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The earth is now warmer than it would have been due to an increase in greenhouse gases which to a great extent, is natural effect predominantly caused by water vapor in form of water droplets in the air, followed closely by, in diminishing order of significance, carbon dioxide (CO2), methane (CH4) and other minor greenhouse gases such as chlorofluorocarbons (CFCs) in the air (Mac Donald, 1982). Carbon dioxide concentration in the air has been increasing significantly since the Industrial Revolution (1946) due to human actions such as deforestation and burning of fossil fuels such as coal combustion, which has seen a speedy rise in the last few decades (Lamb,1985). All other things being equal, an increase in the atmospheric carbon dioxide content suggests a rising global temperatures. It is however intricate to determine the climatic system response to the small energy amounts added by the extra carbon dioxide in the atmosphere (Gerald, 1980). The reason being that climate system is an intricate, non-linear and dynamical system, with positive and negative feedbacks, sufficient knowledge, facts and information of the causes and the expected responses of climatic changes in order to give an accurate response (Flannery, 2006).
Scientists realized that there are some gases in the atmosphere which cause an increase planet's temperature through “green house effect’ (Mac Donald, 1982). These scientists of the 19th century were predominantly interested in finding the possibility that the ice ages of the distant past were a result of a lower level of carbon dioxide gas in the atmosphere. Researchers then began to take keen interest, while trying to comprehend how the carbon dioxide level was influenced by biological and chemical forces in the past. They found that the level of carbon dioxide gas plays a vital role in the global climate change; therefore the rising level of this gas could adversely affect our future.