What I hate about these things is the lack of any context, one sentence for no doubt many paragraphs of press release. Were they talking about the no-feedback sensitivity? If so it's certainly lower than the 1 C per doubling of CO2 as proposed these days.
Had a look for GISS papers around this time, only found one so far w.r.t this, from 1971: (maybe one of the sources of the silly "every scientist predicting an ice age" meme)."Abstract
Effects on the global temperature of large increases in carbon dioxide and aerosol densities in the atmosphere of Earth have been computed. It is found that, although the addition of carbon dioxide in the atmosphere does increase the surface temperature, the rate of temperature increase diminishes with increasing carbon dioxide in the atmosphere. For aerosols, however, the net effect of increase in density is to reduce the surface temperature of Earth. Because of the exponential dependence of the backscattering, the rate of temperature decrease is augmented with increasing aerosol content. An increase by only a factor of 4 in global aerosol background concentration may be sufficient to reduce the surface temperature by as much as 3.5 ° K. If sustained over a period of several years, such a temperature decrease over the whole globe is believed to be sufficient to trigger an ice age."
Rest available IF you are an AAAS member
https://science.sciencemag.org/content/173/3992/138
