The earth gets shortwave radiation from the Sun and 1/3rd of the same is reflected and 2/3rd of the radiation is absorbed by the atmosphere, ocean, ice, land and biota. The energy absorbed from the Sun is balanced by outgoing radiation from the earth and atmosphere.
If this balance is changed, it results in imbalance, particularly it causes greenhouse effect. Greenhouse effect is a major environmental issue faced by the present world. The Greenhouse effect is enhanced by human activities that destabilize the natural balance. Green House gases (GHG) like Carbon-di-oxide CO₂, Methane CH₄, Nitrous Oxide N₂O, Water Vapour H₂O and Ozone O₃, Chloroflurocarbon CFC in the atmosphere increase Green House Effect.
The main source of Carbon-di-oxide CO₂, are through burning of Fossil fuel, wood fuel, cement manufacturing, deforestation, etc,.
The main source of Methane CH₄ is through the release from gas, oil and coal production or transmission. Enteric fermentation from ruminants such as cattle, goats, rice cultivation in Wetland, burning and decay of biomass, etc,.
The main source of Nitrous Oxide N₂O is through fertilisers, fossil fuel burning, tropical deforestation, wild fires, forest fires, etc,.
The main source of Chloroflurocarbon CFC is through the use of solvents, refrigerants, aerosol spray propellants, foam packaging, etc,.