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1.Carbon Dioxide (CO2) 2.Ozone (O3) 3.Methane (CH4) 4.CFC’s (Freons F11 & F12) 5.Water vapour (H2O) 6.Nitrous Oxides (NOx) 7.Ethane (CH3CH3) Where do they come from? •Most of Greenhouse gases have resulted from burning of fossil fuels. Everything from power stations, motor vehicles, refrigerators, and factory emissions •However, CO2 also results from deforestation which releases carbon locked in soil when trees are felled. •CH4 is released from agriculture such as sheep, cattle and manures and places such as tips, sewage treatment plants and mines. Fossil Fuel contributions Due to nature of carbon to hydrogen ratio, different fossil fuels emit different levels of CO2.
Fossil FuelCarbon to Hydrogen Ratio CoalApprox. 1:1 Oil Approx. 1:2 Natural GasApprox. 1:4
Table 1: approximate carbon to Hydrogen ratio for various fossil fuels
•Hence combustion of coal produces twice CO2 of natural gas CO2 Levels in atmosphere
Pre Industrial Revolution270 ppm 1988345 ppm Today>355 ppm
Table 2: Levels of CO2 in ppm (parts per million)
•By measuring bubbles of gases trapped in polar ice, scientists have shown that amount of CO2 in atmosphere prior to Industrial Revolution was about 270 parts per million (ppm). •A special monitoring station established atop from mountain Mauna Loa in Hawaiian Islands showed that by 1957 CO2 levels in atmosphere to 315 ppm, an increase of 17%. •By 1988, it had passed 345 ppm. A rise in 31 years of another 11%. An increased total of about 30% since start of Industrial Revolution. •Expert’s further forecast that CO2 will reach a level of 500-700 ppm by year 2050, a doubling inside 200 years. Percentage Contribution of Greenhouse gases to Greenhouse Effect
CO255% CFC (F-11/F-12)*17% CH415% NO26% Other7%
Table 3: Percentage contribution of various Greenhouse Gases
* Please note that CFCs have been phased out since mid-nineties
To stablise atmospheric concentration of various gases at present day levels, following reductions would be required instantly
CO260% CH415-20% NO270-80% CFC (F-11)*70-75% CFC (F-12)*75-85%
Table 4: Reductions of Greenhouse Gases required to stablise atmospheric concentrations Remaining Scientific Uncertainty No argument that increasing concentrations of heat trapping gases will lead to an increase in average temperatures world-wide. However there is an argument about extent in some cases of various positive and negative effects.
1.Uncertainty in effects of clouds Cumulus- negative cooling effect reflect incoming sunlight High Altitude clouds- positive effect by trapping infra-red radiation from earth •This uncertainty explains variation in temperatures from 1.5oC to 4.5oC. 2.Combustion of fossil fuels e.g. coal to sulphur dioxide (SO2) has cooling effect. 3.Variations in sun’s output are responsible for temperature increases. 4.Ocean levels will naturally increase due to thermal expansion of surface ocean water and melting of glaciers. •An increase in temperature will lead to increased precipitation, which will increase ice thickness at poles, thus reducing sea level. 5.Natural regional climatic changes, such as deforestation and bushfires, as opposed to global changes. Policies for Greenhouse Emission Reduction Problems 1.Different countries emit vastly different CO2 levels per capita 2.Countries have very different per capita incomes 3.Very difficult to work out warming potential for each Greenhouse Gas in terms of CO2 equivalent. 4.Emissions of gases from various countries are not known with certainty Policies 1.Each country can reduce by same percentage •Existing emission levels are uneven per capita are taken as standard •Poor countries want to increase fossil fuel usage
2.Each country gets same emission quotas on a per capita basis. These countries sell quotas to rich countries.
3.Rich countries could reduce emissions by 20% with no reductions required by poor countries.
•Not all rich countries have high emissions of CO2, and not all poor countries are low emitters because of deforestation.
4.Assume Australia which is high income and high Greenhouse Gas emitter per capita is required to reduce emissions by 20%. •How should it be reduced? By: a)each state? b)each industry section? Some methods of reducing CO2 emissions that have negative impact on our lives •Better managing of natural resource; •Reducing waste in manufacturing; •Find alternative end uses for waste (recycle and reuse); •Buying less junks and goods that we don’t need (In Australia, estimated to be worth AUD$10 billion per annum); •Buying quality goods that don’t need replacing as often; •Recycling more (e.g. it takes about 8 times more energy to convert bauxite to aluminium than it does to recycle it) •Reduced use of motor vehicles; •Increased use of public transport; •More efficient lighting, heating and cooling; •Better insulation; •Less reliance on electricity and electrical goods and machines; •More efficient electrical appliances; •More efficient cars; •Alternative technologies from natural sources such as wind, thermal and tidal; •Converting landfills and sewage plants into methane plants; •Bio-fuels such as bio-diesel, methanol and ethanol production from organic sources •Reduce large scale deforestation and land clearing; •Increase tree planting; •More efficient agriculture including No till and Conservation agriculture methods; •Organic farming.
Tobi Nagy runs SDS Consulting which is a small business enterprise development practice which focuses on developing enterprises with sustainable business principles and practices. His website can be viewed at www.sustainable-development.net