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Greenhouse Effect and Global Warming - DOC

VIEWS: 60 PAGES: 8

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									                                    GROUP A (APRIL)

                  Greenhouse Effect and Global Warming

              The Earth is wrapped in a blanket of air called the 'atmosphere', which is made up of
              several layers of gases. The sun is much hotter than the Earth and it gives off rays of
              heat (radiation) that travel through the atmosphere and reach the Earth. The rays of the
              sun warm the Earth, and heat from the Earth then travels back into the atmosphere. The
              gases in the atmosphere prevent some of the heat from
              escaping into space. These gases are called greenhouse gases
              and the natural process between the sun, the atmosphere and
              the Earth is called the 'Greenhouse Effect', because it works
the same way as a greenhouse. The windows of a greenhouse play the same
role as the gases in the atmosphere, keeping some of the heat inside the
greenhouse.


THE NATURAL GREENHOUSE EFFECT

We know that the atmosphere has a number of gases, often in tiny amounts,
which trap the heat given out by the Earth. To make sure that the Earth's
temperature remains constant, the balance of these gases in the atmosphere
must not be upset.




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The GREENHOUSE GASES are very important and are mainly:
    Water vapour- occurs naturally in the atmosphere.
    Carbon dioxide- produced naturally when people and animals breathe. Plants and trees absorb
       carbon dioxide to live. Volcanoes also produce this gas.
    Methane- comes from cattle as they digest their food. The gas also comes from fields where
       rice is grown in paddy fields.
    Nitrous oxide- when plants die and rot, nitrous oxide is produced.
    Ozone- occurs naturally in the atmosphere.


THE GREENHOUSE EFFECT CAUSED BY MAN

Some of the activities of human also produce greenhouse gases. These gases
keep increasing in the atmosphere. Burning fossil fuels such as coal, oil and
natural gas releases carbon dioxide into the atmosphere. Cutting down and
burning trees also produces a lot of carbon dioxide to the environment.

A group of greenhouse gases called the chlorofluorocarbons (CFCs) have
been used in aerosols, such as hairspray cans, fridges and in making foam
                             plastics. They are found in small amounts in the
                             atmosphere. They are dangerous greenhouse
                             gases because a small amount of it can trap large
                             amounts of heat. Because there are more and
                             more greenhouse gases in the atmosphere, more
                             heat is trapped which makes the Earth warmer.
                             This is known as GLOBAL WARMING.

                    A lot of scientists agree that man's activities are making the natural greenhouse
                    effect stronger. If we carry on polluting the atmosphere with greenhouse gases, it
                    will have very dangerous effects on the Earth.




THE EFFECTS

With more heat trapped on Earth, the planet will become warmer, which
means the weather all over Earth will change. For example, summers will get
hotter, and winters too. This may seem a good idea, but the conditions we are

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living in are perfect for life, and a large rise in temperature could be terrible for us and for any other
living thing on Earth.

The Weather

In future, the winter and summer temperatures will increase and the
weather will be warmer. In winter it may also rain more but in summer it
may become drier. In other parts of the world, the effects will be
different, some places will become drier and others will be wetter.
Although most areas will be warmer, some areas will become cooler.
There may be many storms, floods and drought, but we do not know
                           which areas of the world will be affected. All
                           over the world, these weather changes will
                           affect the kind of crop that can be grown.
                           Plants, animals and even people may find it
                           difficult to survive in different conditions.

Sea Levels

Higher temperatures will make the water of the seas and oceans expand. Ice melting in the Antarctic
                          and Greenland will flow into the sea. All over the world, sea levels may rise,
                          perhaps by as much as 20 to 40 cm, by the beginning of the next century.
                          Higher sea levels will threaten the low-lying coastal areas of the world, such
                          as the Netherlands, Bangladesh and low lying
                          parts of India. Throughout the world, millions
                          of people and areas of land will be at danger
                         from flooding. Many people will have to leave
their homes and large areas of farmland will be ruined because of floods.

Farming

The changes in the weather will affect the types of crops grown in different
                           parts of the world. Some crops, such as wheat and
                           rice grow better in higher temperatures, but other
                           plants, such as maize and sugarcane do not. Changes
                           in the amount of rainfall will also affect how many
                           plants grow. The effect of a change in the weather on
                           plant growth may lead to some countries not having
                           enough food and many people could suffer from hunger.

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Water

                             Everywhere in the world, there is a big demand
                             for water and in many regions, such as the Sahara
                             desert in Africa and Thar desert in India; there is
                             not enough water for the people. Changes in the
weather will bring more rain in some countries, but others will have less rain.

IN DANGER!

Plants & Animals

                              It has taken million of years for life to
                              become used to the conditions on Earth.
                              As weather and temperature changes, the
                              homes of plants and animals will be
                              affected all over the world. For example,
                              polar bears and seals will have to find new land for hunting and living,
                              if the ice in the Arctic melts.

                             Many animals and plants may not be able to cope with these changes
                             and could die. This could cause the loss of some animal and plant
                             species in certain areas of the world or everywhere on Earth resulting to
                             the decline of Natural Resources.




People

The changes in climate will affect everyone, but some populations will be at
                       greater risk. For example, countries whose coastal
                       regions have a large population, such as Egypt and
                       China, may see whole populations move inland to
                       avoid flood risk areas. The effect on people will
                       depend on how well we can adapt to the changes
                       and how much we can do to reduce climate change
                       in the world.



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                                           OZONE HOLE
                          We have already discussed in the beginning that the atmosphere is made up
                          of several layers. About 19-30 kilometers above the Earth is a layer of gas
                          called ozone, which is a form of oxygen. Ozone is produced naturally in the
                          atmosphere.


