'The ultimate test of a moral society is the kind of world that it leaves for its children'.
- Dietrich Bonhoeffer, German pastor -
What is a carbon footprint?
Your carbon footprint is the amount of greenhouse gas you are responsible for. The total greenhouse gases that humans add to the air cause warming and other changes to our climate.
You produce a tiny amount of greenhouse gas when you breathe out. However, the things you do and buy produce large quantities. The electricity you use at home was probably made by burning coal. The food you eat needed fertiliser to grow it and energy to harvest it. The clothes you wear, the toys you buy and the house you live in all took energy to make. Of course we can't stop eating, playing or living in houses but there are things we can all do to reduce our carbon footprint.
What's my fair share?
In one year the average Australian's greenhouse gas emissions add up to about 28 tonnes. If we shared out the right to produce greenhouse gas fairly across the world, each person would get around 8 tonnes. We also need to reduce our emissions to avoid dangerous climate change. So a reasonable target might be 4 tonnes for every person in the world. New technology can help us to cut down, but it won't be enough on its own. Some of the cuts must come through changing the way people live, particularly in richer nations.
How can I cut back?
Throw away less
In 2004 Australians threw away food worth $5.3 billion. Buy what you need and plan to eat what you buy. You'll save money and greenhouse gas emissions.
Meat is one of the biggest contributors to our carbon footprints and Australians eat a lot of it. Around one tenth of the average Australian's greenhouse gas emissions come from meat. Cattle and sheep need lots of land to graze on, and sometimes trees are cut down for this. They also burp a lot, producing methane, a very potent greenhouse gas. So perhaps cut out red meat once or twice a week, and eat smaller portions of meat.
Kangaroos digest food differently to cattle and sheep, so they don't produce as much methane. They also don't need land cleared in the same way as cattle. So kangaroo meat causes fewer greenhouse gas emissions than other red meat.
Bottled water or tap water?
Making bottles and shipping water across the world is very energy intensive. The greenhouse gas produced for each bottle of water is equivalent to driving a car for two kilometres. Fill your bottle from the tap instead of buying water in a bottle. It's cheap and if you freeze a half full bottle and then top it up with water, it will stay cold all day.
Every extra stage in manufacturing takes more energy. Processed food needs more energy to produce it, package it and ship it than fresh food. More energy means more greenhouse gases are produced.
Some packaging is necessary, but avoid what you can. A bag of individually wrapped lollies, for example, will have much more packaging than loose lollies. Since it takes energy to make the packaging, reducing it cuts greenhouse gas emissions.
Borrow or rent things you don't use so often, like lawn mowers or camping gear. Or share them with a neighbour.
Do things instead of buying things
Services are nearly always lower in emissions than goods, so going to a concert is better than buying a CD. A trip out to the Museum doesn't produce much greenhouse gas, especially if you come by bus.
Buy to last
Buy durable goods that don't need to be replaced so often, rather than disposable or cheap things that will wear out quickly.
Buying second hand goods means no extra energy is needed to make them. It saves you money too. Try the op-shop or web sites like freecycle.
Do you really need that new pair of shoes? Stop and think before you buy - you'll save money and greenhouse gas. Simply cutting down on the amount you buy is the easiest way to reduce your carbon footprint. Every year Australian households waste more than $1000 buying things they never use or only use once.
Repairing your old car or washing machine is usually better than buying a new one, as each new product takes energy to make. But buying a new car does make sense if it is uses a lot less petrol than your old one.
When you have a choice, choose products which have lower greenhouse gas emissions. Try buying local products as products from other parts of the world required fuel and energy to transport them here.
Turn it down (or up)
Heating and cooling your home are big energy users. You can cut costs by turning down your thermostat by 1°C (for heating) or turning it up (for air conditioning).
Insulate yourself and your home
Put on a jumper in winter, and put some insulation into your roof. A window loses ten times as much heat as a wall in winter, and in summer a window can add as much heat to a room as a small radiator, so use curtains to keep heat in or out.
Switch off that second fridge
Your fridge uses more electricity than any other appliance in your house. Older fridges are often much less efficient then newer ones, so if you have an old fridge in the garage recycle it or only switch it on when it's really needed.
Change your method of water heating
Changing your electric water heater for gas or solar could cut your electricity bill in half. Taking shorter showers helps too as it means less water has to be heated.
Living with other people is a great way to reduce your footprint, because you share appliances, hot water and heating and cooling in your house.
Smoother driving rather than speeding and braking can save one third of your car's greenhouse gas emissions. Keep your tyres pumped up to the right pressure, and take out all that stuff you are carrying around unnecessarily in the boot. Driving more slowly helps too.
Almost all of the greenhouse gas produced by transport comes from the petrol you use in your car.
Only fly when it's essential
It is predicted that emissions from flying will increase four-fold by 2050, as more people will travel by plane. If you fly a lot it will have a dramatic impact on your footprint. Leave your footprints on a local beach instead.
Some construction and renovation work is optional. Do you really need that new kitchen or third bathroom?
Use recycled products
Use recycled products, like flooring made from old car tyres or recycled wine corks. Or try materials like bamboo, which grow quickly and absorb greenhouse gases as they grow.
A house of mud
Making bricks from mud and earth takes less than one per cent of the energy it takes to make an ordinary brick, so much less greenhouse gas is produced. Modern earth bricks are strong and waterproof.
