An empirical soil carbon model was built. This simple model can directly calculate soil respiration rate if temperature and precipitation data are available. The spatial and temporal variations of net carbon fluxes between land ecosystem and atmosphere were studied. A new compiled 0.5×0.5 degree grid monthly climate data from 1901 to 1996 was used. During the past century, the global mean temperature and precipitation increased 0.6 ℃ and with a rate of 1%~2% per century, respectively. However, at dif...