Plenty of examples, but here are a few:

By 1978 Exxon’s senior scientists were telling top management that climate change was real, caused by man, and would raise global temperatures by 2-3C this century, which was pretty much spot-on.

By the early 1980s they’d validated these findings with shipborne measurements of CO2 (they outfitted a tanker with carbon sensors for a research voyage) and with computer models that showed precisely what was coming.

1989 presentation to Board of Directors: “In spite of the rush by some participants in the greenhouse debate to declare that the science has demonstrated the existence of [global warming] today, I do not believe such is the case."