Future changes of dry-wet climate regions and its contributing climatic factors in China based on CMIP6 models

Understanding future dry and wet changes under global climate change is of great regional significance in China. Based on six Global Climate Models (GCM) from the Coupled Model Intercomparison Project phase 6 (CMIP6), we project the changes of dry-wet climate regions in China in the 21st century under the three SSP-RCP (shared socioeconomic pathway-representative concentration pathway) scenarios (SSP1-2.6, SSP2-4.5 and SSP5-8.5), and further identify the key climatic factors that lead to the transition of dry-wet climate regions. The results show the area of humid and subhumid regions in China will show an upward trend in the future, while the area of semiarid and arid regions will show a downward trend. Especially under the SSP5-8.5 scenario, the area of the subhumid region has the largest increase trend (0.042% per year), and the area of the arid region has the largest decline trend (-0.048% per year). The three main transfer directions of dry-wet climate regions are from arid to semiarid regions, from semiarid to subhumid regions, and from subhumid to humid regions in the future. Due to the future extensive wetting trend in the north, the future dry-wet climate regions will shift to wetter types in Tibet, North China, the Qinling-Huaihe regions and the northeast. In addition, the key climatic factors for the transition of dry-wet climate regions are mainly precipitation, maximum temperature and solar radiation. The increase of precipitation plays a dominant role for areas projected to change to wetter types, and the increase of potential evapotranspiration (PET) plays a dominant role for areas projected to change to drier types. The PET changes in changed areas of dry-wet climate regions are mainly dominated by maximum temperature and solar radiation. Our research has important implications for future water resource management and reconsideration of climate mitigation and adaptation policies.