I keep thinking of that quite famous Eric Hobsbawm book on the 20th century I read a year or two ago; came out in 1994, doesn't mention the internet once (does mention E-mail though) but looking to the future at the end he brings up the upcoming climate crisis of carbon parts per million in the atmosphere.... AFAIK this book was a bestseller at the time, certainly I'd come across it as a standard textbook in various 20th century history courses as an undergrad.
It’s been mainstream science since the early 80s - the disinformation really kicked in from the mid 90s onward after public/political awareness/concern grew. The internet played a big role here I think
Exploiting the legitimate gaps in the original science (I’m talking about stuff like modelling, past temperature records, variation in suns output etc) at first. The fact that we didn’t heat up as quickly as some forcasts predicted (some early models underestimated the oceans capacity to absorb heat and co2) was hopped upon etcetc..
It often think al gore being president in 2000-2004 is one of the most interesting counterfactual/naval gazing - a president who actually believed in global warming, and might just not have buried trillions of dollars fucking up the Middle East..
But maybe it wouldn’t have made a difference