Science

Pollution of Air and Water

Greenhouse Effect

You know that the sun's rays warm the earth’s surface. A part of the radiation that falls on the earth is absorbed by it and a part is reflected back into space. A part of the reflected radiation is trapped by the atmosphere. The trapped radiations further warm the earth. If you have seen a greenhouse in a nursery7 or elsewhere, recall that the sun’s heat is allowed to get in but is not allowed to go out. The trapped heat warms the green house. The trapping of radiations by the earth’s atmosphere is similar. That is why it is called the greenhouse effect. Without this process, life would not have been possible on the earth. But now it threatens life. C02 is one of the gases responsible for this effect. You know that COz is one of the components of air. You have also studied the role of carbon dioxide In plants. But If there Is excess of COz In the air. It acts as a pollutant. Can you help Pahell And out the answer to her question? On the one hand. C02 Is continuously being released because of human activities. On the other hand, area under forests Is decreasing. Plants utilise COz from the atmosphere for hotosynthesis, thereby decreasing the amount of COz In the air. Deforestation leads to an Increase In the amount of C02 In the air because the number of trees which consume C02 Is reduced. Human activities, thus, contribute to the accumulation of COz In the atmosphere. COz traps heat and does not allow It to escape Into space. As a result, the average temperature of the earth’s atmosphere Is gradually Increasing. Tills Is called global warming.