Run with a subset of components (e.g. only CO2)

[ragnhibs]

Specify in the gases file which components that should be included in the model.

For CO2 only case, the RF is dependent on concentration of N2O and CH4. These can be read from the concentration input file and used in the forcing calculations, but only the CO2 forcing used as input to the energy balance model. The concentration input file then need to have concentrations for the entire time period (e.g. from the CMIP6 input or assume something after end of file).

[GlenPetersCICERO]

I tried CO2 only runs by putting all but co2 concentration to zero, and emstart=nyend, but this gives the wrong answer as the resulting forcing is non zero for many components.: SO2, SO4_IND, TROP_O3, LANDUSE, BC, OC

I repeated the above, but put all but co2 emissions and concentrations to zero and emstart=nyend, but this gives the wrong answer as the resulting forcing is non zero for many components.: TROP_O3, LANDUSE (but better than above).

In the end, I took the CO2 forcing only, made that the total forcing, and did a forcing only run.

So, methods to do co2 only run: 1) Perturbation method (2 emission driven runs, one with zero co2 emissions, and take the difference) 2) Standard run, but take co2 forcing as input into a forcing only run.

1&2 can differ slightly, depending on assumed emissions or concentrations for nonCO2, and this is probably due to the N2O effect on the CO2 forcing? Though, I have not checked this.