The primary interest of the present study is to examine the sensitivity of climate to radiative perturbations such as increases in CO2 and solar insolation for surface temperatures warmer than present day global averaged values (Ts> 290 K). The climate sensitivity, defined here as the change in Ts, is examined with the aid of a one-dimensional radiative-convective model. The solar insolation in the model is varied from 880 to 1840 W m−2 to obtain a wide range of Ts, from 255 to 325 K. We examine in detail the dependence of the computed ΔTs, on the following processes which are known to be important in the warmer regions (e.g., tropics) of the present day atmosphere: convective parameterizations (fixed lapse-rate, moist-adiabatic adjustment and cumulus adjustment); H2O vertical distribution; and H2O longwave radiative treatment. The climate sensitivity is shown to vary nonlinearly with Ts and to depend strongly on: (i) convective processes; (ii) H2O continuum absorption; and (iii) upper tropospher... Abstract The primary interest of the present study is to examine the sensitivity of climate to radiative perturbations such as increases in CO2 and solar insolation for surface temperatures warmer than present day global averaged values (Ts> 290 K). The climate sensitivity, defined here as the change in Ts, is examined with the aid of a one-dimensional radiative-convective model. The solar insolation in the model is varied from 880 to 1840 W m−2 to obtain a wide range of Ts, from 255 to 325 K. We examine in detail the dependence of the computed ΔTs, on the following processes which are known to be important in the warmer regions (e.g., tropics) of the present day atmosphere: convective parameterizations (fixed lapse-rate, moist-adiabatic adjustment and cumulus adjustment); H2O vertical distribution; and H2O longwave radiative treatment. The climate sensitivity is shown to vary nonlinearly with Ts and to depend strongly on: (i) convective processes; (ii) H2O continuum absorption; and (iii) upper tropospher...