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Greenhouse Effect- Biology Guide for Class 8

Greenhouse Effect- Class 8 Science Guide

Information about Greenhouse Effect

Title

Greenhouse Effect

Class

Class 8

Subject

Class 8 Biology

Topics Covered

  • Greenhouse Effect
  • Consequences of Greenhouse Effect
  • Measures to check Global Warming

Greenhouse Effect 

The name 'Greenhouse' is given to special glass houses in which plants are grown. The plants, growing in the soil inside the greenhouse, receive the sun's radiations only through its glass walls. The temperature, inside the greenhouse, is higher than the temperature outside. This is because the rays, entering from the glass walls, (of the greenhouse) get 'trapped' there.

  • Sun rays warm the earth's surface. A part of the radiation, falling on the earth, is absorbed by it and a part is reflected back into the atmosphere.
  • Some gases, like carbon dioxide, methane, water vapours, nitrous oxide, chlorofluorocarbons, have the capacity to trap (some of) the heat radiations that are reflected from the earth. These gases are called greenhouse gases; the radiations, trapped by these gases, further warm the earth.
  • This warming effect is known as greenhouse effect. The name greenhouse effect is given to this (natural) phenomenon because it is similar to the corresponding effect in a greenhouse. 

Causes of Increase in Concentration of Greenhouse Gases in the Atmosphere

  1. Coal and wood, when burnt as domestic fuels, release carbon dioxide gas into the atmosphere.
  2. Thermal power plants use the heat produced, through burning of coal, to generate electricity. This leads to enormous release of carbon dioxide and carbon monoxide gases into the atmosphere.
  3. Indiscriminate deforestation causes imbalance in the concentration of carbon dioxide in the atmosphere. With fewer plants, consumption of carbon dioxide decreases; hence a reduced quantity of oxygen gets released back (into the atmosphere). 

Consequences of Greenhouse Effect

Global Warming

Due to greenhouse effect, the average temperature of the earth's atmosphere is gradually increasing. This is called global warming.

Likely Consequences of Global Warming

  1. Glaciers will melt at a higher rate and this will lead to a rise in the sea level resulting in floods and loss of soil.
  2. Warming of atmosphere often leads to forest fires; these have become more common over the years. 

Measures to Check Global Warming

Global warming can be checked by checking the release of greenhouse gases into the atmosphere. A number of measures have been suggested to achieve this. 
  1. The use of fossil fuels, such as wood, coal, petrol, etc., should be minimised.
  2. Electricity should be generated from hydroelectric power plants and nuclear reactors.
  3. Deforestation must be stopped.
  4. More trees should be planted.
  5. Use of chlorofluorocarbons must be reduced. 
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