How to manage your carbon emissions at the Department of Environment and Climate Change.
Couldn't we just plant more trees?
Growing trees absorb carbon dioxide, one of the main greenhouse gases. They lock it up in the wood they make. So instead of cutting back our greenhouse gases, we could just plant lots of trees to mop it all up, or pay a company to do it for us. This is one way of 'offsetting' our carbon footprint.
However you'd have to plant trees over an area the size of Australia to offset the whole world's greenhouse gas emissions for a year.
Trees grow slowly, so it takes many decades after you plant them for the greenhouse gas to be absorbed. They also die eventually. If they are left to rot, the gas is released back into the air. Usually, when you pay a company to plant trees, they promise to look after the forest for 99 years. So perhaps you are simply time shifting your greenhouse gases, instead of hanging around in this century, you are paying for them to go into the next.
Alternate energy sources
Today humans are heavily reliant on fossil fuels such as oil, coal and gas to generate electricity. This causes more damage to the climate than anything else we do. Instead of burning coal, oil and gas there are cleaner ways to produce electricity.
Alternate energy sources image gallery
Did you know that moving your body can produce electricity? It is possible to capture the energy from your movement and convert it into an electric current. Bicycle dynamos have been doing it for years, but more sophisticated technology can be built into almost anything we move or move on.
Some gyms or dance clubs are already collecting our energy and using it to power their lights and music. On a much larger scale, we may soon be able to harness the power from crowds at concerts, train stations or sporting events.
It's huge, it's powerful and it's constant. The sun provides us with enough energy every hour to provide the world's energy needs for a year. Solar power refers specifically to the conversion of sunlight into electricity through photovoltaic cells or solar concentrated thermal technologies. The challenges are how to capture it cheaply and efficiently and then develop ways of storing the electricity. Without storage, we can't have electricity when the sun's not shining - not much use on a cold dark night. One answer is to combine solar with other technologies, making it one of a mix of possible energy solutions.
Humans have harnessed the wind for thousands of years. We have used it to power boats for sailing and windmills to grind grain. Today wind turbines can create enough electricity to power whole towns. Some companies are now making large turbines with blade diameters of nearly 130 metres, which is about the length of a rugby field.
The wind turns the blades on the turbine to power a generator. This produces electricity which can be fed into batteries or directly into the national electricity grid.
You can't just put a wind turbine anywhere. Not all areas have enough wind, and some of the windiest places are in natural beauty spots or are a long way from cities where people need electricity. However, there are plenty of areas in the world where turbines can make a big contribution to electricity needs.
Water power - tidal energy, wave energy and hydroelectric power
Most Australians live near it, fish from it, swim in it or surf on it. Many others around the world enjoy the same luxuries. But water in rivers and oceans has the potential to be used for more than just recreation. The energy of waves, tides and flowing water can also provide electricity and it's generally a more predictable source than solar or wind power.
Electricity can be generated from the movement of water by tides. One method uses large barrages or dams place across tidal rivers. This relies on the vertical movement in the rise and fall of tides to create electricity. Another method places turbines in large underwater farms. The turbines generate electricity from the mass movement of water by tides.Tidal energy is not yet widely used due to challenges of local geography and engineering. However, it has good potential as tides are more predictable than wind and solar power.
Long tube-like structures are placed on the surface of the sea and move with wave motion. The movement drives generators to produce electricity which is fed into underwater cables and brought to land. Although waves contain plenty of energy only about five per cent is accessible. This is due to the fact that the height and frequency of waves is variable, and few places are suitable for building large wave farms.
Hydroelectricity is the most widely used form of renewable energy in the world. In 2008 it supplied almost 20 per cent of the world's electricity. With more investment, its capacity could triple worldwide but there are issues with space and environmental impacts. Hydroelectricity is generated from the energy of falling or flowing water. Water is usually dammed and as it falls from a height the force of the falling water moves turbines which generate electricity.
Hot rocks - Geothermal power
Can you imagine rocks so hot that they can turn water into steam?
Beneath our feet, in the Earth's interior, lie rocks containing vast amounts of heat. This heat is a constant source of energy and can be used to produce geothermal (meaning 'earth heat') electricity. About 25 countries use this type of electricity, but only a few use it for more than 15 per cent of their electric needs. It can be difficult and expensive to extract this energy, especially if the rocks are too far below the surface.
The nuclear option
The nuclear debate is back to the fore, but with a new angle.
Supporters claim that we must use nuclear power to avoid catastrophic climate change. This is because it produces much less greenhouse gas than burning coal, oil and gas. It is an established technology that could provide the bulk of our electricity needs.
Opponents claim it is dangerous to the environment and there's risk from misuse to produce weapons. There are plenty of better and safer alternatives like solar or wind power. If enough investment was made, these technologies could more than match the capacity of nuclear energy.
Where would you prefer your electricity to come from? Do we have a choice about going nuclear?
What is the world doing now?
- There are over 440 nuclear plants operating worldwide, producing 15 per cent of the world's electricity
- Over 30 countries are actively considering using nuclear power programs
- Nuclear fusion is being investigated as an alternative to current nuclear fission energy. It is suggested that it could meet all our energy needs, is less dangerous than the current process and produces lower levels of radioactive waste. However, it is unlikely that there will be commercial reactors until at least the 2040s.
Catherine Cooper and Fran Dorey
Reference: Australian Museum