How about some stoichiometry? The equation for the combustion of octane is 2C8H18 +25O2 -> 16CO2 +18H2O. The molecular weight of octane is 114.0. For CO2 = 44.0. This shows that if 228g is burned 704g of CO2 is produced. That's more than 3 times the mass of the gasoline you burned. It's the same result regardless of the hydrocarbon. (Coal, diesel, methane etc) Humans have been burning hydrocarbons for more than two hundred years. And CO2 is a major greenhouse gas. (It traps heat) These FACTS are why I believe humans have had an effect on the composition of the atmosphere and so climat