The impact of uniform and nonuniform CO2 concentrations on global climatic change

The spatial-seasonal distributions of carbon dioxide (CO2) data derived from satellite observation data are introduced into the coupled BNU-ESM (Beijing Normal University Earth System Model) global model to study the differences in global atmospheric temperature changes caused by the uniform and nonuniform distributions of CO2. A series of ensemble simulations are conducted under different CO2 distributions from 1850 to 2005. From the seasonal to interannual scale, the spatial distributions of CO2 concentration and surface air temperature between the nonuniform and uniform simulations are different. The CO2 concentrations in the nonuniform simulations are higher than those in the uniform simulations in most areas of the Northern Hemisphere and lower in almost all of the Southern Hemisphere; however, the air temperatures are higher in the nonuniform simulations than in the uniform simulations over most land areas, especially in North America. The amplitudes of the temperature increase in both ensemble runs (nonuniform-uniform) from 1986 to 2005 caused by increases in the CO2 concentration are smaller in the Southern Hemisphere than in the Northern Hemisphere. The amplitudes of the temperature increase over the two decades in the ensemble uniform simulation is approximately 0.2~0.3 degrees C higher than that in the ensemble nonuniform simulations at the global scale.