Numerical Simulation of CO2 Doubling Impacts on Regional Climate in Northwest China

A numerical study on CO2 doubling effects upon temperature and precipitation in NW China is conducted using an improved regional climate model, with the modeling data from a global climate model (Australian CSIRO R21L9) as the background. Results suggest that the doubling would lead to the rise of surface temperature in the project region, with the maximum occurring in southern Xinjiang Basin and eastern Qilian Mountains in contrast to a relatively smaller increase in northern Xinjiang and southern Shaanxi Provinces. On a seasonal basis the winter temperature warming is most pronounced while the autumn shows a relatively less signi cant rising trend. The study region experiences the greatest warming compared with other parts of the country. With CO2 content doubling, rainfall change varies from place to place in this region, with rainfall increase in the west, particularly in northern Xinjiang, in the vicinity of the Tianshan area, southwestern Qinghai, and Hexi area (west of the Yellow River of Gansu), as opposed to the eastern portion of NW China, where precipitation decreases. If CO2 concentration is doubled, most of the study region would receive more rainfall in spring, implying that spring drought would be alleviated while its eastern part would see varying-degree decreased precipitation in the other three seasons, especially in summer, suggesting that drought there would be intensified in summer and autumn, thereby exerting major influence on rain-fed agriculture there.