Flying abroad for your holiday used to be an almost guilt-free pasttime. But now, as our understanding of climate change deepens, more people are offsetting their carbon footprint. Laura Brady asks if it is worth it.

The term carbon offsetting is the undisputed buzz phrase of the day. The principle is simple: you pay a given amount for every carbon emission for which you are responsible and the money helps cancel this out by funding a project that reduces carbon emissions.

Over the past couple of years, carbon offsetting has really taken root. In a recent survey, research agency Ciao found that 73% of the British public said they would be willing to pay £5 to offset carbon emissions for a short-haul flight and £15 for long-haul.

Whether driven by guilt, fear of a damaged reputation or a genuine desire to change the world, both corporate organisations and consumers alike have no objection to putting their hands in their pockets when it comes to the issue of climate change.

This is great news for the growing numbers of carbon-offset providers. The role of these companies is to add up the carbon you have spent for a particular event, in terms of either tonnes of CO2 or carbon credits. They then calculate how much it will cost to effectively buy this carbon back. Your money is then put towards a carbon-reducing project in another area of the world - a renewable energy plant in Mexico or a project in the North Pole to combat the melting ice caps, for example.

Choose your project

Some carbon-offset providers, such as Carbon Footprint, allow you to choose which project you would like your contribution to fund, including its forthcoming conversion of hotels in India to total energy-efficiency. Other providers, such as Climate Care, pool all contributions and distribute the funds across its entire portfolio.

But many environmentalists are looking at carbon offsetting with an increasingly critical eye. As the industry is still in its relative infancy, there's no regulation in place, and it's not even known how many carbon-offset providers exist, although it's likely that there are between 20 and 25.

What's more, as companies are not working to set criteria, the value of a carbon credit can vary between providers. For example, Climate Care works on the basis of a £7.50 charge for every tonne of CO2 produced. "This reflects the cost of running the business and the cost of buying back the tonne of carbon offset," explains business development manager, Nicola Schofield. So if you wanted to offset the 2.1 tonnes of CO2 Climate Care calculates is generated by driving 8,000 miles a year in a car with a fuel economy of 40 miles per gallon you would have to pay £15.75.

But, using the same criteria, MyCarbonDebt.com puts the carbon emission at 2.2 tonnes and says it would cost £25.96 to offset - that's £12.25 per tonne. Meanwhile, PURE (the only registered charity in the carbon offsetting field) puts the carbon emissions at 2.6 tonnes and says it would cost £36.40 to offset, which equates to £14 per tonne.