The Term "Green House" effect was first introduced by j. Fourier in 1827. The green house effects are the rise in temperature of earth because certain gases in the atmosphere (CO2, NO, CH4 and water vapour) absorb energy of sum.
The phenomenon is known as green house effect due to it's similarly to the heat trapping effect of glass walls in horticulture green house. In the green house visible light passes through glass and heats up soil and other soil structure. The soil emits I.R. radiations of long wavelength which are reflected back or partly absorbed by glass. This keeps the green house worm and cozy for growth of plants.
The earth atmosphere act like a glass in house. The sum is the ultimate source of energy on earth. Most of this energy is absorbed by soil, rock, and water to increase the temperature of earth's surface. Some of this energy is utilized by plant for photosynthesis process; rest of this energy is reflected back into space. At the night this energy is reradiated from the heated surface.
Mainly as infrared radiations, certain gases such as CO2, CH4, (known as green house gas) CFC'S form a blanket around the earth surface and absorb the reradiated I.R. rays and cause heating up of the earth and its environment. This is known as green house effect or global warming.
Certain optimum level of green house gases is essential to maintain desired temperature of earth to regulate life on this earth. Life on this planet is not possible without green house effect and average temperature would have been as low as -18 0C.
But due to industrialization, revolution in automobile industry the concentration of green house gases is increasing constantly. As a result of higher conc. of green house gases, scientists predict that the earth's atmosphere will be warmer and lead to global warming. It is being predicted that if proper precautions are not taken, the conc. Of green house gases in the atmosphere may double in next 50 years and may lead to increase in global temp by 4 to 50C
Effects of global warming:
1. Temperature changes: it is being predicted by computer modeling studies that if CO2 concentration is double then there is rise of 1 to 30C of global temperature from the pre-industrial time to present. At present CO2 concentration has already increased 29%.
2. Melting of polar ice cap: the increased temperature would lead to melting of glaciers and polar ice caps.
3. Rising of sea level: melting of glaciers and polar ice caps, increases the level of seas and oceans and causes flooding of low lying regions.
4. Climate changes: in the temperate regions the winter will be shorter and warmer and the summer will be longer and hotter. The tropics may become water and the sub-tropics which are already dry are expected to be drier.
5. Increase in average temperature of earth will disturb the ecosystem, affect crop production, and disturb food chain and water supplies.