Trends in climate variables and their interrelationships over China are examined using a combination of observations and global climate model simulations to elucidate the mechanism for producing an observed 1¿C increase in surface temperature despite a significant decrease in surface insolation from 1950 to 2000. For the 21st century, the model simulations suggest that the downward trend in insolation is expected to continue until 2050, primarily forced by the prescribed atmospheric sulfate burden (IPCC SRES A1B). A continuous increase in surface temperature (3¿C) and vapor pressure (1mb) is simulated during the 21st century. Our analysis suggests that both the past and the future warming are primarily caused by an increase in downward longwave radiation. This occurs, in part, as a result of both the lower and upper atmospheric water vapor feedbacks, triggered by the increase in anthropogenic greenhouse gases.