Global Warming was a Global Cooling conspiracy THEORY from the start.

FTFY

In the late 60s and 70s the "climate change" panic was promoted as a "human caused ice age". The propaganda was everywhere. Unfortunately none of the data complied with their narrative. The relatively mild increases in global temperature for the previous century or so was not helpful, so they took a decade off (the 1980s), shoving that whole "ice age" thing down the memory hole and then started pushing global warming.

If at first you don't succeed, try again in the other direction.