As early as 1977, Exxon research scientists warned company executives that carbon dioxide was increasing in the atmosphere due to burning of fossil fuels, an investigation from InsideClimate Newsrevealed on Wednesday. During the 1980s, due to falling oil prices and economic pressures, Exxon began to push back on their own discoveries, saying that science was inconclusive on man-made climate change. Exxon currently denies ever doing the research.