The greenhouse effect is another key global environmental issue. Nowadays, it is a hot cake. Scientists are more concerned about the amount of greenhouse gases. Almost in every national and international conference or meeting on the environment, there must be a discussion about the greenhouse effect. In this article, a comprehensive discussion about the greenhouse effect, its gases and the adverse effect and benefits of the greenhouse effect.
The greenhouse is a glass made house used usually in cold countries to grow tropical plants maintaining light and temperature artificially similar to tropical climate. Greenhouse does not protect sunlight to enter, but a portion of the entered heat absorbed inside this.
What is the Greenhouse effect:
The entrapment of heat by upper atmosphere gases such as CO2, CH4 and water vapour just as glass traps heat for a greenhouse is termed the greenhouse effect. An increase in the quantities of greenhouse gases in the atmosphere result in global warming. The atmosphere is selective to respond to different types of radiation. Incoming short-wave solar radiation is transmitted to the earth without any changes, but returning long-wave radiation (infrared radiation) is not fully returned to the atmosphere and absorbed by so-called greenhouse gases in the upper atmosphere as done by the artificially made greenhouse, which allows sunlight in but traps heat inside, as described above.
Gases, which create the greenhouse effect, are called a greenhouse gas. About 20 gases are responsible for the greenhouse effect through their ability to absorb long-wave terrestrial radiation. They are all minor gases and together makeup <1% of the total volume of the atmosphere. Water vapour also exhibits greenhouse properties but received less attention than the others. From the beginning of the twentieth century, rising levels of such gases in the atmosphere associated with increasing fossil fuel use, industrial development, deforestation and agricultural activities enhanced the greenhouse effect and hence global warming (Basher, 2004). The main greenhouse effect creating gas is CO2. The other greenhouse effect creating gases are CH4, N2O (nitrous oxide), chlorofluorocarbon (CFC) and troposphere ozone. Contributions to greenhouse gases are CO2 49%, CH4 18%, CFC 14%, N2O 6% and other gases 13%.
It needs to remember here that optimum contents of greenhouse gases are favourable for the normal existence of the earth. In absence of such gases, the earth will convert to a lifeless cold planet. But it is remarkable that with the advent of modern industrialization amount of such gases increasing at an alarming rate.
Carbon dioxide (CO2) as greenhouse gases:
Carbon dioxide is non-conductive to heat and owing to this property act as cover around the atmosphere like a glass of greenhouse and keeps sphere warmer near the earth surface. With the increase in CO2 concentration, definitely increases the temperature in the atmosphere. The normal concentration of CO2 in the air is 0.03%.
Balance in CO2 concentration:
In nature, CO2 is released by lives through respiration, volcanic eruption, spring, plant and animal decomposition, limestone in contact with acid in the earth, fire and burning of wood. On the other hand in nature CO2 is absorbed by plants through photosynthesis, minerals in the earth, some of the animals in the sea for making hard shells around their bodies. Therefore, these opposite types of various activities supposed to keep the balance of CO2 concentration in the environment.
Change in CO2 concentration:
The concentration of CO2 in the environment should remain in balance because of the above-described phenomenon. But presently, activities that tend to increase CO2 concentration in the environment are:
- Burning of excessive fossil fuel such as coal, lignite, petroleum, natural gas etc.,
- Deforestation, gradual decrease of forests and breakdown of organic matter,
- Automobiles, buses, trucks and other vehicles, industrial activities etc.
The releases of CO2 from the combustion of fossil fuels and burning of the tropical forests are much larger than the breakdown of organic matter.
According to statistics of 1980 due to the destruction of tropical forests released 1659 million tons of carbon gas. According to statistics of 1950 from fossil fuel released carbon, gas was 2 billion tons and in 1988 the amount stood to more than 5 billion tons. In the atmosphere CO2 (gas that stops breathing) gradually accumulating in the upper atmosphere damaging the ozone layer through increasing temperatures of the earth. Only up to 200 years back addition and subtraction of CO2 in the environment were through natural processes. With the advent of modern industrialization around 1800 and with the invention of automobiles in 1900 use of fossil fuel was increased greatly. During this period population was also increased for which tree productions started to reduce a lot. Moreover, left materials on the forest floor through decomposition and burning also added CO2 to the environment. For this reason absorption capacity of newly produced excess CO2 in the atmosphere by vegetation was also reduced, For example, the CO2 content of the upper atmosphere was about 0.028% in pre-industrial times. It has increased to about 0.035% in the past 30 years. At the end of 1800 CO2 content in the air was 0.028% to 0.029%, at present 0.035% and the expected concentration would be 0.05 – 0.07%. Amount of CO2 that is added regularly in nature, one-fifth of this is from the destruction of tropical forests.
Nitrous oxide (N20) as greenhouse gases:
This is a naturally produced greenhouse gas. Its content in the atmosphere has increased about 25% in this century. About two-thirds of this increase is due to the combustion of coal and oil, the remainder to increased use of agricultural fertilizers.