                          WHY DO WE HAVE AN OZONE LAYER?

                          The ozone layer is very important because it stops many
of the sun's 'ultra-violet rays' (UV rays) getting through to the Earth - these are the
rays that cause our skin to tan. Too much UV can cause skin cancer and will also
harm all plants and animals. Life on Earth could not exist without the protective
shield of the ozone layer.

WHAT IS THE OZONE HOLE?

                         Every spring, a hole as big as the USA develops in the ozone layer over
                         Antarctica, in the South Pole. A smaller hole develops
                         each year over the Arctic, at the North Pole. And there
                         are signs that the ozone layer is getting thinner all over
                         the planet.

                      The loss of the ozone layer occurs when more ozone is
being destroyed by human activities than nature is creating.

WHAT CAUSES THE OZONE HOLE?

One group of gases is particularly likely to damage the ozone layer. These gases are called CFCs,
                          Chloro-Fluoro-Carbons. CFCs are used in some spray cans to force the
                          contents out of the can. They are also used in
                          refrigerators, air conditioning systems and some fire
                          extinguishers. They are used because they are not
                          poisonous and do not catch fire. Most countries have now
                          stopped using new CFCs that can be released into the
                          atmosphere, but many scientists believe that we must
                          stop using old ones as well.




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THE OZONE HOLE AND OUR HEALTH

                    The ozone layer is like a sunscreen, and a thinning of it would mean that more
                    ultra-violet rays would be reaching us.

                    Too many UV rays would cause more sunburn, and because
                    sunburn causes skin cancer, this too would increase deaths.

                    These UV rays are also dangerous for our eyes and could
                   cause an increase in people becoming blind. That is why sun
cream and sunglasses are very important.

THE OZONE HOLE ON ANIMALS AND PLANTS

                      UV rays can go through water and end up killing
                      small water animals or plants, called 'plankton' which
                      form the base of the food chain in oceans and seas.
                      Whales and other fishes have plankton as their main
                      food, and if plankton dies because of these UV rays,
                      whales will start dying too, because they will not
have anything to eat. Large amounts of UV rays could damage all green
plants. If the ozone layer keeps getting thinner, there could be fewer and fewer plants on Earth, and
then there would be less food in the whole world.

THE TWO-FACED OZONE GAS

                    Ozone found between 19 and 30 kilometers high in the atmosphere is one of the
                    reasons why we are alive on Earth.

                    But when the gas ozone is found lower down where we can
                    breathe it in, it becomes very dangerous for our health. This
                    ozone is caused by a reaction between air pollution and sunlight
                    and can cause modern-day smog. This is different to the smog
                    that formed in the early 20th century from smoke and fog.




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                                      Our Responsibilities


                      What can you do:

                      There are many things we can do to help reduce air pollution and global
                      warming.

                      Use buses and trains instead of cars, as they can carry a
                      lot more people in one journey. This cut down the
                      amount of pollution produced and also saves the fuel.




                         Walking or cycling whenever you can, will be better
                         as it does not create any pollution. It will also be
                         good for your body, as regular exercise will keep
                         you fit and healthy.

                          If your parents use the car, ask them to avoid using
                          it for very short journeys if possible, as this creates
                          unnecessary pollution. Try to encourage them to share their journeys with
                          other people, for example when they go to work or go shopping. Also
                          encourage them to drive more slowly as this produces less pollution and less
                          carbon dioxide.

                        Energy is produced to generate electricity and to keep
                        us warm. Most energy is produced by the burning of
                        fossil fuels, like coal, oil and gas, which release
                        carbon dioxide, a greenhouse gas. Fuel burnt in our
                        cars also releases carbon dioxide. As an individual,
                        you do not have a lot of control on how your energy
                        is produced. However, you can control the way in
which you use that energy. Using less energy means less of it needs to be
produced. So less carbon dioxide is released into the atmosphere.

We can also help prevent pollution from our own homes which may
contribute to acid rain and poor air quality, and increases emissions of carbon
dioxide in the atmosphere. Turning off lights when they are not needed and
not wasting electricity will reduce the demand for energy. Less electricity will

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need to be produced and so less coal, oil and gas will have to be burnt in power stations, which means
less air pollution and less carbon dioxide!

Pollution formed indoors can be reduced by ensuring that all gas appliances are working correctly.
                             Good ventilation will improve indoor air quality by dispersing
                             biological pollutants like dust mite, and other pollutants such as
                             cigarette smoke. Most of the rubbish we throw
                             away can be recycled, such as glass bottles
                             and jars, steel and aluminium cans, plastic
                             bottles and waste paper.

                       Recycling used materials uses less energy than
                       making new ones.

                        Composting fruit and vegetable waste reduces the amount of rubbish buried at
                       rubbish dumps.




                        What are the Governments doing?

                        Governments throughout the world have already taken action for these
                        different environmental problems (i.e. Acid Rain, Air Quality, Ozone Hole,
                        and Global Warming). In their plans they hope to reduce
                        the amount of emissions of greenhouse gases produced
                        by man. About half of the greenhouse effect is caused by
                        our use of energy, especially from fossil fuels. Other
                          sources of energy could be used which do not emit
                          carbon dioxide, e.g. wind power, solar (sun power)
                          and wave power. In the home and at school, we must
                          learn to use energy efficiently and not waste it.



                          Although adults do many things to help stop global warming, kids
                           can do just as much. Kids can’t do hard things like making a law,
                         but we can do easier things like not watching as much TV. You can
                           listen to your parents when they say, turn off your lights or go
                         play outside. Listening to them and actually trying to help can help
                                          you, your environment, and the world.


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