Projected Changes in the Dry/Wet Climate of Chinaunder the RCP4.5 Scenario

This study projects changes in China's dry/wet climate in the 21st century using datasets from 21 climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under the RCP4.5 (Representative Concentration Pathway 4.5) scenario through soil moisture levels and a drought index, with the latter being calculated using eight surface meteorological variables. Results show that the models can reproduce the basic characteristics of the climatological dry/wet climate in China during 1986-2005, although there are some differences between the models and observations for the spatial pattern of dry climate over western China. Under the RCP4.5 scenario, the standardized precipitation evapotranspiration index and soil moisture levels would generally decrease across the whole of China, corresponding to an upward trend in the frequency of short- and long-term droughts, and a downward trend in the wet climate region. From 2016 to 2100, approximately 1.5 to 3.5 percent of the land area of China would change from a humid to semi-humid or semi-arid climate. With respect to the geographical distribution, the most obvious dryness would occur in northwestern and southeastern China where short- and long-term drought frequencies would increase remarkably, and the dryness would be detectable earlier than in other regions. Wetness would only occur in northeastern and southwestern China, but would be very weak. Seasonally, there would be warm season dryness in northern China and cold season dryness in southern China. The dryness trend of China would be primarily due to the decrease of available surface water as determined by precipitation and evapotranspiration levels.