|
(i) Water Vapour
|
- The biggest overall contributor to the greenhouse effect and humans are not directly responsible for emitting this gas in quantities sufficient to change its concentration in the atmosphere.
- CO2 and other greenhouse gases is increasing the amount of water vapour in the air by boosting the rate of evaporation.
|
|
(ii) Carbon Dioxide
|
The main sources
- The combustion of fossil fuels to generate electricity.
- The combustion of fossil fuels such as gasoline and diesel used for transportation
- Many industrial processes emit CO2 through fossil fuel combustion
- Several processes also produce CO2 emissions through chemical reactions that do not involve combustion.
- Reducing Carbon Dioxide Emissions
(a) The most effective way to reduce carbon dioxide (CO2) emissions is to reduce fossil fuel consumption.
(b) Other strategies include Energy Efficiency, Energy Conservation, Carbon Capture and Sequestration.
|
|
(iii) Methane
|
- (CH4) is emitted by natural sources such as wetlands, as well as human activities such as leakage from natural gas systems and the raising of livestock.
- Natural processes in soil and chemical reactions in the atmosphere help remove CH4 from the atmosphere
- Human induced:
(i) Agriculture: Domestic livestock such as cattle, buffalo, sheep, goats, and camels produce large amounts of CH4 as part of their normal digestive process.
(ii) Globally, the Agriculture sector is the primary source of CH4 emissions Methane is the primary component of natural gas.
(iii) Some amount of, CH4 is emitted to the atmosphere during the production, processing, storage, transmission, and distribution of crude oil & natural gas.
|
|
(iv) Nitrous Oxide
|
- (N2O) is naturally present in the atmosphere as part of the Earth’s nitrogen cycle, and has a variety of natural sources.
- Natural emissions of N2O are mainly from bacteria breaking down nitrogen emitted when people add nitrogen to the soil through the use of synthetic fertilizers, also emitted during the breakdown of nitrogen in livestock manure and urine, which Contributed to 6% of N2O emissions in 2010 emitted when transportation fuels are burned generated as a by-product during the production of nitric acid,
- Which is used to make synthetic commercial fertilizer, and in the production of adipic acid, which is used to make fibers, like nylon, and other synthetic products. Removed from the atmosphere when it is absorbed by certain types of bacteria or destroyed by ultraviolet radiation or chemical reactions.
|
|
(v) Fluorinated Gases
|
- They are emitted through a variety of industrial processes such as aluminium and semiconductor manufacturing & Substitution for Ozone-Depleting Substances.
- Very high global warming potentials (GWPs) relative to other greenhouse gases, well-mixed in the atmosphere, spreading around the world after they’re emitted.
- Removed from the atmosphere only when they are destroyed by sunlight in the far upper atmosphere, the most potent and longest lasting type of greenhouse gases emitted by human activities.
(a) Hydro fluorocarbons (HFCs),
(b) Per fluorocarbons (PFCs), and
(c) Sulphur hexafluoride (SF6).
- Hydro fluorocarbons are used as refrigerants, aerosol propellants, solvents, and fire retardants
- These chemicals were developed as a replacement for chlorofluorocarbons (CFCs) and hydro chlorofluoro carbons (HCFCs) because they do not deplete the stratospheric ozone layer.
- Unfortunately, HFCs are potent greenhouse gases with long atmospheric lifetimes and high GWPs, Per fluorocarbons are compounds produced as a by-product of various industrial processes associated with aluminium production and the manufacturing of semiconductors.
- Like HFCs, PFCs generally have long atmospheric lifetimes and high. GWPs. Sulfur-hexafluoride is used in magnesium processing and semiconductor manufacturing, as well as a tracer gas for leak detection. Sulphur hexafluoride is used in electrical transmission equipment, inducing circuit breakers.
|
|
(vi) Black Carbon
|
- Commonly known as soot, is a form of particulate air pollutant, produced from incomplete combustion, consists of pure carbon in several linked forms.
- A solid particle or aerosol, (though not a gas) contributes to warming of the atmosphere, bio mass burning, cooking with solid fuels, diesel exhaust, etc warms the Earth by absorbing heat in the atmosphere and by reducing albedo, ( the ability to reflect sunlight) when deposited on snow and ice.
- The strongest absorber of sunlight and heats the air directly, it darkens snow packs and glaciers through deposition and leads to melting of ice and show.
- Disrupts cloudiness and monsoon rainfall and accelerates melting of mountain glaciers such as the Hindu Kush-Himalayan glaciers
|
|
(vii) Brown Carbon
|
- A ubiquitous and unidentified component of organic aerosol which has recently come into the forefront of atmospheric research. Light-absorbing organic matter (other than soot) in atmospheric aerosols of various origins, e.g., soil humics, humic-like substances (HLTLIS), tarry materials from combustion, bio aerosols.
|
