./xmlchange RUN_STARTDATE=1850-01-01
./xmlchange --id CAM_CONFIG_OPTS --append --val='-cosp'
./xmlchange --id CAM_CONFIG_OPTS --append --val='-cppdefs -DCO2_BILIN_REGRID'
./xmlchange --id CAM_NAMELIST_OPTS --val "co2_cycle_rad_passive=.true. co2vmr_rad= 284.317000e-6"
./xmlchange --id CCSM_BGC --val=CO2C
