ii. Burning organic solids like fuel wood.
iii. Cultivation of fast growing cultivars of food crops because they undertake more photosynthesis, leading to more release of carbon dioxide.
iv. Chemical reactions in industries like the production of cement.
v. Factories emit a lot of carbon dioxide into the atmosphere.
vi. Thermal power plants based on coal are a major cause of carbon dioxide emission.
vii. Volcanic eruptions
Methane concentration has increased considerably due to:
i. Production and transport of fossil fuels
ii. Livestock like cattle and sheep
iii. Paddy fields
iv. Decay of organic wastes in landfills
The concentration of methane is increasing at a rate of one per cent. It absorbs heat about 25 times more than carbon dioxide and causes 12 per cent of greenhouse effect.
3. Nitrous oxide:
Nitrous oxide has increased in the atmosphere since the industrial revolution because of:
i. Industrial activities
ii. Waste management
iii. Burning of fossil fuels
iv. Agricultural activities like the use of nitrogen fertilizers are a major cause of nitrogen oxide emissions.
4. Fluorinated gases:
Fluorinated gases are human made gases and they include hydrofluorocarbons (HFCs), halocarbons (HCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). They are the only greenhouse gases that do not exist in nature and are created and emitted solely through human activities. They are sometimes called High Global Warming Potential (high GWP) gases.
The manufacture and/or use of refrigerators, air conditioners, foams and aerosols are the main source of fluorinated gas emissions.
The fluorinated gases have greater impact on climate change. They trap more energy than other greenhouse gases and take much longer time to disintegrate as they are man-made. Also, there are no natural processes to remove these gases.
5. Water vapour:
Water vapour is a primary gas. When temperatures rise, the amount of water vapour in the air increases due to increased evaporation from water bodies. Heat from other greenhouse gases causes more water to evaporate, releasing more vapours in the atmosphere. This vapour in turn, adds to the greenhouse effect, further warming the region.