1960s "That didn't happen" Early(ish) research on climate change is buried.

1970s "And if it did, it wasn't that bad." Severity of impacts downplayed

1980s "And if it was, it's not a big deal." Oil companies form a coalition to oppose regulation."

1990s "And if it is, it wasn't my fault." Think tanks begin switch to accepting climate change but rejecting it's anthropogenic nature."

2000s "And if it was, I didn't mean it." Oil companies try to disavow their earlier knowledge of research, engage in greenwashing.

2010s "And if I did, you deserved it." BP, among others, encourages consumers to limit their carbon footprint to save the environment, despite the fact that the majority of contribution is from industrial and commercial sources.

This timeline is sloppy. There's a lot of overlap. I'm more trying to paint a picture of what happened. In reality, the research is older. Some parties are still trying to argue the climate either isn't changing or that the earth is getting colder. Chaos is an important part of disinformation.