UNIT TEN : BIOTA AND THEIR ENVIRONMENT
ECOLOGICAL IMBALANCES
CLASS : 11
Green House Effect
The higher concentration of carbon dioxide may act as a serious pollutant. The carbon dioxide layer present in the atmosphere function like the glass panel of the green house which allow the sun light to pass through but prevent the heat from being re radiate in outer space. This is called green house effect or atmospheric effect.
Thus, increase carbon dioxide level tends to warm the air, which is called Global Warming. Bout 100 Years ago the concentration of CO2 was 275 ppm. Now it is 350ppm and by the year 2040, it is expected that it will reach to 450 ppm.
Causes of increase in CO2
Due to human civilization, excessive amount of CO2 is being deposited in the atmosphere through furnaces of power plants automobiles factories burning of coal or fossils fuels. To some extent on increase in CO2 level in atmosphere increases the rate of photosynthesis but further increase pollutes the air and water. There are other gases also which cause green house effect they are CO SO2, NO2, CH4, and CFCs
Effect of Global Warming
Green house effect results global warming which causes more floods due to melt of ice and the sea level increases. More hurricanes and cyclones occur. If the total ice of earth melt then 200 ft of water would be added to the ocean surface. A rise in sea level of 50-100 cm would flood low lands ofBangladesh and West Bengal . Within 25 years, there will be rise in sea level by 1.3-3.5 m. Then only from Bangladesh alone 15 million people will have to move. Dhaka and Calcutta may be inundated. A rise of 50C temperature of earth raises the sea level by 5m within few decades. Higher atmospheric temperature would increase evaporation of water from the farms thus reduce the crop yield.
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Biology