The Earth has a natural temperature control system. Earth's atmosphere is primarily composed of nitrogen that is 78 percent% and oxygen is 21%. These atmospheric gases restrict absorption of infrared energy. Only the greenhouse gases, which make up less than 1 percent of the atmosphere, offer Earth insulation. The greenhouse effect is a naturally occurring process that aids in heating the Earth's surface and atmosphere. The greenhouse effect causes the surface of the Earth to be warmer than it would have been in the absence of an atmosphere. The greenhouse effect has warmed Earth for over 4 billion years. The greenhouse effect, first discovered by Joseph Fourier in 1824, and first investigated quantitatively by Svante Arrhenius in 1896, is the process by which an atmosphere warms a planet.

The earth has a natural greenhouse effect due to trace amounts of H20 and CO2 that naturally occur. The greenhouse effect results from the interaction between sunlight and the layer of greenhouse gases in the atmosphere that extends up to 100 km above Earth's surface.

Sunlight is composed of a range of short-wavelength radiant energies, which includes visible light, infrared light, gamma rays, X rays, and ultraviolet light. As energy from the Sun passes through the atmosphere a number of things take place. When the Sun's radiation reaches Earth's atmosphere and it becomes a radiator of energy of long-wavelength radiation.

• About one third of the solar radiation that hits the earth is reflected back to space.
• About 20 percent is absorbed in the atmosphere and the land and oceans absorb most.
• About 51% of the Sun's radiation reaches the surface.

The Earth's surface becomes warm and as a result emits infrared radiation. The greenhouse gases trap the infrared radiation, thereby insulating and warming the planet. The energy is then used in a number of processes including:

• The heating of the ground surface
• The melting of ice and snow.
• The evaporation of water.
• Plant photosynthesis.

Naturally occurring greenhouse gases include:

• Water vapors which causes about 36-70% of the greenhouse effect on Earth.
• Carbon dioxide (CO2), which causes 9-26%.
• Ozone, which causes 3-7%.
• Methane (CH4).
• Nitrous oxide (N2O).

Human-made chemicals that act as greenhouse gases include

• Chlorofluorocarbons (CFCs).
• Hydro chlorofluorocarbons (HCFCs).
• Per fluorocarbons (PFCs).
• Nitrous oxide (N2O).
• Tropospheric ozone (O3).

The heat-trapping gases in the atmosphere behave like the glass of a greenhouse. These gases absorb infrared radiant heat, temporarily preventing it from dispersing into space. As these atmospheric gases warm, they emit infrared radiation in all directions. Some of this heat returns back to Earth to further warm the surface in what is known as the greenhouse effect.

Without the thermal blanketing of the natural greenhouse effect, life on earth would probably not exist, as the average temperature of the Earth would be a chilly -18° Celsius, rather than the present 15° Celsius.

The concentrations of greenhouse gases have increased since the beginning of the Industrial Revolution. As a result, the greenhouse effect has enhanced and the Earth's climate has become warmer and the global temperature has risen between 1 and 3° Celsius.

The enhanced greenhouse effect refers to the augmentations of these natural gases by human activities. It is the increase in the amounts of these gases through human activity that causes global warming.Increases in the earth's temperature can occur:

• Naturally as a result of climatic fluctuations caused by solar cycles and changes in the sun's radiation.
• Human activity such as burning of fossil fuels (coal, oil and natural gas), Land clearing and Agriculture.

Mankind has devised many inventions that burn fossil fuels such as coal, oil, and natural gas. However, this progress has come at a cost of the exploitation of nature.

The greenhouse effect is beneficial to the Earth. The greenhouse effect is an essential environmental prerequisite for life on Earth. The problems begin when human activities distort and accelerate the natural process by creating more greenhouse gases in the atmosphere than are necessary to warm the planet to an ideal temperature. It is only when human-made processes increase its speed that the problems occur.

There are natural as well as human-made causes of the greenhouse effect.

• The emissions of gases like nitrous oxide, carbon-di-oxide, methane, ozone and water vapors.

• Deforestation-forests are logged for timber or cut down to make way for farming.
• Burning of fossil fuels, oil, coal and gas including gasoline for automobile engines raises the level of carbon dioxide in the atmosphere.
• Emission of gases like Chlorofluorocarbons (CFCs) from electrical appliances.
• Farming and land-use changes increase the levels of methane and nitrous oxide.
• Population growth processes.
• Factories produce industrial gases.

• Rising temperatures would raise sea levels.
• The world's endangered species would become extinct.
• Certain vector-borne diseases carried by animals or insects, such as malaria, would become more widespread as warmer conditions expanded their range.
• Melting parts of polar ice caps and most mountain glaciers.
• Prolonged drought or increased flooding in some of the world's leading agricultural regions.

• Reducing use of fossil fuels would reduce the amount of carbon dioxide produced.
• Reducing the levels of the pollutants that cause acid rain. This can be achieved by either using less energy or alternative energy sources.
• Eliminating the use of CFCs is something we can actually do.
• Stopping deforestation by using renewable forests and planting a new tree.
• Making lifestyle choices that help to sustain the environment.