Global Warming & Greenhouse Effects

The greenhouse effect is a natural phenomenon that has been in place for millions of years. When the sun's rays strike the earth, a layer of gas prevents the radiant energy from escaping, which keeps Earth's temperatures suitable for life. Recently, however, concentrations of greenhouse gases have increased rapidly and considerably and have contributed to what is known as global warming. While there are many factors involved in global warming, the many forms of pollution humans are creating are responsible for increasing the intensity of the greenhouse effect.

Carbon dioxide

The primary source of carbon dioxide is combustion of fossil fuels, and it the largest contributor to greenhouse gases. Approximately one-third of the carbon dioxide in the atmosphere is due to combustion engines. Coal-burning power plants are also a big source of carbon dioxide. Widespread deforestation removes trees--usually by burning, which increases carbon dioxide even more--which remove carbon dioxide from the air, and as such is a contributor to global warming.

Water vapor

As Earth grows warmer, evaporation, and hence humidity, increases. Wter vapor is an even more effective greenhouse gas than carbon dioxide. It is possible that warmer global temperatures may be increasing the water vapor in the air, which may increase global warming even more, creating a vicious and persistent cycle.

Methane

Methane is less common, but it traps heat more than 20 times as efficiently as carbon dioxide, and as such is considered a major greenhouse gas. Primary sources of methane include flooded rice paddies, melting permafrost (which is due to global warming), coal mining, using natural gas and bovine flatulence.

Ozone

Ozone can occur at two levels in Earth's atmosphere: In the troposphere (low in the atmosphere) and in the stratosphere (higher) is a greenhouse gas. Ozone in the trophospheric level is created when oxygen is struck by ultraviolet radiation, which turns the regular oxygen molecule into an ozone molecule and occurs with the combustion of engines. Tropospheric ozone is considered to be the third most powerful greenhouse gas, following only carbon dioxide and methane.

Miscellaneous greenhouse gases

There are many other gases that are of slightly less importance but are nonetheless significant. Nitrous oxide is a greenhouse gas that is generated through the use of fertilizers and the combustion of fossil fuels. CFC (chlorofluorocarbons) can also be considered greenhouse gases, but they are not as great a threat as some of the others mentioned. CFCs are more of a threat to the ozone layer, which they break down, potentially letting more of the sun's rays enter the earth's atmosphere. The problems that CFCs cause are twofold. They not only break down ozone, which allows more radiant heat to enter the earth's atmosphere, but they are also extremely efficient at holding this heat in. High GWP (global warming potential) gases have a high capacity to hold in radiant heat. These gases (perfluorocarbons, sulfa hexafluoride and hydrofluorocarbons) are found in relatively low concentrations within the atmosphere but are dangerous because of their long persistence times.