The causes of global warming & Green-house Effect

Air contains 0.03 percent of carbon dioxide. However the atmosphere content of carbon dioxide is increasing day by day due to indiscriminate use of fossil fuels. This releases carbon dioxide gas in the atmosphere. The solar energy which reaches the earth a part of it is radiated, however carbon dioxide acts as a sheet and prevents, escape radiated heat energy which now remains in the atmosphere and it gets heated. This way temperature of the earth is increasing slowly day by day. This is to referred to as ‘Global Warming’. There are some causes for increasing global warming which are given below-

5 important causes of global warming:

1.   The temperature of the earth increase due to increases use of, composition of fossil fuel which releases carbon dioxide in the atmosphere.

2.   The amount of carbon dioxide is increasing due to the use of wood as fuel.

3.   Methane’s produced in paddy field and Murphy land by rotting and decomposition of plants by bacteria and from cow dung rotten organic derbies etc. increases temperature of the earth.

4.   CFC is used in cold storage, refrigerator, motor vehicles etc. This in turn mixes in the air. It increases the temperature at high rate.

5.   The amount of nitrous oxides increases due to deforestation and use of nitrogenous fertilizer. As a result of temperature of the air has been increasing.

Means of combing be global warming:

At a global conference in 1992, 153 nations discussed on climate changes and concluded to work towards reducing the emission of green house gases mainly carbon dioxide. The measures to be taken are as follows:-

1.   Consumption of fossil fuels to be reduced the production of carbon dioxide will decreases with the reduction of use of fossil fuels.

2.   The non-conventional sources of energy such as solar energy, wing prowess etc. should be used in place of fossil fuels.

3.   Natural gas can be used in place of coal because its carbon content is half than that of coal and contains no sulphur .

4.   Fuel efficient vehicle should be designed.

5.   The production and uses of chloro-fluro carbon should be lowered as far as possible.

6.   A forestation is another step to decrease the concentration of carbon dioxide. Because plants use carbon dioxide for manufacture of food in the process of photosynthesis and release oxygen.

7.   People should be made aware about bad effects of global warming.

Green-house effect

Carbon dioxide gas present in atmosphere performs an important function in the atmosphere and produces the green-house effect, leading to the heating up of earth and its atmosphere. Let us discuss it in detail. There is a protective layer of ozone gas, high up in the atmosphere and then a blanket of carbon dioxide gas in the lower atmosphere. Now, when sun-light consisting of ultra-violet rays, visible light and infra-red rays, falls on the top of the atmosphere, then first of all the harmful ultra-violet radiation is absorbed by the ozone layer. The visible light and infra-red rays then pass through the carbon dioxide layer and fall on the surface of earth.

The infra-red rays which come down from the sun are of short wavelength and pass through the carbon dioxide layer easily. Since the infra-red radiation has heating effect, so it heats the earth and the various objects on the earth. Now, since the earth and its objects become hot, so they also start emitting heat rays or infra-red rays. But since the earth's surface and the objects on it are less hot so the infra-red rays emitted by them are of long wavelength. In other words, the infra-red rays which fall on the earth from sun are of short wavelength but the infra-red rays reflected from the earth and its objects are of long wave­length.

Now, this long wavelength infra-red radiation reflected from the earth and its objects cannot escape out from the carbon dioxide layer in the atmosphere. Since the carbon dioxide molecules have the ability to absorb the long wavelength infra-red radiation reflected from the earth, so a blanket of carbon dioxide gas in the atmosphere traps all the infra-red rays or heat rays in the atmosphere. And these trapped infra-red rays or heat rays heat the earth's atmosphere. The heating up of earth's atmosphere due to the trapping of infra-red rays (reflected from the earth's surface) by the carbon dioxide layer in the atmosphere is called green-house effect.

The green-house effect in the atmosphere occurs due to the presence of a blanket of carbon dioxide gas in the atmosphere. This blanket of carbon dioxide gas in the atmosphere allows the sunlight to come in freely but does not allow the infra-red radiation reflected by the earth's surface to go out. It is just because the sun-light can come in freely but the infra-red rays cannot go out freely that the temperature of earth's atmosphere is raised. It should be noted that the rise in temperature produced by green-house effect in earth's atmosphere depends on the amount (proportion) of carbon dioxide gas in the atmosphere.

In other words, the proportion of carbon dioxide in atmosphere affects the temperature of atmosphere. So, if the proportion of carbon dioxide gas in the atmosphere increases, then the temperature of earth's atmosphere will also rise further. The name 'green-house effect' comes from the fact that this effect is used in horticulture for the upbringing of green plants in small houses made of glass walls and glass roof. The glass walls and roof of a green-house allow the sun-light (including short wavelength infra-red rays) to come in freely but it does not allow the long wavelength infra-red radiations reflected by the soil, plants and other contents of green-house to go out. These trapped infra-red rays show their heating effect due to which the temperature is raised inside the green-house.

Thus, even without an external supply of heat, the temperature inside a green-house is found to be higher than it is outside. Thus, green-house acts as a heat trap. Due to the presence of carbon dioxide, our atmosphere acts like the glass roof of an ordinary horticultural green-house.

Nuclear Accidents and Holocaust of Ozone Depletion

Nuclear accidents can occur at any stage of the nuclear fuel cycle. The modern fusion bombs (nuclear bombs) are of explosive force of 500 kilotons and 10 megatons. Nuclear bombardment will cause combustion of wood, plastics, petroleum, forests etc.

