Scientists reveal best way to measure carbon footprint of airplane travel

The price of an airline ticket is a more effective measure of a passenger’s carbon footprint than class of travel, a new study has found.

Travel emissions calculators typically assume that sitting in first class, for example – which takes up more space on the plane than an economy seat – therefore results in being responsible for more emissions.

However, when fares are included in calculations, it shows which travellers contribute the most to airline revenue and enables them to operate, according to a study led by University College London (UCL) that was published on Wednesday.

Generally, it still tracks that premium seats are more expensive – but not always. Many late bookings in economy cost as much as, or more than, premium seats, researchers discovered.

Revenue decides whether an airline can operate a plane or not and so prices should be taken into account, said Dr Stijn van Ewijk, from UCL’s Department of Civil, Environmental & Geomatic Engineering.

“Someone who has paid twice as much as a fellow traveller contributes twice as much to the revenue of the airline and should be allocated twice the emissions. The seat size of each travel class, which is currently used to allocate emissions, is only a rough approximation of how much passengers pay,” he continued.

Researchers hope that the findings will not only change how passenger emissions are taxed and calculated but also encourage travellers to opt for alternative transport, or rethink if their journey is necessary as part of broader efforts cut planet-heating emissions.

Revamping calculations could also reduce corporate carbon footprints as expensive late bookings are often made for business purposes.

Dr Van Ewijk added: “An equitable approach to reducing airline emissions should not just deter travellers who can only afford the cheapest early bookings but also the big spenders who bankroll the airline.

“By assigning emissions based on ticket prices, and taxing those emissions, we can make sure everyone pays their fair share, and is equally encouraged to look for alternatives.”

A ticket tax should take into account the distance, the model and age of plane, which can indicate how polluting it is, the researchers added.

While aviation results in only about one-sixth of the greenhouse gas emissions of cars and trucks, it is used by far fewer people. However, more people are expected to take to the skies in the coming years, the UN’s International Civil Aviation Organisation has said.

While flying overall is hardly a climate-friendly pursuit, commercial air travel is better for the environment than private jets. A 2021 report from the European transport campaign group, Transport and Environment, found that private jets are five to 14 times more polluting than commercial planes, per passenger.