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Greenhouse Effect and Thinning of

the Ozone Layer

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The Greenhouse Effect

Energy from the sun reaches the Earth throughradiation. Some of this radiation is absorbed by theearth to warm the surfaces of sea and land.

As the earth is warmed, heat in the form of infrared

radiation is radiated back into space However much of this radiation is prevented from

escaping into space by greenhouse gases such ascarbon dioxide (CO2) methane (CH4), nitrous oxide

(N2O) and chlorofluorocarbons (CFCs) As a result the infrared radiation is radiated back to

the earths surface, warming the Earth further.

http://environment.nationalgeographic.com/environment/global-warming/gw-overview-interactive/

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This phenomenon is known as the greenhouse

effect. It is similar to a greenhouse used infarming in countries which experience

temperate climates. The glass of a greenhouse

allows light to enter but retards the loss ofheat. The heat is used to keep the soil and air

warm in the greenhouse.

An increase in greenhouse gases is caused by

human activities, mainly

and .

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Generally Suns Rays the Earth

heat

Heat by

greenhouse gases Temperature

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Effect of global warming Melting of polar ice and glaciers causing a rise in sea

level

Floods in low-lying countries Change in wind directions and weather patterns

Increase of droughts

Decline in the yield of crops due to dry and infertilesoil

Spread of pests and disease-carrying vectors to newareas increases the outbreak of diseases

Intense rains in some regions

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Step to reduce global warming Reduce the burning of fossil fuels

Reduce deforestation

Reduce or stop open burning

Practice replanting of trees

Develop other sources of energy such as solar,wind and geothermal energy

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Thinning of the Ozone Layer

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Ozone layer is present in the stratosphere

which approximately 12 - 25 kilometers abovethe Earth;s surface.

This ozone layer shields the earth from the

harmful effects of ultraviolet (UV) radiation. High concentrations of ozone (O3) in the

ozone layer can absorb large quantities of

ultraviolet radiation

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Ozone, although a form of oxygen, once depleted willnot be replenished naturally.

The main cause ozone depletion is the increasinglevel of chlorofluorocarbons (CFCs) in theatmosphere.

The use of CFCs as coolants in air conditioners andrefrigerators, as propellants in aerosol cans, as solventin the electronics industry and as foaming agents inthe making of polystyrene boxes has released largeamounts of CFCs into the atmosphere

CFCs are unreactive and can remain unchanged forover 100 years

UV radiation breaks down CFCs. Releasing chlorineradicals which destroy ozone in a chain reaction

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Exposure to UV radiation effects Human health

- Skin cancer or melanoma

- Eye damage such as cataract

- Lowering of bodys immune system

Plants

- damage of leaf cells and chlorophyll, reducing photosynthesis

- Decrease in nutrient content and crop yields

- Killing phytoplanktons

The Environment

- Increase in surrounding temperature

- Change in wind directions

- Climatic changes

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