The CSIRO coupled model has been used in a “transient” greenhouse experiment. This model contains atmospheric, oceanic, comprehensive sea-ice (dynamic/thermodynamic plus leads), and biospheric submodels. The model control run (over 100 years long) employed flux corrections and displayed only a small amount of cooling, mainly at high latitudes. The transient experiment (1% increase in CO2 compounding per annum) gave a 2°C warming at time of CO2 doubling. The model displayed a “cold start” effect with a (maximum) value estimated at 0.3°C. The warming in the transient run had an asymmetrical response as seen in other coupled models, with the Northern Hemisphere (NH) warming more than the Southern Hemisphere (SH). However, the land surface response in this model is different from some other transient experiments in that there is not a pronounced drying of the midlatitudes in the NH in summer. In the control run the ice model gave realistic ice distributions at both poles, with the NH ice in particula... Abstract The CSIRO coupled model has been used in a “transient” greenhouse experiment. This model contains atmospheric, oceanic, comprehensive sea-ice (dynamic/thermodynamic plus leads), and biospheric submodels. The model control run (over 100 years long) employed flux corrections and displayed only a small amount of cooling, mainly at high latitudes. The transient experiment (1% increase in CO2 compounding per annum) gave a 2°C warming at time of CO2 doubling. The model displayed a “cold start” effect with a (maximum) value estimated at 0.3°C. The warming in the transient run had an asymmetrical response as seen in other coupled models, with the Northern Hemisphere (NH) warming more than the Southern Hemisphere (SH). However, the land surface response in this model is different from some other transient experiments in that there is not a pronounced drying of the midlatitudes in the NH in summer. In the control run the ice model gave realistic ice distributions at both poles, with the NH ice in particula...