11

Bismark OkaikweiBismark OkaikweiUniversität BremenUniversität Bremen

9/01/089/01/08

22

ContentsContents

• 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

33

Brief history on greenhouse effectBrief history on greenhouse effect

• It was discovered by Joseph Fourier in 1824

• But it was first investigated quantitatively by Svante Arrhenius in 1896

• He claimed that fossil fuel combustion may

eventually result in enhanced global warming

• 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

• Arrhenius suggested that a doubling of carbon dioxide concentration would lead to a 5ºC temperature rise

Joseph Fourier Svante Arrhenius

Source: www.famoussceientists.com

44

The basic mechanismThe basic mechanism

• Natural gases in the earth`s atmosphere reduce the amount of heat escaping the earth into the atmosphere

• Intensity of infrared radiation increases with increasing temperature

• Average earth‘s temperature is 15ºC

Source: http://www.environment.sa.gov.au/sustainability/images/greenh

ouse_effect.jpg

55

What are greenhouse gases?What are greenhouse gases?

• Water vapour (H2O)

• 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%).

• 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%).

• Nitrous Oxide (N2O): Its amount in the atmosphere is about 15% higher now than 200 years ago.

• Halocarbons: These greenhouse gases have been reduced since the phasing out of chlorofluorocarbons (CFCs) to protect the ozone layer.

• Ozone (O3)

66

What makes them greenhouse gases?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

77

How do we make greenhouse gases?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)

88

Enhaced greenhouse effect and Enhaced greenhouse effect and

climate changeclimate change • Melting of polar ice and oceanic expansion.This results in flooding of coastal

areas,swamps,wetlands and river deltas

• Increase in number and severity of tropical storms and cyclones

• Evaporation of water supplies causing drinking water scarcity

• Flooding and erosion of agricultural plots.This damages crops and soils and decreases harvest

• More extreme weather,causing hotter and drier summer and colder winters

99

Alternative energyAlternative energy

• Solar power

• Wind power

• Water power

1010

Alternative energyAlternative 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

1111

Alternative energyAlternative energy

• 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

1212

Alternative energyAlternative energy

• 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

1313

SummarySummary

• 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

1414

Thank you for your attentionThank you for your attention

Happy New Year to you all!!!