A Radiative-Convective Model Study of the CO2Climate Problem

A radiative-convective model study of the increase in global surface temperature ΔTg due to an increase in the CO2 concentration is presented. The model considers several weak bands of CO2 which contribute about 30% to ΔTg. A comparison study of the various published results with the present analysis indicates that, for the CO2 bands in the 12–18 µm region, the best estimate of ΔTg for the constant cloud top radiative-convective model is about 1.9 K for a doubling of the CO2 concentration. The inclusion of the CO2 bands in the 10 and 7.6 µm regions increases the value of ΔTg to about 2 K. The computed value of ΔTg is very sensitive to radiative-convective model assumptions regarding cloud top and relative humidity. Because of this sensitivity the estimated value of ΔTg for a doubling of the CO2 concentration ranges from 1.98 to 3.2 K.