Large quantity of black soot will be carried to the stratosphere. Black soot will absorb solar radiations and won't allow the radiations to reach the earth.

Therefore, cooling will result. The infrared radiations, which are re-radiated from the atmosphere to the earth, will have very less water vapours and carbon dioxide to absorb them. If they leave the lower atmosphere the greenhouse effect will be disturbed and cooling will occur. Due to this cooling effect, water evaporation will also reduce.

Therefore, infrared radiations absorbing water vapours will reduce in the atmosphere. This will also cause cooling. In the stratosphere there won't be significant moisture to rainout the thick soot. So due to nuclear explosions, a phenomenon opposite to global warming will occur.

This is called nuclear winter. It may result in lower global temperature. It will drastically affect crop production. Crop productivity will reduce substantially causing famines and human suffering.

The Chernobyl nuclear 1986 has resulted in wide spread contamination by radioactive substances. The devastation caused by nuclear bombs is not only immediate but may be long lasting. Towards, the end of World War II, bombing of Dresden, Germany caused huge firestorms. This caused particle laden updrafts in the atmosphere.

In nuclear holocaust in Japan 1945, two nuclear bombs were dropped on Hiroshima and Nagasaki cities in Japan. One fission bomb was dropped on Hiroshima. This holocaust (large scale destruction of human lives by fire) killed about 1, 00,000 people and destroyed the city.

This forceful explosion emitted neutrons and gamma radiations. It had a force of 12 kilotons of trinitrotoluene (TNT). The radioactive Strontium (⁹⁰Sr) liberated in the explosion resembles calcium and had the property of replacing calcium of the bones.

As a result large scale bone deformities occurred in the inhabitants of these cities. Even after more than 50 years the impacts of nuclear fallout are still visible.

Ozone depletion?

Ozone depletion?

Without our atmosphere, there would be no life on Earth. A relatively thin envelope, the atmosphere consists of layers of gases that support life and provide protection from harmful radiation. Ozone layer is a layer of the chemical ozone present in the atmosphere protecting the Earth from ultraviolet radiation. But atmospheric ozone layer depletion is a serious problem currently facing the world. The ozone layer protects humans, animals, and plants from harmful ultraviolet rays. Money and time are being spent on ozone repair, but the problem still exists.

The ozone layer is a region of the stratosphere containing ozone, or O3 gas. The ozone layer is essential to both plant and animal life on earth because it protects the surface from dangerous ultraviolet light. However, industrial and domestic chemicals that are currently in use have been found to destroy ozone, and the problem has intensified to an ozone layer “hole” above Antarctica. Ozone levels there are 40 per cent below normal, and there may be another ozone hole forming above the Arctic region.

Recently, a number of chemicals have been found to aid in the rapid destruction of ozone. Most of these chemicals are compounds called chlorofluorocarbons, or CFCs. It is difficult to ban them out rightly because they have many industrial uses. CFCs are widely used because they are non-toxic, bib-flammable, and inexpensive. Recent environmental laws on both the state and national levels have banned the use of some CFCs, but the question of their disposal still remains. Chlorofluorocarbons however do not destroy ozone directly.

There are a number of different CFCs. The compounds most responsible for ozone layer destruction are CFC-11(trichlorofluoromethane), C=CL3; CFC-12(dichlorodifluoromethane), CF2CL2; and CFC=113(1, 1, 2 trichlorotrifluoroethane), CF2CICFCL2. All of these compounds are excellent refrigerants. Some other non-CFC compounds that destroy the ozone layer include carbon tetrachloride (tetrachlorometqane), ccl4; methyl chloroform (1, 1, 1 trichloroethane), CH3CCL3; AND METHYL CHLORIDE (CHLOROMETHANE), CH3CL3

The result of ozone layer depletion is an increase in ultraviolet rays at the surface. Humans, animals, marine life, and plants are all vulnerable to UV radiation damage. Current studies indicate that ultraviolet rays could be disastrous to the marine eco-system. High UV concentration causes phytoplankton, microscopic organisms at the base of the food chain, to decrease their reproductive activity.

Numerous studies have proven that ultraviolet radiation, in both the UV-A and UV-B forms, causes skin cancer. Ultraviolet radiation has effects on plants as well, though different species react in different manners. The ozone layer is an intricate problem since the atmosphere is constantly shifting and diffusing. When the planes release the gasses, they would react with the harmful chlorine compounds and reduce their destructive power. However, the environmental effects could be shocking and it would be a complex and costly project.

Another radical approach to CFC elimination is the use of lasers. Thomas six, a Princeton university physics professor says that lasers tuned to the right frequency can break CFCs apart without affection other atmospheric gasses. The disadvantage is the cost, which would be roughly 10 billion dollars a year in electricity. One alternative being studied by major U.S. research laboratories are aerogels. Aerogels are sol-gel substances that have the insulation shape and are stronger than Styrofoam. While aerogels share many properties with plastics, they cannot be shaped as easily. Therefore, until better manufacturing technology can be implemented, aerogels will remain experimental.

There is no obvious solution to the ozone layer problem. It has been estimated that if CFC production ceased today’s, people living 70 years from now would still have to de4al with their effects. Also, conflicts between industrialists and environmentalists in government have prevented sufficient CFC blocking legislation from being fully effective. If the ozone layer can be repaired, it will take a massive effort by the people and government to make if successful.