GLOBAL WARMING

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 Global warming

The greenhouse effect at it natural level is very essential for life to exist on this planet ( earth) , but its increase (enhanced greenhouse effect) as is actually taking pqlce, is feared to cause global climatic changes of irreversible and highly destructive type. The greenhouse effect is in fact normal to earth and essential to life. Without it, the earth would be over 30°C cooler and life as we know would not exist. 

The Energy of the Sun is emitted as heat radiations. Some of the heat radiations reach the earth surface and are absorbed and retained by the earth surface. Some of this absorbed heat is then re-radiated by the heated earth surface . the temperature of the earth surface is determined by the energy balance between the heat energy reaching the earth surface and the heat energy that is radiated back into space. 

Troposphere, the lowermost layer of the atmosphere , traps heat by a natural process due ti the presence of certain gases. This effect is called greenhouse effect. The among of heat trapped in the atmosphere depends mostly on the concentrations of greenhouse gases and the length of time they stay in the atmosphere. The major greenhouse gases are carbon dioxide, methane,chloroform carbon l, nitrous oxide, ozone and water vapours. The average global temperature is 15°C. In the absence of greenhouse gases this temperature would have been 18°C . thus the greenhouse effect contributes a temperature rise of 33°C . Heat trapped by greenhouse gases in the atmosphere keeps the planet warm enough to allow us and othervspecies to exist  the two predominant greenhouse gases are water vapours and carbon dioxide  while the levels of water vapours in the troposphere have relatively remained constant , the levels of carbon dioxide have increase other gases whose levels have increased due to human activities are methane (CH4) nitrous oxide (N2O) and chlorofluorocarbons ( CFCs). 

  Thus the increase in the concentration of greenhouse gases is enhancing the greenhouse effect thereby increasing the average surface temperature beyond 15°C . On the global scale, this effect is known as global warming.

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