No doubt you've heard of this concept at some point in your life. It's a hot topic of conversations - the greenhouse effect.

How Does It Work?
As sunlight nears the earth, some of it reflects straight back into space through the clouds. The remaining sunlight is absorbed by the Earth, and radiates back as heat energy. This heat energy is normally sent back to space also. However, with the accumulation of greenhouse gases, the outgoing heat radiation can NOT penetrate the earth's atmosphere, but is trapped inside. Atmospheric temperatures then increase.

Anyway, greenhouse gas emissions and deforestation are major contributors to the greenhouse effect.

Greenhouses Gases

The greenhouse gases are atmospheric gases that are responsible for causing the greenhouse effect. Some of the greenhouse gases are water vapour, carbon dioxide, methane, nitrous oxide, halogenated fluorocarbons, ozone, perfluorinated carbons, and hydro fluorocarbons.
The most significant of these are:

• Carbon dioxide (CO2)
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    Released mainly from burning fossil fuel, such as coal, oil, and wood, is the most important greenhouse gas.
• Methane (CH4)
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    Produced when animals, including humans, expell gas, and also by rotting plants. Although methane isn't as abundant as carbon dioxide, it is much more effective in absorbing heat energy because of its molecular structure.
• Nitrous Oxide
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    A gas produced by cars and coal-burning power stations. The nitrogen-based plant fertilizers used in agricultural practices also release it.
• Halogenated fluorocarbons, e.g chlorofluorocarbons (CFCs)
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    Used in air conditioners and refrigerators as coolant gases. The halogenated fluorocarbons can take more than a hundred years to break up and become harmless. This major greenhouse gas is not included in the Kyoto Protocol's specified six gases.

Deforestation

Deforestation, the combustion of trees, can greatly intensify the greenhouse effect. Combusting (burning) trees emits a huge amount of carbon dioxide, classified as a greenhouse gas. The decrease in the number of trees also means there will be less trees to convert C02 into oxygen. This inbalance in C02 emitted and absorbed leaves more greenhouse gas in our atmosphere.

There is little doubt that the greenhouse effect is caused by human activities. Having studied all the data, the Intergovernmental Panel on Climate change (IPCC) declared, "the balance of evidence suggests a discernible human influence on global climate."