Extreme climate events in China, including its 10 main river basins, were projected under global warming of 1.5°C‐4°C using the latest version of a regional climate model (RegCM4) for dynamical downscaling, driven by the outputs of four global climate models. Firstly, evaluation indicated that the simulations satisfactorily reproduced the spatial distribution of temperature extremes and, although with lower performance, the spatial distributions of precipitation extremes were generally captured. Additionally, a better description was achieved over areas with complex terrains by using RegCM4. Next, the model was used to make projections under global warming of 1.5°C‐4°C. Warm extremes were projected to increase, while cold events were projected to decrease, particularly in northern and western China. In addition, the number of wet days was projected to increase in the northern part of China, and to decrease in the southern part. The maximum consecutive 5‐day precipitation and the precipitation intensity were projected to increase significantly throughout China, while the consecutive number of dry days (CDD) was projected to significantly decrease in northern and western China. The changes of atmospheric moisture content and atmospheric circulation lead to the increase of extreme precipitation. Specifically, the increases in the indices of wetness were closely correlated with the summer precipitation, wind, moisture flux convergence (MFC) and surface specific humidity, while the CDD was related to the change in summer MFC and precipitation in dry seasons. Notably, the magnitude of the changes in extremes events was projected to increase as the warming target increases.

Based on 24 Coupled Model Intercomparison Project Phase 5 (CMIP5) models simulations, the responses of annual precipitation and precipitation extremes (R95p and R99p defined by ETCCDI) to warming in China are analyzed. Quantitative analysis shows that the CMIP5 multi‐model ensemble (MME) underestimates the response of precipitation while overestimates the response of precipitation extremes over China region in historical period. It also has abilities in reproducing the relationships between the precipitation, precipitation extremes and the warming over subregions of China, and better performance can be found in precipitation extremes. Concurrent with the warming under the RCP4.5 and RCP8.5 scenarios, the precipitation and precipitation extremes are projected to increase consistently over China. Under the RCP4.5 and RCP8.5 scenarios, as the regional mean temperature rises by 1°C, the precipitation will increase by 3.5% and 2.4%, and the R95p will increase by 8.0% and 11.9%, respectively. The response of R99p is much more sensitive respectively with an increase of 15.3% and 21.6%. For subregions of China, they all show positive response and the regional difference will decrease in the future. Moreover, the sensitivity of the precipitation extremes to the warming is higher than that of the mean precipitation. The stronger the precipitation extreme is, the higher sensitivity it will have. Besides, the response of the mean precipitation to the warming is larger in Northern China than in Southern China. The largest increases in R95p and R99p are projected in the Tibetan Plateau and Southwest China, indicating an increased risk of heavy rainfall and floods.

Based on the homogenized daily data of 2255 meteorological stations during the past 60 years from 1961 to 2020, the potential evapotranspiration was calculated using the revised FAO56 Penman–Monteith model, and then the annual AI (aridity index, the ratio of annual potential evapotranspiration to annual precipitation) was employed to analyze the dry-wet climate change in China. The GCM models’ prediction data was used to analyze the possible trends of dry-wet climate in China by the end of this century. The results showed that in the past 60 years, the climate in China was getting wetter, especially in the western regions of China, including Xinjiang, western Qinghai, Gansu, western Inner Mongolia, and northwestern Tibet. In the last 10 years, China’s climate has become more humid. Compared with the 1960s, the total area of aridity has decreased by about 650,000 square kilometers. The changes of different climate zones have regional and periodical characteristics. There was a tendency to get wet periods in all four seasons, especially in summer. Analysis of GCM model projection data shows that by the end of this century, the climate in China would have a general trend of becoming drier. The drier regions are mainly located in the central and eastern parts of China, while the western regions of China continue to maintain the wetting trends. In the case of high emissions, the trends of drying in the central and eastern and wetting in the west are more significant than in the case of medium emission.