Leaving Your Mark

The total amount of carbon dioxide - and hence the amount of carbon - you release is summed up in your "carbon footprint" - the carbon you leave in the environment due to your activities. This isn't just from your car exhaust - it's from the power used to build and heat your home, and the electricity used to wash your clothes, light your dining room and run your computer and TV.

Even the shampoo you buy and the food you eat contributes - just think, has it been transported by air or road to reach your local shop? And how about the energy used to pack the items, and to make the packing that they are wrapped in?

What's Your Size?

It's extremely difficult to calculate your carbon footprint exactly, though a few people have tried. On average, a single person in the UK releases about 11 tons of carbon dioxide each year - that's enough to fill three hot air balloons.

To help you work out your footprint, try one of the many online calculators that can sum up your main contributions. For example, there's the BBC Calculator and another from the National Energy Foundation.

Clean Up Your Act

Once you know how much you create, you can begin to look at ways to reduce it. Leaving the car at home and walking or cycling to work will make a difference. Buying locally, at your high street rather than at out of town supermarkets will help too. And since every thing in the shops is brought there by large fuel guzzling trucks, if you can find food and produce made or grown locally, you can make a difference.

Use less energy at home - turn down thermostats, switch to energy efficient light bulbs and appliances, and insulate your house.

Offset Your Carbon

There's another solution - just carry on consuming and simply plant trees. This is called carbon offsetting. Say your flight to America releases 10 tonnes of carbon. Now you just plant enough trees to absorb it all. Job Done. But is it a good idea?

Planting trees can certainly remove carbon from the atmosphere: plants use photosynthesis to grow and the process eats up carbon dioxide from the air to create carbon compounds in trunks, branches and leaves. The carbon will stay locked up in the tree - perfect! Plant a forest and save the planet. The feel-good factor this creates has helped transform carbon offsetting into one of the fastest growing businesses in the world.

Does It Work?

Unfortunately things aren't that simple. The offsetting industry is unregulated. Even if you pay a charity or company to offset your carbon, can you be sure that they are planting the right number of trees. Worse these trees could be planted tomorrow and pulled up five years later. Different offset companies can't even agree on how many trees you need to offset a flight from, say, London to New York. Nor can they agree on the price of offsetting a ton of carbon.

There's another problem: carbon is only locked up in a tree while it's alive - if it gets cut down or dies, and it rots or burns, the carbon comes out again. As climate change kicks in, many forests will begin to die back. Will the offset company guarantee that its forests will survive?

A Better Way to Save

Perhaps a better option is to fund small scale renewable energy projects - installing solar power in homes in India or Africa, say. This can help reduce emissions directly by replacing fuel like wood or coal. But once again, without proper regulation it is difficult for consumers to have complete confidence in how money is used. If there's any conclusion to be made, it is simply that it is better not to emit the carbon in the first place...