China but with low consistency. Thus, this paper provides an assessment of the projected characteristics of the ratio of spatial coverage (RSC) for extreme precipitation in China combined with multiple evidence and approaches. CMIP6 and single model initial‐condition large ensemble (SMILE) simulations are applied. Four approaches based on the statistics principle and physical interpretability are conducted to comprehensively assess change in RSC. Results reveal that extreme precipitation will become more widespread in China. Among them, results based on observation constraint approaches and SMILE‐based approach, which show enhanced accuracy and reliability, present larger RSC than directly using CMIP6 ensembles. It indicates that extreme precipitation will be more widespread in China combined with multiple evidence and methods. This study provides some scientific foundation for climate mitigation and adaptation. Key Points: Observed trend in RSC in China increased significantly in summer for the period 1961–2020 but is underestimated by CMIP6 multi‐model ensemblesConfidence is improved based on observation constraint and SMILE‐based approaches to raw model simulationsExtreme precipitation in summer will become more widespread, as supported by multiple evidence lines and approaches [ABSTRACT FROM AUTHOR]