The burning of fossil fuels for energy and large scale forest fires such as in the tropics are major contributors o the buildup of CO 2 in the atmosphere. Managing and protecting forests and planting new trees reduces CO 2 levels by storing carbon in their roots and trunk and releasing oxygen into the atmosphere. Sulfur dioxide Burning coal to generate electricity. Hydrogen fluoride and silicon tetrafluoride Aluminum and phosphate fertilizer production, oil refineries, and steel manufacturing. Ozone Chemical reactions of sunlight on automobile exhaust gases.
Ozone is a major pollutant in smog.
Methane Burning fossil fuels, livestock waste, landfills and rice production. Nitrous oxides Burning fossil fuels and automobile exhausts. Chlorofluorocarbons Air conditioners, refrigerators, industrial foam. The greenhouse effect is created when heat from the sun enters the atmosphere and is prevented from radiating back into space by air-polluting gases. The buildup of about 40 heat-trapping gases is created mostly by human activities.