Abstract: The global climate changes induced by natural and anthropogenic forcings over the past 2000 years has been a hot and difficult issue at the frontier of climate change research. Due to the short period of the observation and the low spatial and temporal resolution of reconstruction for the past 2000 years, Earth system modeling became a useful tool. The sensitivity of Earth system model to solar radiation versus greenhouse gases is the key of exploring divergent global climate changes induced by natural versus anthropogenic forcing, but has remained less explored so far. In this study, the Community Earth System Model(CESM 1.0)is used to do historical climate modeling for the past 2000 years. Three 2000-year simulations have been completed, namely the all forcing experiment, the solar radiation sensitivity experiment and the greenhouse gas sensitivity experiment. Based on the three experiments, we examined the sensitivity of CESM to solar radiation versus greenhouse gases preliminary. Firstly, we compared the climatology of the global temperature and the precipitation derived from the all forcing experiment to the reanalysis data, in order to verify the model performance. The characteristics of the temperature and precipitation simulated by the CESM 1.0 show similarity to the reanalysis data. The outputs of surface air temperature and precipitation from the solar radiation sensitivity experiment and greenhouse gas sensitivity experiment are compared to discuss the different sensitivity of CESM to solar radiation versus greenhouse gases. The results show that the sensitivity of CESM to greenhouse gases is larger than that to solar radiation. From the solar radiation sensitivity experiment, the global precipitation would increase 2.91% (0.078mm/day/℃) for 1℃ temperature increase, which is higher than 2.22% (0.052mm/day/℃)increase in the greenhouse gas sensitivity experiment. The spatial evolution characteristics induced by solar radiation and greenhouse gases are also different. Under the influence of solar activity, the temperature increases significantly in the northern Europe, but obvious cooling is shown in Greenland and Bering Strait. The temperature in the warm pool of equatorial western Pacific becomes higher significantly with the increase of solar radiation. However, under the influence of greenhouse gases, the temperature increases obviously in high latitude of the Northern Hemisphere. The warming strengthens gradually from north to south and an El Niño -like pattern appears in the eastern equatorial Pacific as the increase of greenhouse gas concentrations and then extended to a global warming pattern.