Coal, oil and natural gas are the three different forms of fossil fuels that are widely used. They are formed by the process of anaerobic decomposition of organic matter under the surface of the earth for millions of years. Large-scale use of fossil fuels started since the Industrial Revolution. Today, these are the most cheap sources of energy available for the use of both personal as well as commercial purposes. Petroleum is used to fuel our vehicles while coal and natural gas are used to produce electricity for our homes and offices. Statistics show that almost three-fourth of the demands of the energy in the world is fulfilled by fossil fuels.The presence of carbon dioxide in the atmosphere makes our planet warmer than any other planet of the solar system. This is because it traps the heat obtained from sunlight and do not let it go beyond the atmosphere. Burning fossil fuels releases a large amount of carbon dioxide into the air. When there is a significant rise in the percentage of carbon dioxide in the air, the amount of heat captured by the carbon dioxide gas also increases. This in turn leads to overall rise in the surface temperature of the earth which is also known as global warming.Evidence obtained from various research studies suggest that since the middle of the nineteenth century, carbon dioxide content in the atmospheric air has increased at least, 25 percent. This is mainly because of excessive use of fossil fuels all across the globe. For this reason, in the last 150 years, the temperature of the earth has already gone up more than 1 degree Fahrenheit. It is estimated that the temperature is going to increase further in the next hundred years. Thus our planet will be much hotter in the next century.