| In RFMIP-ERF-HistAer and RFMIP-ERF-Aer, ozone concentrations should be fixed at pre-industrial values. In concentration-based models, the concentrations of ozone should be fixed, and in emissions-based models, the ozone in the radiation code should be fixed. As solar and volcanic forcings affect stratospheric ozone, this effect will be included in the hist-nat integration of DAMIP. To get a consistent ERF estimate modeling groups should include the same dataset in the RFMIP-ERF-HistNat experiment. David Plummer, in collaboration with Michaela Hegglin, has kindly agreed to develop prescribed ozone datasets for DAMIP hist-nat, which account for solar and volcanic effects and that data will be published on input4MIPs in due course. Therefore, we suggest that modeling centers using models without coupled chemistry wait until the prescribed ozone datasets are available before commencing these experiments.