The chemical composition of the atmospheric lower layer maintains constant proportions of the major gases. Carbon dioxide is frequently added to the atmosphere through the burning of domestic and industrial fuels and during the decay of organic matter. Industrialization and over populations increase the amounts of carbon dioxide in the atmosphere in excess of what can be removed through the natural biochemical cycles and pose therefore a disturbance to the environment. One such disturbance is the global increase in atmospheric temperature or global warning. The carbon dioxide gas absorbs solar radiation and affects the atmospheric heat balance. Factories add to atmospheric temperature through emissions and such poisonous pollutants as carbon monoxide (CO) and sulphur dioxide (SO2) gases. The air pollutants are returned to the surface as acids during precipitation. Excesses in oxygen are controlled by solar radiation as it breaks the oxygen molecules in ozone and adding to the atmospheric ozone layer. In an undisturbed environment, the thickness of the ozone layer is variable. It is thicker around the equator and thins away to the poles. The thicker layer shifts following the position of the sun with regard to the earth. These natural changes are solely due to the actual changes in insolation. The disturbing changes to the ozone layer are associated with emissions of industrial chemicals, largely the chlorofluorocarbons (CFC). The CFC is now believed to have reduced the ozone layer in places as to allow lethal doses of ultraviolet radiation from the sun to reach the earth. These higher than normal dozes destroy bacteria and thus pose a great danger to life. One part of the radiation from the sun is reflected by the upper layers of the atmosphere back into space or absorbed by it. The other part reaches the ground surface and is converted into infrared radiation or heat by long wave radiation. The clouds, atmospheric water vapour and atmospheric gases absorb most of the heat. These gases include carbon dioxide, methane, chlorofluorocarbons (CFC), nitrous oxide or laughing gas and ozone. These gases radiate the heat resulting in a warmer atmosphere than otherwise if these gases were present in smaller quantities. The extra levels of these gases in the atmosphere come about as a result of burning fossil fuels (petrol, diesel, natural gas, coal, etc.), firewood, and decomposition of humus in marshes and rice fields and emissions from fertilizers, factories and vehicles. Under normal conditions carbon dioxide is regulated by the carbon cycle. Plants take in carbon dioxide by photosynthesis that they convert to carbohydrates and oxygen. The carbon dioxide dissolved in the ocean is removed by photosynthesis of plankton as more is released by decay of marine organisms and diffusion. Carbon dioxide released into the upper layers of the atmosphere lasts up to a century. It is the most abundant heat-absorbing gas after water vapour and accounts for half the global warming problem-the greenhouse effect. The greenhouse effect is the warming up of the atmosphere preventing heat transfer while adding more heat as the gases and clouds absorb the heat radiated from the ground.