Changes in Extreme Climate Events in China Under 1.5°C-4°C Global Warming Targets: Projections Using an Ensemble of Regional Climate Model Simulations

Extreme climate events in China, including its 10 main river basins, were projected under global warming of 1.5 degrees C-4 degrees 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 degrees C-4 degrees 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 five-day precipitation and the precipitation intensity were projected to increase significantly throughout China, while the consecutive number of dry days 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, and surface specific humidity, while the consecutive number of dry days was related to the change in summer moisture flux convergence and precipitation in dry seasons. Notably, the magnitude of the changes in extremes events was projected to increase as the warming target increases.