How to fly around the world without costing the earth

The easiest way to begin offsetting personal carbon emissions is to visit one of the growing number of websites devoted to redressing the environmental balance.

These provide a ready reckoning of the amount of CO2 your lifestyle is responsible for producing. The three key polluting areas are air travel, car use and the amount of energy consumed by your home.

Starting with air travel, the green traveller or environmentally aware business is invited to scroll through a menu, not unlike those offered by the budget airlines responsible for so many of the extra air miles flown in recent years. By entering a starting location and a destination - and indicating whether the trip is one-way or return - the website will calculate the amount of emissions your seat on the plane will generate.

A one-way flight from London to New York would create approximately two tons of CO2. A cost to offset this is then calculated - in the case of the transatlantic journey the price is set at £15. A similar figure can be calculated for car miles. A typical motorist who drives 10,000 miles a year, at an average of 35 miles to the gallon, can expect to produce three tons of harmful emissions. The cost of remedying this is calculated at £22.50. In order to evaluate the impact your home heating system is having, the sites require the user to simply enter the amount of an annual gas or electricity bill or the KWh used. An average fuel bill of £1,000 will have resulted in 7.68 tons of CO2 being pumped into the atmosphere. Offsetting this quantity of greenhouse gases will cost £57.63. Based on an average of one flight a year, the average family CO2 emissions can be offset for under £100 a year. Like any other internet shopping site, the appropriate amount can be purchased online with the use of a credit or debit card, by simply clicking on the "buy" icon. Offsets can even be given as gifts.

Typical of the new companies is Climate Care, based in Oxford, established in 1998. It offers three ways to neutralise your CO2 emissions.

Firstly it will fund renewable energy programmes - these promote energy sources other than fossil fuels. Secondly it will improve efficiency to cut the amount of energy needed by existing buildings and other consumers of power. Finally it will restore forests by planting trees which absorb CO2 from the atmosphere.

Nicola Scolfield, the company's campaigns and projects manager, said that all its carbon offsetting programmes take place in the developing world. "If our projects were in the UK we would be helping the British Government achieve its Kyoto targets," she said. "We want our customers to be making reductions that have not already been committed to." The projects range from distributing fuel-efficient cooking stoves in Honduras to restoring rainforests in Uganda and building cow-dung-fuelled bio-gas digesters in Rajasthan. "Climate change is a global issue. Taking CO2 out of the atmosphere helps everybody," said Ms Scolfield.