Green House Effect

GREEN HOUSE EFFECT

INTRODUCTION

In temperate countries some economically important plants that cannot grow outside at a very low temperature during the winter are grown in glass-walled & glass-roofed growth chambers (known as glass houses)exposed to sunlight. Glass houses are also used in sub tropiacal regions during winter months & relatively cold high altitude for high value horticultural annual crops including flowers on a cmmercial scale as well as for research work especially for breeding of new varieties

& crop physiological & pathological studies. Temperature within the glass house rises because of the glass of the roof & walls through it allows entry of sunlight with little obstruction,resist the escaping of the reflected light of longer wave-lengths rich in infra-red rays resulting in a heat built up. Such glass houses are called green housesas the light & heat within such houses prove very effective for profuse growth of green plants.

The property of trapping heat by carbon di oxide & other gases of the atmosphere is similar to the glass cover of green house that reasists the escaping of

heat radiated from inside of the house.As such, these atmospheric gases are called green house gases that resist the escaping of radiated heat from the earth by absorbing infra red rays & particularly reflecting the trapped heat back to earth\'s surface.this phenomenon is therefore called the green-house effect in wicch certain atmospheric gases act in a manner similar to the glass cover of glass house,as earth itself act as a green-house.

MAJOR GREEN HOUSE GASES

The major sources of green house gases are (i)CARBON DI OXIDE - It comes from burning of fossil fuels &from deforrestation. (ii)METHANE- It comes from paddy field,burning of wood,wetland etc. (iii)CHLOROFLURO CARBONS -which is populary known as CFC. It comes from air conditioning industry,foam packaging industries. (iv)NITROUS OXIDE-It comes from coal burning,motor veicheles,breakdown of chemial fertilizer,biomass burning.

Carbon-di-oxide is the major green-house gas responsible for more than 55% of the green-house-effect. Methane is responsible for 20%,CFC is responsible for 15% & NO is responsible for 5% of the green-house effect.

If the amount of carbon-di-oxide & other green-house gases would increase in the atmsphere ,the temperature on the surface of the earth & that of the layers of air adjuscent to the surface would increase,on the other hand global temperature would increase with the decrase in amount of the green house gases in the atmosphere.In fact the amount of all the green-house gase in the atmosphere is gradually increasing, as a result of which it is predicted that the global temperature would increase & there would be climatic changes on the earth resulting in adverse effects on the ecosystem of earth.We should therefore, well apprise ourselves of the green houses gases & or about the decrease or increase in the amounts of these gases in the atmosphere.

POSSIBLE EFFECTS OF INCREASED GREEN HOUSE GASAES

A possible direct effect on the of an increase in the amounts of green house gases in the atmosphere would be an increase in the average temperature of earth\'s surface & its adjuscent layers of air.But there is a difference of opinion among the scientists regarding the extent to which such temperature would increase & how rapidly such a change in global temperature would take place.

The predicted rise of global temperature may appear to be not too high, but if it actually increases as predicted ,the impact may be very high. It has been apprehended thet if the global temperature increases by only 3 degree celcius above the present temperature,a situation will arise which the living world did not face during the last 100000 years.

With a rise in global temperature there may be other consequential effects.Some possible effects are discussed below.

POSSIBLE EFFCTS ON CLIMATIC CONDITIONS

Emission of green house gases in the atmosphere in increasing rates may effect the climate to a large extent.

Due to an increase of average global temperature, water from various sourses on earth may evaporate more rapidly as a result of which the overall amount of rainfall may increase. But this phenomenon will not occur evenly in all parts of the world, in some regions specially in the tropical zones the summer may be prolonged,on the other hand in the north polar regions the temperature of the eaarth\'s surface & its adjacent air layers in the winter may be much higher compared to present situation.

POSSIBILITY OF RISING OF SEA LEVEL

If the global temperature increases the ice-caps & the glaciers of polar regions of the earth (Greenland, Antartica) may be melted partially, the floating ice on the water of the seas may also meltpartially or completely & due to an increase in temperature there may be an increase in volume of sea water as a result of which the level of sea water may rise.The problem of rehabilitation of the victimas of flood may become acute in many countries. Besides fertile agricultural lands of such areas being floodedwith suitable water may become unsuitable for cultivation badly effecting the production of crops.It is not difficult to presume that in case such a situation actually arises the worst sufferers will be the por countries in the third world.

With a rise of sea water level the low land areas of the deltas will face the maximum probability of being flooded with or being permanently immersed in sea water.Most of the low lying costal cities like Kolkata, Dhaka will be inundated. Low lying areas of different countries of the world will be flooded by salt water causing residential & food problem.

EFFECTS ON AGRICULTURAL PRODUCTION

It has been apprehended that due to intensive green house effect thee may be frequent droughts in summer in countries of middle latitudes of the north hemisphere, in that event production of crops may decrease in the northern parts of USA & in the present productive areas of the erstwhile U.S.S.R. On the other hand, the amount of carbon di oxide in the atmosphere being doubled & the average global temperature rising thereby,production of wheat may increase by 33% in the middle European regions or erstwhile USSR but the production of barley