Methane (CH4)as greenhouse gases:
Methane gas is a simple hydrocarbon and the main component of natural gas. This gas is produced from the decomposition of organic material under anaerobic conditions. Swamps and rice paddy are common sources of CH4. It is a powerful greenhouse gas, being 20 times more effective than CO2. The existing CH4 content in the atmosphere is 1.7ppm. It is better to burn produced methane although it will convert to CO2 since CH4 has more capacity to retain heat. Therefore, it is better to release less free CH4 in the atmosphere. The methane content of the upper atmosphere has essentially doubled in the past hundred years.
Chlorofluorocarbon (CFC) as greenhouse gases:
This is a compound consisting of Cl, F and C. CFC discovered in 1920, is inert, not poisonous and does not go into reactions with other materials easily. At low temperature, it evaporates and owing to this property CFC is used in refrigeration and air conditioning and in an aerosol. This is a non-conductor to heat and for this reason used extensively in the production of polymer foam. This is cheap and easy to prepare. CFC remains unchanged and mixes well in the troposphere. In troposphere CFC -11 (CC13F) is 190 ppm and CFC -12 (CC12F2) 350 ppm and their densities are increasing 5 — 8% annually. All forms of CFCs and CFC -11 CFC -12 in particular, do damage to the ozone layer. In the stratosphere in presence of ultraviolet rays of the sun, CFC breaks down to release Cl, which does the greatest damage to the ozone layer.
Adverse influences of greenhouse effect:
Every possibility is there that with the influence of the greenhouse effect a greater part of coastal regions of the world would go underwater. With the increase of temperature ice of the polar region would start to melt and the water level of the sea would come up for which low lying cities of the world including Newyork, London, Seoul, Beijing, Dhaka and many low lying areas of the world would go underwater. Maldwip being situated a few meters above the Indian Ocean the islands of the country suffer from frequent tidal waves. With the rise in the sea level due to the greenhouse effect this island country, Kiribati as a whole and part of Bangladesh would go underwater. With the rise of sea level in the regions of Asia and Pacific oceans the nature of climate will be changed. As a result, there will be loss of crops by flood, pollution in supplied water, destroy of forests, disappearance and extinction of wild animals and loss of human habitations. It is also apprehending that similar to the 1988 intense drought in the USA and flood in Bangladesh, natural calamities, drought, tornadoes and cyclones would be a regular phenomenon and more intense.
In the gradual increase in warming up of the world due to the greenhouse effect new social, economical and political problems would arise. With the rise of sea level nature of climate and use of land and its fertility would be changed. With the rise of temperature in the polar region rainfall rich tropical regions would extend up to the polar regions on one side and extended areas of the tropical region would be affected by desert on the other side. With the change in climate north and west, China would be dried and India, Bangladesh, Pakistan, Indo China, Maldip and Indonesia would receive more rainfall. In the meantime in Australia, the summer season has already been extended and rain occurs from October to March. Moreover, problems like changes in the sea flow direction, affect to fisheries, difficulties for surviving homothermous animals, increase in acidity of sweet water, extinction of animals would happen. The change in the ice-covered polar region that happened within the last two decades is very detrimental, but before that, within 0.13 million years no such changes happened in the ice caps of the world. It is guessing that sea level would rise at least 30-40 cm by 2030, because with the increase in temperature of water its volume increases. With the rise of global warming ice-covered areas of the polar region, particularly of Greenland, Canada and South America would start to melt for which sea rise would be about 1.2 m. But, if the temperature is small Antarctic ice melting would not be there and much change would not be happened within the coming 100 years.
Benefits from greenhouse effect:
Some countries of the world will be benefited from the greenhouse effect. Drier areas of China, India, Africa, Australia and the Middle-east will receive more rainfall. Melting will start in ice-covered areas of Siberia (in the Soviet Union) and in the northern part of Canada. Therefore, the present desert region and ice-covered region will become favourable for cultivation and habitations. However, these kinds of benefits are undesirable, since these would greatly disturb the overall environment in the remaining parts of the world.
Protection of greenhouse effect:
In the following ways and means greenhouse effect can be protected:
- Conservation of fuel energy can reduce the present increased production of CO2,
- Using renewable energies such as solar, water and air repeatedly,
- Developing high-quality motor vehicles that require fewer fuels per km
- Reducing the use of CO2 producing fossil fuel on the one side and inventing and using new technology that will minimize CO2 production
- Inventing alternative cheap material of CFC and stopping the use of CFC,
- Reducing the use of chemical fertilizers and introducing the use of more organic fertilizer
- Conserving existing forests and afforesting new areas
- Growing awareness about greenhouse gases politically and socially.
After this discussion discussed above, hope you will able to know about the greenhouse effect and gases. Hope, in the future international community, will give more priority to reduce the emission of greenhouse gases. To recap the concept of greenhouse effects and gases you may watch this video. Besides, if you want to know more about greenhouse effect, feel free to comment in the comment box below.