global warming

 Global warming refers to the rising global temperature. It causes climate change that is responsible for; flood; frequent and intense rain and snow; change in the normal occurrence of monsoon thereby affecting crop production; drought; landslide; vector born diseases; more frequent tropical stroms;  forest fire and extinction of species due o the loss of ecological niches.

   Scientist all over the world believe that global  warming is mainly  caused by two processes as given below:

1)Increase in the level of green house gases such as carbon dioxide(co2),chlorofluorocarbons(CFCS), methane and water vapour due burning of fossil fuel and deforestation.

2)  Milankovitch cycle

        According to milankovitch cycle, there is a periodic change in the Earth’s orbit and rotation around the sun that alter solar radiation reaching the Earth and cause global warming   as well as cooling.

Green house effect is the major cause of global warming. In the troposphere level of atmosphere  there are  gases like co2,CFCS, methane and water vapour that aloe visible light and infrared radiation from the sun to reach the earth but do not allow heat from earth to escape out thereby increasing the temperature of the earth.

      Earth faced global warming and cooling in the past , long before human evolved   in the Earth .However the global warming occurring at present is found to be very rapid due to excess production of co2 .This is harmful to the natural ecosystem as they cannot adopt the fast occurring environment change thereby increasing the chance of species extinction.

       Global warming directly  effects the life and life cycle of organism, glaciers on mountains, heats up sea, melts polar ice, increases chance of forest fire, cause drought and dries up river, ponds and lakes.

    The melting of glaciers and polar ice increases sea level. Studies  have shown that the sea level has raised by 4-8 inches during the last 100 years. The rise of sea level brings coastal flooding that is dangerous to the island.

     Global warming heats the sea water and interferes with the circulation. The important circulation in the sea are: Arctic circulation, El Nino and LA Nina. They effect climate in most parts of the earth. High temperature can slow down Arctic circulation and increases the frequency and intensity of El Nino .

South America where as LA Nina causes the upwelling of cold  water in the west coast of south America and accumulation of warm water in the east coast of Asia near Indonesia . LA Nina

 cause rain and monsoon in India, Africa and North America.

Global warming has brought the following consequences:

a)            Late monsoon affecting crop production.

b)           Insecure supply of water

c)            Rapid melting of glaciers has endangered the existence of temperature lakes in high altitudes

d)           High possibility of forest fire

e)            Man as well as animals are forced to live under stress due to warm climate.

f)              Decreases the volume of water in the high altitude rivers and streams has threatened the life of the coldwater fishes and other aquatic organism.

g)           Land slides in many parts.

h)           Out break of diseases due to insufficient supply of water in hills.

i)              Excessive melting of ice has caused flooding in terai region ,affecting the life style of thousands of people and destroying land and crop.

             Control Measures:

    We must act responsibly against the global warming before it’s  too late.the following activities act against global warming:

a)            reduction in the use of fossil fuel

b)           increase hydropower to generate electricity

c)            maximum use of biogas and solar energy

d)           protecting and increasing the forest as they  absorbs co2, the main cause of global warming.