@cbae: Yes, but writing today that use of leeches by 19th century doctors wasn't as prevalent as we think it was today, is quite possibly revisionist - although perhaps most doctors were against leeches being used in medicine, I have no idea. (However, leeches is a bad example because they have some valuable use, even today, to clean wounds and encourage blood clotting. We just found other ways of doing the same kind of thing. Blood letting would be a better example; although there is possible reasons why it would help some cases, in almost all cases it's a terrible idea.)
All I know for sure without literally going through papers from the 70s, is that "another ice age is coming" was a common belief and debated as widely as global warming in the public sphere.