This is what I came to say. There were very definite beliefs and they were pretty reasonable (although the evidence did not bear out) about global freezing in the early 1970s.

Interestingly, we might compare this with the popular idea of Nuclear Winter at the time. Essentially, a nuclear war was supposed to ignite a global conflagration that would incinerate the skies and burn so much smoke to block out the earth. But 1). The calculations were excessive in terms of the number of smoke supposedly produced and 2). Bombs became so powerful and caused such a shockwave as to almost extinguish their own fires.