Carbon dioxide (CO2) gas generated by man's burning of fossil fuels and the forests is responsible for about half the greenhouse gas warming. Other gases (CFCs, methane, nitrous oxide, tropospheric ozone) are responsible for the rest. Increases in all these gases are due to mankind's explosive population growth over the last century, and increased industrial expansion.
Approximately 80% of atmospheric CO2 increases are due to man's use of fossil fuels: oil, coal, and gas. These petroleum- based energy sources first came into use with the burning of coal during the industrial revolution in the 1700's. Fossil fuel use accelerated in the past 100 years, as more convenient oil and gas fuels became popular (see graph). Since 1945 petroleum consumption has increased dramatically, due in large part to increased usage of automobiles worldwide, and the substitution of mechanized farm machinery for animal power.
When world population was relatively small, no one worried about what happened to the waste products of combustion - CO2 dispersed into the seemingly limitless atmosphere and was forgotten. But now energy activities are on such a large scale that they are affecting the planet. ***
