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Slowing Down Global Warming

Pupils' Information Sheet

Introduction

In previous lessons it has been seen how humans are responsible for releasing large amounts of the greenhouse gases into the atmosphere and how this will, in future, start changing climates around the world. Is there anything that can be done to stop or slow down global warming? The answer is yes, but it is easier said than done.

Global warming is a global problem. Once greenhouse gases are released, they will mix with the rest of the atmosphere. So even if the UK stopped emitting any greenhouse gases tomorrow, our climate and climates throughout the world would still change. This is why countries all over the world have to co-operate if the problem of global warming is to be addressed.

Some people say that because we are not sure about how much climates will change, or how quickly, we should wait to see what happens. They can't see the climate changing, so it is not really happening. The truth is if we wait to see what happens, it may then be too late to prevent a lot of the damage. Already the temperature of the world is increasing. That is why scientists and governments around the world are talking about what all of us can do to help prevent global warming.

What has energy got to do with global warming?

Almost half of the enhanced greenhouse effect is due to our use of energy. That is because our main source of energy is from the burning of fossil fuels like oil, coal and natural gas. The burning of any fossil fuel, or wood, produces energy and carbon dioxide, so increasing global warming. People can't live without using energy, so what can be done?

'Cleaner' energy

Some sources of energy don't release any carbon dioxide into the atmosphere. These include wind power, wave power, hydro-electricity (electricity made from flowing water) and solar power (otherwise collectively known as renewable energy). If we used these instead of fossil fuels, less carbon dioxide would be produced. The trouble is that it would be very difficult and very expensive to get all our energy from these sources.

Another kind of energy source that doesn't produce carbon dioxide is nuclear power. Some countries use a lot of nuclear power (e.g. France), but many people are worried that it is very dangerous in other ways such as the possibility of radiation leaks. For this reason it is unlikely that the amount of nuclear power in the world will increase rapidly.

It is possible that new or improved ways of producing cleaner energy will be developed in the future, but until this happens we should try to use the energy available now more efficiently.

Energy efficiency

A lot of the energy we produce is just wasted. When electricity is made by burning coal in power stations, more than 60% of the energy from the coal is lost as waste heat. Power stations can be made more efficient by finding uses for the waste heat, or by using more efficient fuels such as natural gas.

If you live in a draughty house, your gas fire or central heating system will have to burn more fuel to keep the house warm. Energy can be saved by fitting draught excluders, insulating hot water tanks, or turning down the thermostat by just one or two degrees.

Cars burn petrol or diesel, which are types of fossil fuel, so we should try and use them less, and buy cars which use fuel more efficiently. A bus or train emits less greenhouse gases than several cars carrying the same number of people, so many people think that we should have more buses and trains and fewer cars. Bicycles emit no greenhouse gases at all!

It will even help if you use less electricity by turning off lights when they are not needed, or only boiling as much water as you need in the kettle. If everyone were to use less electricity, the power stations would have to burn less coal, oil and gas to keep everyone supplied with the energy they require. One problem is that making power stations, factories, buildings or cars more energy efficient costs a lot of money in the first place.

How important are CFCs to the greenhouse effect?

Lesson three looked at how ozone is being destroyed by CFCs, but, as mentioned in Lesson one, CFCs are also very important greenhouse gases. They are thousands of times more effective than carbon dioxide at stopping the heat escaping from our atmosphere. Nearly a quarter of the enhanced greenhouse effect in the 1980s was from use of the family of compounds, called halocarbons, to which CFCs belong. They are used in fridges and freezers, aerosol cans and fire extinguishers.

Many countries have agreed to stop using CFCs, and eventually to stop using their less harmful replacements, HCFCs.

Can forests help slow down global warming?

Trees absorb carbon dioxide, removing it from the atmosphere. The carbon is stored in the tree as it grows, so young forests can remove a large quantity of carbon dioxide and store it for many years. When trees are cut down, two things can happen: first, the forest can't absorb as much carbon dioxide from the atmosphere; secondly, a lot of the wood (such as roots, twigs and small branches) is often burnt, releasing the stored carbon as carbon dioxide.

The world's forests are being chopped down at an alarming rate. As much as 154,000 km2 of tropical forest are chopped down every year, an area about the same size as England. The wood is used for timber or paper, and the land for agriculture. Very few trees are replaced. A long time ago nearly all of the UK was covered with forests; now they cover only about 10% of the land.

One easy way to help stop forests being chopped down is to use and waste less paper, and to recycle the paper we do use. Young forests, where most of the trees are growing quickly, are very good at removing carbon dioxide from the atmosphere, so it is a good idea to plant or extend forests. Already in some forests a new tree is planted every time an old one is cut down. This is called sustainable forest management.

Agriculture and the greenhouse effect

Cattle and other livestock, and rice growing are responsible for the production of a large amount of methane (CH4), which is an effective greenhouse gas. A reduction in the amount of intensive or 'factory' farming would lessen the increase in methane.

In addition, farmers use a great quantity of artificial fertilisers which produce a gas called nitrous oxide (N2O), another greenhouse gas. Some crops are grown organically, without artificial fertilisers, but a similar area of land would not be able to grow as much of the crop as land that had been treated with fertiliser. This is why organically grown produce costs a lot more than ordinary produce.

Developing countries and their contribution to the greenhouse effect

The populations of the developing countries are growing very quickly. All these people must use some source of energy (usually wood) for heating and cooking, and they also need to clear forested land to grow crops. All these activities will produce greenhouse gases. If they are very poor, they won't have enough money to spend on the more expensive sources of energy which don't produce greenhouse gases. For most people around the world, fuels like wood are the main source of energy. Often this is used very inefficiently in open fires, because people can't afford simple stoves. Industries in developing countries cannot afford expensive technology to reduce their greenhouse gas emissions.

Aid from the developed world would help the developing world to buy the technology it needs to reduce greenhouse gas emissions, or to adapt to the effects of climate change. As part of an international effort to slow down the emission of greenhouse gases, the developed world will pass on some of its technological discoveries to allow the developing world to develop cleaner and safer sources of energy such as solar power.


Questions / further work

1. Can you think of ways in which energy could be used more efficiently in your house?

2. One way of producing energy more efficiently is through a Combined Heat & Power (CHP) plant. Can you find out how these systems work and investigate if they are being used in your area?

3. Find out what type of energy is used in your own home and how much it costs to run through a twelve month period (ask your parents for the old bills).

4. If 154,000 km2 (the size of England) of tropical rainforest is chopped down in a year, how long would it take to chop down a forest the size of the United States of America?