Past paper discussions
Marjorie Henry, Contributor

I started the discussion of question 10, taken from the June 2008 paper in the last lesson. I have already done subsections (a) and (b).

Here now is part (c) of the question.

(c) For any TWO greenhouse gases, describe how the concentration of EACH increases in the atmosphere. (4 marks)

As a guideline in answering, you should first name the greenhouse gas and then state something that is done to increase that gas in the atmosphere. I will share with you the information on some of the main greenhouse gases.

Carbon dioxide

Carbon dioxide forms the largest proportion of greenhouse gases in the atmosphere and is the most important greenhouse gas. It is generated when fossil fuels are burnt, for example, the burning of coal to generate electricity. For every kilogramme of fossil fuel burnt, about three kilogrammes of carbon dioxide are produced.

It is estimated that approximately six to seven billion metric tons of fossil fuels are burnt each year. This means that 18 to 21 billion metric tons of carbon are added to the atmosphere each year.

It has been estimated that the amount of carbon dioxide is increasing at the rate of 0.2-0.7 per cent per year. Fossil fuels include oil, coal and natural gas. Other sources where carbon dioxide is generated in large amounts are from the flaring of natural gas, deforestation for agriculture, and the manufacturing of cement.

Carbon monoxide is emitted from motor vehicles, and some factories, like the aluminium plant, are also responsible for the concentration of this gas in the atmosphere.

Methane is a natural by-product of bacterial actions in the stomachs of livestock as well as in the water of rice fields. It is produced when natural fermentation takes place. In keeping with the effort to increase food supply, more livestock is kept and more rice is grown. As a result, the amount of methane released into the atmosphere has increased. Other sources of methane include garbage in landfill sites, coal mining, sewage plants, leaks from natural gas lines and biomass.

Man-made chemicals

Chlorofluorocarbons (CFCs) are man-made chemicals used in the manufacturing of aerosols, refrigerators and air conditioners. They are also used for packaging foam and insulation. They take a long time to break down in the atmosphere.

Nitrogen oxide is emitted through the burning of fuels and the use of chemical fertilisers containing nitrogen. The nitrogen in the fertilisers reacts with the soil and form nitrous oxide. Nitrous oxide is also produced when fossil fuels are burnt from combustion from factories and (especially) high-performance motor cars. Once released into the atmosphere, it takes a long time to break down, just like CFCs.

Sulphur dioxide is produced from coal-burning power stations, heating of buildings, cooking gases, factories and transportation.

Reducing the production of greenhouse gases

I now go to part (d) of the question.

(d) Using examples from a developed country, explain how TWO measures can reduce the production of greenhouse gases.

The geography syllabus has a list of developed countries from which you can choose to study. Just in case you do not yet have a syllabus of your own to refer to, here are the countries:

Canada

United States

Japan

Netherlands

France

United Kingdom

The Caribbean Environment by Mark Wilson, one of the recommended textbooks, has information on the measures implemented in the Netherlands to reduce the production of greenhouse gases. Here is that information.

• Manufacturing: New fuel-efficient equipment at the country's two aluminium smelters.
• Energy companies: More efficient fuel use in generating stations with some switching from coal to natural gas. Renewable energy sources will increase from 1.5 per cent of energy use in 1999 to 5 per cent in 2010 and 10 per cent by 2020. Electricity will be produced by burning municipal waste from wind energy and by families who install photovoltaic roof panels to generate electricity with solar power.
• Traffic: Speed limits will be tighter. Families will be encouraged to use bicycles for journeys of less than 7.5 km (which would also bring health benefits). The tax system will encourage fuel-efficient vehicles.
• Households: There will be increased use of energy-saving appliances. Better insulation of new homes will reduce heating energy use.
• Planting trees: New forests on 750 sq km by 2020. This will also have recreational and wildlife benefits.

(Sources: CSEC New Integrated Geography by Sheldon G. Bleasdell et al; Geography for CSEC by Jeanette Ottley et al; The Caribbean Environment by Mark Wilson.)

Edwin Allen's Amoy Blake (left) powers away from the field after receving the baton from her teammate, Gayon Evans (right), to win the girls' Class One 4x100m in 45.60 ahead of Holmwood Technical (46.44) at the Central Hurdles and Relays Championships at G.C Foster College yesterday. - Ian Allen/Staff Photographer