Less than half of the world’s 28 largest airlines offer a carbon offset scheme.

And the majority declined to provide data on the number of passengers offsetting their flights during a one year period – often saying their figures were too low to report, according to the BBC.

Carbon offsetting enables passengers to balance out their carbon footprint by paying towards environmental projects.

Aviation accounts for 2% of global human-induced greenhouse gas emissions.

Prices vary but a return flight from London to Malaga, Spain, would cost around £4 to offset.

Edward Hanrahan, chairman of offsetting organisation ClimateCare, said: “We know that many airlines are looking at ways to reduce the environmental impact of their flights – so what can they do in the interim to help their passengers reduce their personal travel carbon footprint?

“If flying, it is essential that either the airline or the customer takes responsibility for the emissions from these flights.

“Some airlines such as Virgin Atlantic and Air New Zealand provide their passengers with easy to use carbon offset calculators. For maximum effectiveness, these should be well signed and effectively promoted to passengers.

“It should also be made as simple as possible for passengers to offset, for example within the booking path and when checking-in online.

“Finally, airlines need to ensure they are working with a reputable partner with a strong delivery track record.”

Iata director Michael Gill said: “We strongly recommend all passengers to use high-quality projects to offset their own CO2 emissions as an individual contribution to addressing climate change.”