Global warming:the causes & effects

Global Warming:The causes & effects

The earth is surrounded by air which acts like a layer of insulation,keeping heat in,just as in a green house.Two gases carbon dioxide and methane ,are very good at keeping the heat in-this is why they are called green house gases_they have been very useful in making the earth warm enough for human life.But the amount of carbon dioxide and methane in the air are increasing..The increased green house effect is causing  the earth to slowly warm up.This is called global warming.

Causes:

(a) Heat radiation from the sun passes through the atmosphere and hits the earth surface.

(b) Most of the heat is absorbed by the earth and warms it up.

(c) Some of the heat is reflected back.Most of this heat escapes into space.

(d) Some of the reflected heat is trapped by green houses gases and reflected back to earth ,causing global warming.

The increase in carbon dioxide is mainly due to burning more fossil fuels,but all over the world trees have been cut down to make space for farming and building home.Fewer trees means less photosynthesis .Less photosynthesis mean less carbon dioxide is taken from the air.Methane comes from marshy areas,such as where rice is grown ,from cattle as they belch and break wind!More rice and more cattle mean more methane

Effects:

In the last 100 years the temperature at the earth's surface has risen by about 0.5 centigrade.That may not seem too much,but if these temperature rises continue ,they will cause huge change.There are just some predictions made by the scientist studying global warming.

(1) More ice in the Arctic and Antarctic will melt.This is happening already sea level will rise as the ice cap melts.low lying areas of the world will flood.Some pacific islands will be drowned.

(2) Weather patterns will change.Some areas will suffer droughts,and crops will fail.People will starve.There will be more refugees.

(3) Other regions will have  more frequent storms and floods.

(40 Mosquitoes and other insects which live in warm places will spread to new areas,possibly carrying diseases.

The poorest countries will be least able to cope with these changes,so will suffer most.This is ironic since they burn least fossil fuels.Scientist have been reporting the link between fossil fuel production and global warming for a long time.Carbon dioxide levels in the atmosphere have been carefully monitored since 1957.Samples of air trapped  in ice caps provided information about carbon dioxide levels before 1957.The amount of carbon dioxide in the atmosphere is rising because of the increased amount of fossil fuels we are burning.It has been rising since the industrial revolution- a time during the 18th century in Europe when the large scale fossil fuels began.The average global temperature shows the same pattern .Global warming is happening.Most scientist agree that carbon dioxide is the main cause. 

Unusual,some time catastrophic,climatic events such as severe droughts,are forcing the world's government to pay more attention to the dangers of global warming.However many are not willing to take the drastic steps of cutting back on the use of fossil fuels especially in the USA which is the world's main carbon dioxide producer.Fossil fuel keep a country's economy going.Factories,transport system,and power stations all rely on a steady supply of fuel.Larger taxes could be put on fuels to encourage people  to use less,but this could seriously harm the economy-and politicians could lose votes.Unless there are some serious alternative to fossil fuels,few government will take the risk of losing votes and power.

At the same time , many people do not really think climate change is a problem.They still want to drive around in big cars,run lots of electrical appliances and fly around the world on business and holidays.Until we all accept that global warming is a problem ,nothing significant is going to happen to save our planet.Our current level of carbon dioxide  and methane production cannot continue without serious harm to our planet.Pressure is on to develop,clean,renewable sources of energy,such as wind and solar power,as quickly as possible.         

Conclusion:

The increasing use of fossil fuels and the deforestation have led to an increase in the level of carbon dioxide in the air.Gases like water vapor .methane,and CFC also act in a similar way in the atmosphere.These gases are called green house gases.Molecules of these gases absorb much of the infra red radiation given out by the surface of earth.This increases their kinetic energy .So the atmosphere becomes hotter.The higher the concentration of green gases in the air,the green is the green house effect,the greater will be the increase in temperature.The green house effect is a natural phenomenon of the energy distribution mechanism of the earth.However certain human activity is threatening to cause a significant increase in the green house effect.Global warming is due to an up set in the natural balance of the concentration of green house gases in the atmosphere.If the global warming continue then,temperature of earth will increase,the earth climate may change,polar ice may melt,and cause significant increase in sea level,so the atmosphere become hotter.Green houses are built from glass or transparent ploymer films.Such light can pass through these materials and is used by the plants for photosynthesis.The plants radiate some energy in the form of infrared or heat radiation which cannot pass through these materials and is reflected back.As a result the atmosphere in the green house becomes hot enough to promote plant growth.The temperature in side the green house can be 10 degree to 15 degree higher than out side.