55 Years Ago: Mariner 2 First to Venus: “In 1962, Mariner 2 completed the first successful close-up observations of another planet when it flew by Venus… Since it orbited closer to the Sun, most scientists assumed Venus was the warmer of the two, and some believed its climate was similar to Earth’s tropics. A young scientist named Carl Sagan, however, proposed that the known high concentration of carbon dioxide in Venus’ atmosphere created a runaway greenhouse effect, leading to extremely high temperatures at the surface.”

copy/paste from an email i sent my dad in 2016 :

Scientists did not suddenly reverse themselves and start talking about global warming in the 1980s. Greenhouse gas theory (CO2 specifically) has a 120 year history of scientific study starting with John Tyndall and Svante Arrhenius in the 1890s. Here is a link to the 1958 Bell Telephone Science Hour about (among other things) climate change all cued up to the relevant section. Hardly what I would call new. The prediction of a coming Ice Age when I was a kid may have been a hit in the popular press but barely shows up in the scientific literature. Most cooling predictions were related to aerosol pollution in the atmosphere which was cleaned up in the 80s and 90s. The best that could be said about the science in the 70s was that more research was required to make a prediction. And that is what happened in the intervening 35 years, lots of research.

In the first paragraph of your link:

Some press reports in the 1970s speculated about continued cooling; these did not accurately reflect the scientific literature of the time, which was generally more concerned with warming from an enhanced greenhouse effect.