At the time there had been a slight cooling from the 1940s thru late 1970s (or at least no warming as would be expected by the enhanced greenhouse effect). See the chart:
There is the natural process of glacial-intergacial cycles – but such a cooling would have taken many many 1000s of years and nothing to worry about.
The main issue for scientists was the aerosol effect from SO2 and particulate matter (regular pollution that make the atmosphere hazy, that is emitted along with GHGs) – that was known to have a cooling effect, but they didn’t know how much. A very few scientists were saying it could trigger a cooling. The earth systems are fairly sensitive to warming and cooling “forcings”; initial cooling if enough could cause more snow and ice to form, reflecting more heat away from earth, causing still more snow and ice to form – not a “snowball earth” as happened in the distant past, but more significant cooling.
To complicate matters, there was fear of a “nuclear winter” back then; if nuclear war happened, it could kick up enough dust to cause enough cooling to wipe out agriculture.
However, most climate scientists felt this leveling off in the warming back then was just temporary due to this aerosol cooling effect, and other natural fluctuations, and that the GHGs were more potent and that warming (not cooling) would be happening in the long run.
See an article in Science from 1981 (r/t Time & Newsweek) – the predictions are pretty good re what actually has happened, considering the science and computer power back then were not nearly as advanced as today: pubs.giss.nasa.gov/docs/1981/1981_Hansen_etal.pdf
Also see: realclimate.org/wiki/index.php?title=They_predicted_global_cooling_in_the_1970s
For one thing, aerosol molecules have a short lifespan in the atmosphere – a few weeks – while GHGs have a much longer residency, about 10 years for methane (CH4) and over 100 years for CO2, and now they know a portion of CO2 molecules emitted today can stay in the atmosphere for up to 100,000 years.
I guess at the time in the 70s cooling was scarier than warming, so the media went wild after the cooling story and didn’t pay much attention to the warming story.
We should, however, understand that science progresses as time marches on, and should not dwell on science of 40 years ago when we have better science today.
Also the argument that global warming has stopped, or its cooling now is also bogus, with some of the same factors as mentioned complicating the picture – including the need to look at many decades (not just one or two); the natural fluctuation in solar irradiance (it’s been in a minima for some 15 years, but there has been no cooling back to pre-1960s level to match); increased aerosol pollution from China and other developing nations as they become developed; uptake of the warming in the ocean and ice-melting processes. See:
Here’s a graphic that helps:
There is no reason so expect a cooling at this point; some scientists are even saying that earth may never again go into an ice age, esp since the sun is also gradually heating up, and gives off a lot more heat than millions of years ago. They even think the regional mini-cooling, as portrayed in Day After Tomorrow with the halting or slowing of the deep ocean (thermohaline) circulation, would not have much cooling effect in the north Atlantic region, due to warming overpowering that effect. However, new research does indicate we could get more negative arctic oscillations with global warming – bringing cold snaps north to south more often – killing my winter veggie garden and tropical plants – instead of the more typical west-to-east pattern, leaving the arctic much warmer in places. This happening while the global average temps continue to warm.
Also, now there is mountains of evidence that warming will be having a net negative effect on life on earth, including on human life, so it really is a life issue, and any truly pro-life person concerned about the children and progeny will be taking it seriously and striving to do their part. The gov can only do so much, the bulk of the mitigation solutions will have to come from ordinary people.