Impact of land surface degradation in northern China and southern Mongolia on regional climate

Clear evidence provided by the singular value decomposition (SVD) analysis to the normalized difference vegetation index (NDVI) and precipitation data identifies that there exists a sensitive region of vegetation-climate in- teraction located in the transitional zone over northern China and its surrounding areas, where the vegetation cover change has the most significant influence on summer pre- cipitation over China. Comparison of reanalysis data with station data provides a good method to assess the impacts of land use change on surface temperature, and the most obvi- ous contribution of land use change may be to lead to notable warming over northern China in the interdecadal time scale. Based on the new statistical results, a high-resolution re- gional integrated environmental model system (RIEMS) is employed to investigate the effects of land surface degrada- tion over the transitional zone and its surrounding areas (northern China and southern Mongolia) on the regional climate. Land degradation results in the decreases in pre- cipitation over northern and southern China, and the in- crease in between, and increased and decreased temperature over vegetation change areas and the adjacent area to the south, respectively. Not only would it change the surface cli- mate, but also bring the significant influence on the atmos- pheric circulation. Both the surface climate and circulation changes generally agree to the observed interdecadal anoma- lies over the last five decades. These integrated statistical and simulated results imply that land surface degradation over the transitional zone in northern China and its surrounding areas could be one of the main causes responsible for the climate anomalies over China, especially the drought over northern China.