Greenhouse Effect and Major Greenhouse Gases
The earth’s temperature has been rising during the recent past. This is due to the greenhouse effect. This term is derived from a phenomenon that occurs in a greenhouse. In order to understand the reason behind earth’s increasing temperature, it is essential to know what a greenhouse is and how does it work.
A greenhouse is basically a glass chamber in which plants are grown especially during winter season. When sunlight passes through the glass it gets absorbed inside but the greenhouse does not allow the radiations to escape. Thus, the temperature inside becomes warm enough to support plant growth.
The same phenomenon happens on the earth surface. When sunlight reaches the earth, some of it is reflected back into the atmosphere and some are absorbed by air particles. Rest of the sunlight reaches earth heating it. The earth’s surface now heats up and emits this heat in the form of infrared radiations. But a major portion of this radiation is absorbed by atmospheric gases which do not allow this heat to escape into space and radiates it back to the earth, heating it up once again. This is called greenhouse effect.
In simple words, the greenhouse effect is that property of the atmosphere which allows solar radiation to reach the earth easily but does not allow terrestrial radiation to escape from the earth easily.
The greenhouse effect is a natural phenomenon which is essential for sustenance of life on earth. It blankets the earth’s atmosphere and warms it, maintaining a suitable temperature for humans to survive but recent industrialization and urbanization has increased the emission of greenhouse gases which has exacerbated the greenhouse effect further leading to global warming.
The gases which are responsible for greenhouse effect are called greenhouse gases. These gases absorb the infrared radiations emitting from the earth and does not allow it to escape. An increase in the level of these gases has led to considerable heating of the earth.
Major greenhouse gases include the following:
Carbon dioxide: It is one of the major greenhouse gases. It is released into the atmosphere by respiration, burning of fossil fuels and organic waste and deforestation. It is also emitted during volcanic eruptions. Increased deforestation and fossil fuel burning have increased its emission. Carbon dioxide is one of the major contributors to global warming.
Methane: It is produced during the burning of vegetation and fossil fuels. A large amount of methane is also released from rotting garbage dumps, paddy fields and coal mines.
Nitrous oxide: Burning of fossil fuels, wood and crop residue releases nitrous oxide into the air.
Hydrofluorocarbons(HFCs): HFCs are man-made industrial chemicals used in air conditioning and refrigeration. They are also used as solvents, insulation foams and aero propellants. They are potent greenhouse gases with long atmospheric lifetimes and high global warming potential.
Water Vapour: It is also responsible for the greenhouse effect. Though it is not directly emitted by humans, increasing evaporation due to rising temperature has increased the concentration of water vapour in the air.
Ozone: Ground level ozone confined to troposphere contributes to the greenhouse effect. It is a secondary pollutant formed during the chemical reaction between nitrous oxide and volatile organic compounds during the presence of sunlight. Stratospheric ozone protects from ultraviolet rays of the sun but tropospheric ozone causes headache, chest pain, dryness of the throat, cough and difficulty in breathing. It also leads to cracking of rubber and extensive damage to plant life apart from contributing to global warming.
Concentration and Contribution of Greenhouse Gases to Greenhouse Effect
Concentration in Atmosphere(ppm)
Water Vapour and Clouds
Coping with the Greenhouse Effect
- Adopting cleaner fuel technologies. Instead of burning, vegetation and crop residue should be used to make bioethanol which is an eco-friendly fuel.
- Adopting non-fossil fuel based energy resources like wind energy, solar energy which do not release any harmful gases into the atmosphere.
- Promoting and adopting electric and hybrid vehicles. Also, automobiles should be properly maintained and emission control norms should be adhered to.
- Undertaking afforestation and reducing deforestation. Trees are excellent sources of carbon sequestration and help in maintaining the temperature of the earth.
- Restrictions should be imposed on industries and power plants to not exceed a certain level of fossil fuel emissions. They should be promoted to use alternative technologies which do not harm the environment.
- Devices like fabric filters, electrostatic precipitators, wet scrubbers, etc should be installed in industries to prevent the escape of harmful gases in the air.
- Carbon sequestration ( capturing and storing carbon in natural or man made sinks) could help in reducing the atmospheric and marine accumulation of greenhouse gases.