Dating in the 70s
The conclusion is that at low latitudes the influence of doubling CO2 on surface temperatures is less than 0.25 K —– 208.
It appears that the 40-ppm increase over the last century may have contributed to a global temperature increase of the order of 0.2 K.Since the observed trend after 1940 has been a net cooling (see Fig. In the past century alone, the amount of CO2 in the atmosphere has increased by 40 ppm, with levels increasing at a current rate of about 0.75 Ã— 1010 tonnes per year.1), it is clear that the effect of CO2 is buried in the noise level of other unexplained fluctuations. Since the man-made contribution to the atmospheric aerosol with a long residence time is undetectable against the fluctuations in volcanic-dust loading, and since the thermal perturbations from even the largest eruptions are of the same order as other unexplained fluctuations, it can be concluded that man-generated aerosols are not exerting a measureable influence on global climate at present. Fortunately, man can tolerate CO2 levels many times present concentrations, and plant life actually grows better at increased CO2 levels.Such attempts are useful and necessary, hut they run into formidable technical difficulties.Even the mean global temperature rise caused by a given quantity of CO2 is subject to great uncertainty: and the effects of CO2 on local and time-variable phenomena (which may be crucially important to agriculture and other human activities) are more uncertain still. It appears that the much larger changes predicted by other models arise from additional water vapor evaporated into the atmosphere and not from the CO2 itself. It is important to stress…that CO2 is not the main constituent involved in infrared transfer.