Planning a trip to some exotic destination, or just travelling across the country to visit family? If you're going to fly at night, over a long distance, then you may be contributing as much carbon into the atmosphere as you would over an entire year of driving the family car.

When the Intergovernmental Panel on Climate Change (IPCC) released its recent report, many budget airlines were defensive against accusations that air travel contributes a disproportionate amount of Greenhouse Gases into the atmosphere.

As with many impacts upon our environment, it really comes down to the choices we make as individuals. And when we fly to overseas destinations, for most of us it's a holiday -- a choice we make because we are among the minority who are fortunate enough to afford air travel.

Although debates are raging about the looming peak in world oil supplies and its consequences upon all forms of transport, climate change, according to the majority of scientists, is very real.

A lot has been said about carbon offsets. Basically, if you cause an impact doing one thing, do or create another action that balances out the amount of carbon emitted and absorbed.

One positive thing you can do is at least know what impacts you are having on the world's climate. Better to be informed than ignorant.

However, the carbon offset principle has been criticised by some experts as being similar to "pushing food around your plate and not eating it". In other words - it can be used as an excuse not to change our actions.

Read more on this point here.

If you're planning to fly, then before you go take a look over the sites contained in the link below which help with calculating your carbon emissions.

Carbon offset programmes offer voluntary donations to projects which either aim for greater efficiency, fund renewable energy, or support tree planting projects. They are therefore specific to your country.

The sites also offer tips on what you can do to offset the carbon. Choose sites from your country to make calculations easier -- as you can see from the example calculation below.

Note: results will vary between calculators, as calculating your true emissions is a complex process.However, as with any automated calculation, you are relying on the accuracy of someone else's work.

For projects offering revegetation projects, read here first.

Click here to view various carbon neutral sites and their calculators.

Other recommended sites

Sustainable Travel International

Responsible Travel

David Suzuki Foundation

An example carbon emission calculation - Air Travel

Los Angeles to Sydney, Australia

Total Distance = 12061 Kilometres (7494 miles)

Total CO2 = 3.6 tonnes (about 3.5 ton) per person (one-way)

Equivalent car use to achieve to same level of CO2 emissions - medium size petrol car (2 litre) driven for a year at 330 kilometres/week

(for those of you in the US - A vehicle achieving 25 miles/gal, driven 10,000 miles)