IMPACTS OF HUMAN ACTIVTIES ON THE ATMOSPHERE

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IMPACTS OF HUMAN ACTIVTIES ON THE ATMOSPHERE
FONTAINE FX BREOT Jeremy PUECH Julien VIALA
Yannick
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I - DEFINITION
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The Earth's atmosphere is composed of 5
layers.The inhabitants of our planet live in the
Troposphere.
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• Earth's Atmosphere
• The Earth is surrounded by a blanket of air
  the atmosphere (over 560 kilometers i.e. 348
  miles)
• Life on Earth is supported by the atmosphere,
  solar energy, and our planet's magnetic fields.
• The atmosphere absorbs the energy from the Sun,
  recycles water and other chemicals, and works
  with the electrical and magnetic forces to
  provide a moderate climate.
• The atmosphere also protects us from high-energy
  radiation and the frigid vacuum of space.
• The envelope of gas surrounding the Earth changes
  from the ground up. Four distinct layers have
  been identified using thermal characteristics
  (temperature changes), chemical composition,
  movement, and density.

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COMPOSITION OF THE ATMOSPHERE
The atmosphere is primarily composed of -
Nitrogen (N2, 78)
- Oxygen
(O2, 21)
- Argon (Ar, 1)
A myriad of other very influential components are
also present which include the water (H2O, 0 -
7), "greenhouse" gases or Ozone (O3, 0 - 0.01),
Carbon Dioxide (CO2, 0.01-0.1),
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II CAUSES IMPACTS
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ROLE OF THE OZONE LAYER

• Ozone (O3) forms naturally in the upper
  atmosphere surrounding the Earth and protects
  life from the damaging ultraviolet light emitted
  by the sun.
• Ozone is destroyed by reactions with chlorine,
  bromine, nitrogen, hydrogen, and oxygen gases.
  Reactions with these gases typically occurs
  through catalytic processes. A catalytic reaction
  cycle is a set of chemical reactions which result
  in the destruction of many ozone molecules while
  the molecule that started the reaction is
  reformed to continue the process.

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PRINCIPAL EFFECT OF HUMAN ACTIVITIES CFCS
(chlorofluorocarbon)
When ultraviolet light waves (UV) strike CFC
(CFCl3) molecules in the upper atmosphere, a
carbon-chlorine bond breaks, producing a chlorine
(Cl) atom. The chlorine atom then reacts with an
ozone (O3) molecule breaking it apart and so
destroying the ozone. This forms an ordinary
oxygen molecule(O2) and a chlorine monoxide (ClO)
molecule. Then a free oxygen atom breaks up the
chlorine monoxide. The chlorine is free to repeat
the process of destroying more ozone molecules. A
single CFC molecule can destroy 100,000 ozone
molecules. CFC - chlorofluorocarbon it
contains chlorine, fluorine and carbon atoms.
UV radiation breaks oxygen molecules (O2) into
single oxygen atoms.
The most important reactions in the destruction
of ozone are
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GREENHOUSE EFFECT
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• The greenhouse effect, which is the rise of the
  Earths atmosphere temperature, is caused by sun
  rays reflected by the earth and by their
  absorption by greenhouse gas such as carbon
  dioxide. If the carbon dioxide concentration were
  to doubled, scientists estimated that temperature
  would rise by 1.3 C on earth surface.

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• The amount of carbon dioxide in the atmosphere
  has been increasing rapidly. Human activities are
  also releasing other "greenhouse" gases such as
  methane, ozone, and chlorofluorocarbons (CFCs),
  which intensify the heat-trapping properties of
  the atmosphere as a whole.

• Atmospheric concentrations of greenhouse gases
  are rising at unprecedented rates. Greenhouse gas
  emissions from developing countries are expected
  to increase rapidly. Large-scale climate changes
  may occur unless other climatic systems
  counteract the warming effect of the greenhouse
  gases.

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GLOBAL WARMING
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• Scientists have concluded that human activities
  are contributing to global warming by adding
  large amounts of heat-trapping gases to the
  atmosphere. Our fossil fuel use is the main
  source of these gases. Every time we drive a car,
  use electricity from coal-fired power plants, or
  heat our homes with oil or natural gas, we
  release carbon dioxide and other heat-trapping
  gases into the air. The second most important
  source of greenhouse gases is deforestation,
  mainly in the tropics, and other land-use changes.

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Effect of Land Use Change on Climate Greater than
Thought

• Land use changes may be at least as important as
  greenhouse gas emissions in accounting for
  climate change.
• Growing urban areas, deforestation and
  reforestation, agriculture and irrigation can
  have strong influences on regional temperatures,
  precipitation and large-scale atmospheric
  circulation.

• Pollution will continue to
• grow and contribute to
• Global Warming

• Concern is growing
• that atmospheric
• changes could bring on
• rapid, profound climatic
• changes.

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CONCLUSION

• To summarize, we can highlight the main reasons
  why we should
• take care of our atmosphere. Because one day if
  we keep going this way,
• human life on earth wont be possible anymore.
• Ozone surrounding the earth protects life from
  the damaging
• ultraviolet light emitted by the sun
• The greenhouse effect, which is the rise of the
  Earths atmosphere
• temperature, is caused by sun rays reflected by
  the earth and by their
• absorption by greenhouse gas such as carbon
  dioxide
• The second most important source of greenhouse
  gases is deforestation
• Atmospheric concentrations of greenhouse gases
  are rising at
• unprecedented rates.
• And then, we hope that responses and solutions
  can be applied to these
• problems that are economically feasible.