Though the first clear scientific warnings about global warming came at the same that Milankovitch Cycles were defined, succeeding clarions were sounded more and more until in 1965 government and oil industry leaders sounded a warning that was clear and dire — and the source unexpected. “This report unquestionably will fan emotions, raise fears, and bring demand for action,” the president of the American Petroleum Institute (API) told an oil industry conference, as he described research into climate change caused by fossil fuels.
https://www.desmogblog.com/2018/11/20/american-petroleum-institute-1965-speech-climate-change-oil-gas
Every President Since JFK Warned About Climate Change:
https://www.eenews.net/stories/1060105233
https://skepticalscience.com/LBJ-climate-1965.html