Different types of gases like carbon dioxide, chlorofluorocarbon, methane, oxides of nitrogen, water vapor, etc. are present in the troposphere of the atmosphere. These gases cover the earth surface making dense canopy similar to the glass frame of an artificial greenhouse. The dense canopy of different gases allows entering the solar radiations into the earth surface but does not allow escaping out after reflection. As a result, these solar radiations are absorbed in the atmosphere with increasing temperature of the earth. The phenomenon of increasing the temperature of the earth as in artificial greenhouse is called greenhouse effect. The gases which are responsible for the greenhouse effect are called greenhouse gases. Environmental scientists estimated that the effect in the greenhouse effect of carbon dioxide was 57%, chlorofluorocarbon was 25%, methane was 12% and that of oxides of nitrogen was 6%.
The sources of greenhouse gases:
The greenhouse gases are released from different human activities as well as by some natural process. Some of them are listed below:
1. Carbon dioxide gas (CO2) is produced by burning of fossil fuels (like coal, oil, natural gases), industrial, activities, automobiles, aircraft, etc.
2. Methane (CH4) is produced from the decomposition of domestic waste and sewage.
3. Chlorofluorocarbon (CFC) is released from refrigerators, air conditioners, spray cans, etc.
4. Water vapor (H2O) is released from the oxidation of organic compounds as well as vaporization of water from water sources.
Importance of greenhouse effect:
If there were no greenhouse gases in the atmosphere, all the solar radiations which were entered into the earth surface would escape into the space. As a result, heat would not be stored in the earth. Consequently, the temperature of the earth would be very less and lives would not exist on it. So, greenhouse effect is very important and responsible for sustaining lives on the earth.
Adverse effects of greenhouse effect:
Due to different types of human activities, the concentration of greenhouse gases is increasing day by day. As a result, the temperature of the earth is also increasing causing following negative effects.
1. Effects on animals
i. It helps to spread different types of diseases like malaria, fiiaria, cholera, diarrhea, etc.
ii. It helps to increase the number of pathogenic insects.
2. Effects on plants
i. It affects water cycle, soil moisture and soil composition. As a result, there is a change even in the cultivation and harvesting periods.
ii. Due to the effect of global warming, tropical plants are seen at the temperate region.
iii. It helps in breeding, growth and development of disease causing insects.