The rise in the average temperature of the Earth (i.e. global warming) can take place in 3 ways:
1. An increase in the shortwave solar radiation that enters the atmosphere at the top
2. An increase in the percentage of the radiation that actually reaches the surface through the atmosphere (currently 70% of the total solar radiation), and
3. An increase in the concentration of the greenhouse gases in the atmosphere
The main fundamental causes of global warming are two-fold:
*The first one is our total dependence on the burning of fossil fuels to generate energy to power our industrialized lifestyles.
*The second one is the way we use our land to produce food, timber products etc.
These economic activities are the major drivers of an increase of greenhouse gas concentrations in the Earth's atmosphere.
The Green house gases are the main culprits of the global warming. The green house gases like carbon dioxide, methane, and nitrous oxide are playing hazards in the present times. These green house gases trap heat in earth’s atmosphere and thus result in increasing the temperature of earth. The excessive emission of these gases is the major cause of global warming. Actually green house gasses are the gasses which induces the green house effect. The common known green house gas is carbon-di-oxide.
The major source of carbon dioxide is the power plants. These power plants emit large amounts of carbon dioxide produced from burning of fossil fuels for the purpose of electricity generation. Coal is the major fuel that is burnt in these power plants. Coal produces around 1.7 times as much carbon dioxide per unit of energy when flamed as does natural gas and 1.25 times as much as oil. The coal gives out eighty percent more carbon per unit of energy it produces as compared to natural gas. Another major source of carbon dioxide in the atmosphere is the emission from the cars and other vehicles. About twenty percent of carbon dioxide emitted in the atmosphere comes from burning of gasoline in the engines of the vehicles. This is true for most of the developed countries. Moreover if sports bike and vehicles that are essentially designed for rough terrain, emit more carbon dioxide when used for general purpose on roads. It is always better to use vehicles designed for city driving on the city roads.
The second major greenhouse gas after carbon dioxide, which causes global warming, is Methane. Methane is more than 20 times as effectual as CO2 at entrapping heat in the atmosphere. Methane is obtained from resources such as rice paddies, bovine flatulence, bacteria in bogs and fossil fuel manufacture. Almost in all parts of the world, rice is grown on flooded fields. When fields are flooded, anaerobic situation build up and the organic matter in the soil decays, releasing methane to the atmosphere.
Another major cause of global warming is deforestation. Deforestation is to be blamed for 25% of all carbon dioxide release entering the atmosphere, by the cutting and burning of about 34 million acres of trees each year. Trees collect the CO2 that we breathe out and give away from various other sources, and they give back oxygen that we breathe in. Thus, cutting of trees is leading to greater concentration of carbon dioxide in the atmosphere. Greater urbanization, requirement of land for factories and buildings, requirement of timber are all reasons that are leading to deforestation, which in turn is leading to global warming.