Global Warming

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Introduction
A Global Warning: Global Warming|
The world is warming dangerously. It depends either on the natural causes or the artificial causes like human based greenhouse gases. This affects both the vegetation and zoological environment and also the human| life. Its effects are gradually increasing every year.The purposes of our project are:·To investigate the causes and the effects of global warming and to present the results of our survey.·To attract attention on the solution proposals about global warming and become more effective on this issue.|

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Causes of Global Warming|
Weather conditions seen in a long period of time are called 'climate'. The world passed approximately 250 thousand million years of warm periodsand four major cold periods in the last billion years.|

50 million years ago, the world entered the fourth cold period. In this era which lasted 100 thousand years, there were warm periods that lasted 10 thousand years. In this century, we are living one of these warm periods. The heat decrease started 4 thousand years ago and the world should now tend to cool down, but it did not in the last 150 years.The main cause of global warming is the sun and the human based greenhouse effect.|

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Natural Causes
Effect of the Sun|
Paal Brekke - ESA scientist - declared that; scientists specialised on climate are researching Sun's circular movements and the change of its brightness. The Sun's magnetic field and the Sun wind that appears as| protons and electrons are creating a shield against the cosmic rays. The strength of the shield changes depending on the different activities of the Sun and the shield is unable to prevent the cosmic rayspermanently.The increase of these cosmic rays directly increases the number of clouds in the sky. It is changing the ratio of radiation created by the sun. The changing ratio is causing the global warming.| a| |

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The ultraviolet is affecting the ozone layer and the whole atmosphere, because it is creating chemical reactions.|

Earth's Precision Movement Effect|
In 1930, a Serbian scientist, Milutin Milankovich, emphasized that; world's orbit became pressed down every 95 thousand years. He also declared that there was a circular slide in every 41 thousand years and a circular| deviation in every 231 000 years in world axis. Nowadays, most of the scientists accept that, world's movement changements cause temporarily cold weather periods. During these periods, every 100 thousand years there are some hot eras which last about 10 thousand years. That is one of the reasons of the world's increasing temperature.|

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El Nino's Effect|
The movement of El Niño is defined as a "warm event of south fluctuation" which causes Tropical East Pacific Ocean's surface temperatures' to raise about 2-5ºC (35-45ºF) particularly in 1997-1998. The strongest El Niño in| 1998 is the main factor of the high temperature in that year.| a|

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Artificial Causes

Fossil Fuels|
Coal, petroleum and natural gas provide %75 of the world's energy need today. Fossil fuels which have carbon and hydrogen elements in their structures are formed in long processes, but consumed very fast. These| fuels are gathered in certain parts of the world; and it is impossible to get them in ¾ of the world, and technically it is very expensive for the other ½. These disadvantages put fossil fuels in non-recycled, limited fuels' class.| a|

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The Occurence of The Greenhouse Effect|
The ozone layer and gases present in the atmosphere absorb some of the sunrays. A part of these are reflected from lithosphere and others are reflected from clouds. While the rays that hit the earth surface reflect back,| water steam and other gases keep them. These rays warm up the earth but surface and troposphere get warmer than usual. This event is similar to the greenhouse effect that warms up the earth with sunrays and it is called natural...
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