Though carbon dioxide is present in very small proportion (0.03%) in the atmosphere, it performs very important functions as mentioned below:
1. Carbon dioxide in the atmosphere does not absorb the incoming visible radiations coming from the sun blocks the out going infrared radiations radiated by earth. By absorbing infrared radiations, the atmosphere gets heated. This is known as Green house Effect. The heated atmosphere keeps the earthworm. Thus carbon dioxide helps in keeping the earth warmer by blocking the infrared radiations.
2. The plants utilize carbon dioxide during the process of photosynthesis.
3. Ocean absorbs carbon dioxide from the atmosphere to form carbonate rocks.
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The proportion of carbon dioxide in the atmosphere is maintained constant through a number of earth processes. During certain processes, carbon dioxide is absorbed from the atmosphere while during certain other processes carbon dioxide gas is released in the atmosphere. The major consumers of carbon dioxide from the atmosphere are:
Green plants
Green plants use CO2 gas to prepare their food through photosynthesis. The oceans dissolve carbon dioxide in the form of carbonates.
The major suppliers of carbon dioxide to the atmosphere are:
- Volcanic eruptions
- Respiration by living organisms
- Decay of organisms
- Burning of fossil fuels
- Cultivation of land.
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Volcanoes release carbon dioxide into the atmosphere from the interior of the earth. All living organisms give out this gas during respiration. During respiration oxygen gas is inhaled by the living organisms while CO2 gas is exhaled. The carbon present in the organisms is converted into carbon dioxide when the organisms die and decay. The fossil fuels (such as coal, petroleum) produce carbon dioxide on combustion. The cultivation of land releases vast quantities of carbon dioxide, produced by bacteria, into the atmosphere. In this way both the atmosphere and the oceans continuously exchange carbon dioxide with the rocks, plants and higher organisms.
As already mentioned, one of the important functions of CO2 in the atmosphere is that it keeps the earth’s environment warm through greenhouse effect. Let us now study the greenhouse effect in somewhat details.