The average global temperature is 15°C which is maintained due to presence of certain gases like C02, methane, water vapor, nitrous oxide and chlorofluro carbon present with troposphere. The gases are collectively called heat trapping or green house gases. Length’s temperature is maintained by traditional infrared (heat) radiation by these Green House effects which prevent heat from escaping to outer space, so one functionally comparable to glass panels of a green house which keep C02 concentration higher and so higher temperature inside the green house. So the effect is called Green House Effect. These Green House Effects contributes to the tune of 330C effect as in their absence, the average global temperature would save been as low as 18°C.
Global warming is the increase in average global temperature due to increase in amount of green house effects in the earth’s atmosphere.
Sources and Relative contribution of different Green House Effects to global warming:
Main sources of C02 are combustion of fossil fuels like coal oil etc (about 6.7%) in the homes and factories; process of aspiration, volcanic activities deforestation etc. It is estimated that more than 18 billion tones of C02 is produced annually from the fossil fuels. It contributes about 60% of global warming. It has increased from 280 ppm (in 1750 AD) to 368 ppm level in 2000 AD and if this trend continues, it may increase to a level between 540 and 970 ppm by the end of 21st century.
(CFCs) main sources of GFCs are refrigerators and air conditioners, plastic foams, aerosols, (chemicals present in the air as find liquid droplets) emitted is jet emission etc. These are responsible for 14% of global warming. CFCs are mainly responsible for ozone-depletion of the ozonosphere.
About 40% of methane is produced from swamps, wet lands, paddy fields guts of livestock’s like sheep’s buffaloes etc and burning of biomass during production and use of petroleum oil. It is responsible for about 20% of global warming.
Nitrous Oxide (N2O):
Its main sources are nylon products, burning of coal breakdown of nitrogen fertilizer, soil etc. It is responsible for about 6% of global warming.
Effects of Global Warming:
Rise in Sea level: Global warming will melt the polarize caps. It is estimated that if all the ice on the earth melts, about 200 feet of water would be added to the surface of all oceans. Satellite pictures have shown that the polar ice has been shrinking by 10 percent per decade since 1980.
Due to global warming, India-Khumba glacier of Md. Everest has retreated by 5km since 1953 while sea ice cover of Arctic Ocean has declined by 6% from 1978 to 1995. It is estimated that an increase of only 30C. atmospheric temperature may rise sea level by 0.2—1.5 meters over the next 50-100 years, this may submerge low lying coastal cities like Shanghai, Bangkok, Dhaka, Venice, SanFrancisco, Cairo, Sydney etc. In India this effect may also threaten the inundation of Lakshadweep Islands, Mumbai and. deltas of Ganges (West Bengal), Carvers (T.N.) Godavari (AP) and Mahanadi (Orissa).
Increase in Global Temperature:
It is estimated that if the present input trend of Green House Gases continued, then earth’s mean global temperature will rise.
A December 2003 report has predicted that global warming would be faster during the 21st century and average global temperature would be 5.5° C higher by 2100AD.
Due to global warming the following ecological problems arise-
North America will be warmer and drier while North and East Africa, India. W. Australia and Mexico will be warmer.
Desserts are likely to increase
Chances of hurricanes, cyclones and floods will more which will damage the lagoons entries etc.
Effect on Agriculture:
With increase in CO2 concentration some plants will show increased photosynthesis, reduced transpiration, more water use efficiency greater root production, increased nitrogen, fixation in the root modules etc. which may increase the growth of plants by increased evaporation decreased soil moisture, increased pest growth etc.
Effects on Human health:
Increased temperature and humidity by global warming will increase the chances of spread of vectors of a number of human diseases like malaria, fileria , Schistosomiasis etc. These climatic changes will also increase the incidence of respiratory and skin diseases in human beings.
Keeping in view these ill-effects of global warming, UNEP (United Nations Environment Programmes ) chosen the following slogan:-
Global Warming: – Global warming measures to check global warming.
Control of population growth by decreasing the birth rate.
Afforesastion (Planting more trees on new areas )
Deforestation reversal by reforestation.
Reduction in the use of cholofloro carbons.
Shift from coal to natural gas on electricity as energy resources.
To trap and use methane as a fuel.
More use of non-conventional source of energy like wind power and solar energy.
Automobiles should be made fuel efficient and less taking on the environment.