Only 7% of flyers are funding green energy projects to offset the carbon emitted on their flights, according to a survey.

A study of passengers at Stansted airport revealed that 93% of those questioned did not offset their flights. Ignorance cannot be blamed: 56% of those questioned by the Civil Aviation Authority knew what the practice meant.

Asked if they had taken fewer flights over the previous year on environmental grounds, only 9% of those asked said yes. Most of this 9% took one or two fewer flights. When asked if their choice of airline had been affected by how environmentally friendly they were, only 3% replied in the affirmative.

In total 318 travellers were surveyed in September last year, the most recently available figures. British Airways and easyJet, which both allow passengers to offset their flights directly on their websites, said that the number who chose to do so this year was "static" compared to last year, without giving more details.

Carbon offsetting was first practised by individuals on a meaningful scale about five years ago in response to mounting concern over global warming. It fostered a new industry which set up green energy projects, mostly in the developing world, which consumers could fund to offset their emissions.

Initially, regulation of the new industry was lax and some projects were not properly audited to make sure that the claimed carbon emission savings were actually taking place.

Even though the carbon offsetting industry is now more professional, some environmentalists believe the principle is misguided.

Friends of the Earth said: "Carbon offsetting is a con – it encourages businesses and individuals to carry on polluting when we urgently need to reduce our carbon emissions. It allows people to develop the mindset that it's OK to carry on polluting if green schemes in far-off locations make up for it.

"The greenest thing holidaymakers can do is choose a location that is closer to home, that can be reached by coach or by train. The travel industry must do more to promote nearby towns, coasts and countryside, and the government must ensure rail is a fast, convenient and affordable alternative to flying."