Sensitivity studies on the climatic effect of an increase of atmospheric CO2

Abstract

Numerical experiments on the sensitivity of a thermodynamic model, with special reference to the climatic effect of a doubling of the atmospheric CO2, are carried out. Estimates are presented on the separate effect of including in the model the following:
a) The computation of the surface ocean temperature anomalies by the use of the conservation of thermal energy applied to the ocean mixed layer.
b) Simple parameterizations of evaporation and condensation of water vapor that do not violate the conservation of water vapor.
c) The albedo-temperature feedback.
d) A cloud layer of variable horizontal extent.
It is shown that when a), b) and c) are included in the model, the doubling of the atmospheric CO2 produces an average warming in the Northern Hemisphere, of .9°C in the surface ocean temperature, of 1.1 °c in the continental ground temperature; and an average surface temperature warming of 1.0°c. This warming increases by 0.1 °c or 0.2°c when d) is also included; and decreases by 0.2ºC when the albedo-temperature feedback effect is suppressed, and by O. 7ºC when a) is suppressed and normal surface ocean temperatures are used in the computations. Furthermore when b) is not satisfied and the parameterizations of the heat lost by evaporation at the surface and the heat gained by condensation of water vapor in the clouds areparameterized as in previous experiments, the computed surface warming decreases by 0.4°C.