Transcript Bismark Okaikwei PEP Student 19/11/07 - pep

Bismark Okaikwei
Universität Bremen
9/01/08
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Contents
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Brief history on greenhouse effect
The basic mechanism
What are greenhouse gases?
What makes them greenhouse gases?
How do we make greenhouse gases?
Enhanced greenhouse effect and climate change
Alternative energy
Summary
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Brief history on greenhouse effect
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It was discovered by Joseph Fourier in
1824
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But it was first investigated quantitatively
by Svante Arrhenius in 1896
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He claimed that fossil fuel combustion
may eventually result in enhanced global
warming
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He found that the average surface
temperature of the earth is about 15ºC
because of the infrared absorption
capacity of water vapor and carbon
dioxide
Joseph Fourier
Svante Arrhenius
Source: www.famoussceientists.com
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Arrhenius suggested that a doubling of
carbon dioxide concentration would lead
to a 5ºC temperature rise
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The basic mechanism
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Natural gases in the earth`s
atmosphere reduce the amount
of heat escaping the earth into
the atmosphere
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Intensity of infrared radiation
increases with increasing
temperature
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Average earth‘s temperature is
15ºC
Source:
http://www.environment.sa.gov.au/sustainability/images/greenho
use_effect.jpg
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What are greenhouse gases?
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Water vapour (H2O)
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Carbon dioxide (CO2): The amount in the atmosphere is about 30%
higher now than 200 years ago. It is the biggest contributor to the
enhanced greenhouse effect (about 70%).
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Methane (CH4): The amount in the atmosphere is about 145% higher
now than 200 years ago. It is the second biggest contributor to the
enhanced greenhouse effect (20%).
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Nitrous Oxide (N2O): Its amount in the atmosphere is about 15% higher
now than 200 years ago.
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Halocarbons: These greenhouse gases have been reduced since the
phasing out of chlorofluorocarbons (CFCs) to protect the ozone layer.
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Ozone (O3)
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What makes them greenhouse gases?
• They can vibrate in the infrared region because of their symmetry
and these vibrations create transient charge separation
• With such dipole moment,they can absorb and emit infrared
radiation
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How do we make greenhouse gases?
• Burning of fossil fuels for energy (for electricity and fuel for
transport) generates the most greenhouse gases
• Removing and burning vegetation since plants serve as
greenhouse gas "sinks“
• Farming (animals particularly cattle and sheep produce methane
and some fertilizers produce nitrous oxide)
• Waste breakdown
• Industry (cement and aluminium production)
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Enhaced greenhouse effect and
climate change
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Melting of polar ice and oceanic expansion.This results in flooding of coastal
areas,swamps,wetlands and river deltas
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Increase in number and severity of tropical storms and cyclones
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Evaporation of water supplies causing drinking water scarcity
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Flooding and erosion of agricultural plots.This damages crops and soils and
decreases harvest
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More extreme weather,causing hotter and drier summer and colder winters
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Alternative energy
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Solar power
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Wind power
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Water power
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Alternative energy
• Solar power (energy from the
sun): new photovoltaic cells
filled with silicon,however are
able to take the sun‘s energy
and transform it into electricity
Source: www.daviddarling.info
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Alternative energy
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Wind power (windmills): the
power of the wind can be used
to create electricity through
large,wind-powered windmills
called turbines
Source: www.powerhousetv.com
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Alternative energy
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Water power: two main ways to use water to create electricity are
hydro-electricity which relies on vast volumes of water flowing
down pipes and spining giant turbines and then tidal changes and
waves
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Summary
• The greenhouse effect describes how natural gases in the
earth‘s atmosphere reduce the amount of heat escaping from
the earth into the atmosphere
• The greenhouse gases are water vapor, carbon dioxide, nitrous
oxide, CFCs,ozone and methane
• These gases are produced from the burning of fossil fuels,
removing and burning vegetation, farming, waste breakdown
and industry
• Enhanced greenhouse effect causes global warming
• Alternative energy include solar, wind and water power
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Thank you for your attention
Happy New Year to you all!!!
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