Stoichiometry is a fundamental concept in Chemistry Topics that deals with the quantitative relationships between reactants and products in chemical reactions.
How do Greenhouse Gases Contribute to Global Warming?
Carbon dioxide gas present in the atmosphere allows the heat rays of the sun to pass through it and reach the earth but prevents the heat rays reflected from the earth’s surface and its objects from passing out of the atmosphere into space. In this way, the sun’s heat rays remain trapped in the earth’s atmosphere and warm it up (see Figure). The warming up (or heating up) of the earth’s atmosphere due to the trapping of sun’s heat rays by carbon dioxide gas in the atmosphere, is called greenhouse effect.
The warming (or heating) of the earth produced by greenhouse effect is important for the existence of life on the earth. This is because it is due to the warming of earth by the greenhouse effect that the earth has become a habitable planet having millions of different life forms on it.
If there were no warming up of the earth’s atmosphere due to greenhouse effect produced by carbon dioxide gas in the atmosphere, the whole earth would have been converted into an extremely cold planet, making the existence of life difficult on it.
The problem, however, arises when the amount of carbon dioxide gas in the atmosphere increases too much leading to the excessive heating of earth and its atmosphere. This is discussed below.
Carbon dioxide is added to the atmosphere mainly by the burning of fossil fuels like coal, petroleum products (like kerosene, petrol, diesel, LPG) and natural gas. Carbon dioxide is removed from the atmosphere by the plants and trees for making food by photosynthesis.
These two opposing processes keep the amount of carbon dioxide in the atmosphere fairly constant. In the past, the amount of carbon dioxide gas in the atmosphere has remained low. These days, however, the fossil fuels are being burned at a very rapid rate (to meet the energy requirements of increasing population) due to which the amount of carbon dioxide gas in the atmosphere is increasing day by day. At the same time, the number of plants and trees (which remove carbon dioxide gas from the atmosphere through photosynthesis) is decreasing day by day due to deforestation and damage by acid rain.
Due to the rapid burning of fossil fuels and decrease in forests (plants and trees), the amount of carbon dioxide gas in the atmosphere is increasing steadily. The extra carbon dioxide present in the atmosphere is trapping more heat energy of the sun due to increased greenhouse effect. And because of increased greenhouse effect, the temperature of earth’s atmosphere is increasing day by day. If the proportion of carbon dioxide gas in the atmosphere goes on increasing like this, then the temperature of earth’s atmosphere will also rise further. This will lead to the excessive heating of the earth.
The undue rise in the temperature of earth’s atmosphere due to excessive greenhouse effect produced by increasing amounts of carbon dioxide gas in the atmosphere, is called global warming. Global warming is harmful to us in the following ways :
(i) Global Warming Can Cause Sea-Levels to Rise Dramatically. This will happen as follows : The rise in temperature of atmosphere due to excessive greenhouse effect or global warming will melt the enormous amount of ice lying on the poles of the earth. The huge amount of water produced by the melting of polar ice will raise the level of water in seas and oceans, and flood the low-lying areas of the earth. This will cause damage to life and property. In many places, the coastal areas have already been flooded in this way. In our country, the Gangotri Glacier in the Himalayas has started melting because of global warming.
(ii) Global Warming Can Reduce Rainfall in Some Areas of the Earth Leading to Droughts (excessive shortage of water). This can cause the death of many plants and animals, and turn large areas of the earth into semi-deserts.
Global warming is a serious threat to the existence of life on earth. Global warming has become a major concern for all the governments of the world because an increase in the earth’s atmospheric temperature by even as little as 0.5°C can have serious consequences for all. Many countries have already reached an agreement to reduce the emissions of greenhouse gases to reduce global warming and escape its harmful effects.
The Kyoto Protocol is such an agreement. An important step to achieve this goal would be to minimise the burning of fossil fuels. This can be done by using alternative sources of energy like solar energy and wind energy, etc. GREENHOUSE GASES. Those gases which can trap sun’s heat rays in the earth’s atmosphere by producing greenhouse effect leading up to the heating of earth’s atmosphere, are called greenhouse gases.
Carbon dioxide, Methane, Nitrous oxide, Chlorofluorocarbons and Water vapour, are all greenhouse gases. Carbon dioxide is the main greenhouse gas. Please note that the main constituents of the atmosphere, nitrogen and oxygen, are not greenhouse gases. They do not play any role in the greenhouse effect in nature.
Controlling Air Pollution
The air over most of the cities of our country is highly polluted. This polluted air is damaging our health and property gradually. So, air pollution must be controlled as soon as possible. Some of the ways of controlling air pollution are given below :
(i) The air pollution can be controlled by using smokeless fuels like LPG, PNG (Piped Natural Gas) and Bio-gas for cooking food (instead of wood, cow-dung cakes, or coal). Solar cookers can also be used for cooking food. Solar water heaters should be installed for obtaining hot water.
(ii) The air pollution from motor vehicles can be reduced by using CNG (Compressed Natural Gas) as fuel in place of petrol and diesel. CNG is a very clean fuel which does not pollute air.
A few years ago, Delhi was one of the most polluted cities in the world. It was being choked by fumes (exhausts) released by a very large number of cars, buses and autorickshaws running in the city on petrol and diesel. A decision was then taken by the Government to run the vehicles on fuels such as CNG and unleaded petrol. These steps have resulted in much more cleaner air for Delhi city. These days many cars, buses and autorickshaws in Delhi and other places are running on CNG.
(iii) The air pollution from factories, thermal power plants, oil refineries and chemical industries can be controlled by washing down their smoke and waste gases with jets of water. When the smoke and waste gases are sprayed by jets of water before they reach chimney, then soot present in smoke is washed away and most of the poisonous gases like sulphur dioxide and nitrogen oxides get dissolved in water.
(iv) The air pollution can be controlled by using non-polluting sources of energy like solar energy, wind energy and hydroenergy for generating electricity. This will reduce the use of fossil fuel like coal which is used for generating electricity at thermal power plants and causes air pollution.
Our Role in Controlling Air Pollution
We can also contribute in the efforts to control air pollution. Some of the steps which can be taken as individuals (or as a group of individuals) to control air pollution and improve the quality of air around us are as follows :
(i) We should not burn dry leaves, papers and garbage in the open. Leaves should be converted into compost by burying in a pit ; used papers should be sent to paper mills for recycling ; and garbage should be deposited in the garbage dumps established by the Municipal Corporation of the city.
(ii) We should save electricity. If all of us start saving electricity by avoiding its wastage in homes, schools, shops, offices and factories, the demand for electricity will decrease. This will lead to the burning of less coal to generate electricity. And burning of less coal will reduce air pollution.
(iii) We should grow more trees and also take care of the existing trees in our neighbourhood. Trees reduce pollution by absorbing excess carbon dioxide from the air. All of us should participate in Van Mahotsav functions when lakhs of trees are planted in July every year.
(iv) We should join “Say No to Crackers” campaign organised by children of many schools during Diwali days to reduce the level of air pollution during the festival season.
(v) We should use bicycle for covering short distances. This will save precious fuel like petrol (which we use in cars, scooters and motorcycles) and also reduce air pollution.
(vi) If the school is not far off, we should go to school on foot or by a bicycle. Otherwise we should use the school bus or public transport bus for going to school. In no case should we use a car individually to go to school. If, however, sufficient number of students go to the same school from an area, then a car pool can be formed for going to school.