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Everyone knows that carbon dioxide (CO2) is a greenhouse gas (GHG), it traps heat from the sun and promotes global warming. What people often don’t realise is that there are many other greenhouse gases.

Water vapour (H20)

Water H20

Water vapour is the most important GHG but humans have very little influence over the amount in the atmosphere. As temperatures rise so more water evaporates to become water vapour, which traps more heat, which causes more evaporation which traps more heat...and so on.

Methane (CH4)

Methane CH4

Methane is produced by biological activity, but can be increased by human activities. It is 20 times more effective at trapping heat than carbon dioxide. Methane is emitted from the decay of organic matter in waterlogged soils like peat bogs and from the digestive tracts of grazing animals (for example cows!).

Daisy the cow's toxic farts

Daisy and Friends

In fact, Daisy the cow’s methane farts are responsible for four times as much global warming than the farmers! Other additions from human activities include the increased number of livestock, the increased use of landfills for rubbish disposal and leakage from gas pipelines.

Nitrous oxides (NOX)

Nitrous Oxides

Nitros Oxides are produced largely by petrol and diesel engines. They are not as powerful as carbon dioxide but they stay in the atmosphere a lot longer. This means that weight for weight nitrous oxides are 296 times more damaging than carbon dioxide.


What has sheep urine got to do with it?

A British company has come up with a possible solution to this problem: sheep urine! The urine is collected by the fertiliser industry from farmyard waste and refined into pure urea. This is then sold on for use in green engine technology. Ammonia from the urea reacts with nitrous oxides in the exhaust fumes and converts them to nitrogen gas and water. This is then released as harmless steam. So perhaps the car of the future will have a sheep in its tank.

Sheep Power!

Chlorofluorocarbons (CFCs)

Methane CH4

Choloroflourines (CFCs) are produced entirely by human industry. CFCs have been used in air conditioners, refrigerators and freezers. CFC use has been vastly reduced but these chemicals stay in the atmosphere for a very long time.

Ozone (O3)

Ozone O3

Ozone (O3) is a greenhouse gas. It is important not to confuse the presence of ozone high in the stratosphere, where it filters out dangerous ultra violet rays, with the presence of ozone in the lower atmosphere, where it can damage crops and give people respiratory problems as well as increasing the greenhouse effect.


The amounts of these GHGs (CFCs and ozone) are increasing (although CFCs are being largely eliminated and their concentrations have begun to drop in the lower atmosphere). Most of these emissions come from developed countries where power generation, power consumption and living standards are highest.

The big questions:

Are CO2 emissions as significant as the media would suggest?

Are we doing enough to combat the other greenhouse gases?

Wind Turbines

The UK’s position in the world makes it one of the best locations for using renewable energy. In this country we can certainly do wind, in fact we are windier than about 90 per cent of the Earth's surface.

Wind power will only ever be able to supply about 10 per cent of Britain’s energy needs, but when the wind stops blowing other sources of energy must be able to take over. This is still a lot of power, about 12,000 MW (12,000,000,000W).

Wind Farm

How many?

A huge turbine about 80 metres in height with a 65 metre blade produces about two megawatts (MW). So we would need about 6000 of them to supply just 10 per cent of the UK’s energy needs.


Not in my back yard! Where should we put them if we decide we want them? Although they don’t cause any chemical pollution (after manufacturing) they are not exactly easy to hide. It is possible to put about 20 turbines on one square Km but that would still mean 300 square km of land being turned into wind farms.

They are definitely noisy and a lot of people see them as visual pollution of the landscape. Off shore wind farms can be built but costs are high.

The big questions:

Are wind turbines a good thing or a bad thing?

To help you decide, think about:

Global warming, are you worried about this?

Would you want a wind farm on your favourite part of the countryside?

Do you think reducing people’s energy use by 10 per cent would be a better way to spend public money?

Could you use 10 per cent less energy per day? How could you do this?