The Stanford Research Institute for the American Petroleum Institute concluded:

If the earth’s temperature increases significantly, a number of events might be expected to occur, including the melting of the Antarctic ice cap, a rise in sea levels, warming of the oceans, and an increase in photosynthesis…. Significant temperature changes are almost certain to occur by the year 2000 and these could bring about climate change.

This was in 1968!

[“Smoke and Fumes” report 1968]