October 16, 1979 memo from Exxon’s W.L. Ferral to Exxon’s R.L. Hirsch about a study conducted by an Exxon summer employee named Steve Knisely. The study was on the potential impact of fossil fuel combustion on CO2 concentration in the atmosphere. Some of the conclusions in the study are:

• “present trends of fossil fuel combustion with a coal emphasis will lead to dramatic world climate changes within the next 75 years”
• “CO2 buildup in the atmosphere is a worldwide problem”
• “if it becomes necessary to limit future CO2 emissions without practical removal/disposal methods, coal and possibly other fossil fuel resources could not be utilized to an appreciable extent”