1 Bismark Okaikwei Universität Bremen 9/01/08

2 Contents 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

3 Brief 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 FourierSvante Arrhenius Source:

4 The 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: use_effect.jpg

5 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)

6 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

7 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)

8 Enhaced greenhouse effect and climate 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

9 Alternative energy Solar power Wind power Water power

10 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:

11 Alternative energy Wind power (windmills): the power of the wind can be used to create electricity through large,wind-powered windmills called turbines Source:

12 Alternative 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

13 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

14 Thank you for your attention Happy New Year to you all!!!