Comparing airfares may provide a rough estimate of the passenger’s carbon emissions, but it is not a fairer indicator of emissions than seat size. Airfare prices are influenced by a variety of factors, including fuel costs, taxes, fees, and demand. The price of a ticket may not necessarily reflect the carbon emissions associated with a particular flight. For example, a shorter flight with a lower airfare may still have higher emissions per passenger than a long flight with a higher airfare because of factors such as the type of aircraft used and the route taken.
According to a study led by UCL, allocating passenger aircraft emissions using airfares rather than travel class would provide a more accurate picture of individual contributions. Emissions calculators estimate emissions based on travel class, assuming that someone traveling in a higher class and thus taking up more space on the plane produces more emissions.
The study, published in Environmental Research Letters, explains how including airfares in calculations reveals which passengers contribute the most revenue to the airline operating the plane, allowing it to fly.
Although in general, premium (business) seats are more expensive than the economy, the researchers found when looking at data that many late bookings in economy class, often made for business trips or by high-income travelers, cost as much as, or more than, premium seats.
An equitable approach to reducing airline emissions should not just deter travelers 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.
Dr. Van Ewijk
Lead author Dr. Stijn van Ewijk (UCL Civil, Environmental & Geomatic Engineering) said: “The paper shows we should follow the money when calculating emissions of individual travelers, as it is revenue that decides whether an airline can operate a plane or not. Someone who has paid twice as much as a fellow traveler 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.”
According to the researchers, using airfares to calculate passenger emissions would benefit climate change efforts by encouraging people of all income levels to use alternative modes of transportation whenever possible. It would also increase corporate emissions estimates because it would allocate more to expensive late bookings, which are frequently made for business purposes.
Implementing a tax proportionate to the cost of the ticket could make the total cost of flying more equitable. Those who purchase the most expensive tickets would face the highest tax, encouraging them to look for alternatives.
Whilst taxes differ between countries, typically the rates are the same across each travel class. Travelers buying expensive tickets, who are more likely to have higher incomes, pay a relatively low tax and are not currently discouraged from flying.
Dr. Van Ewijk added: “An equitable approach to reducing airline emissions should not just deter travelers 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 also consider the distance flown as well as the model and age of the plane, which can indicate how polluting it is.
The authors tested their fare-based allocation approach using a dataset from the United States. They used the Airline Origin Survey database, which contains information on ticket prices, origin and destination, travel class, and fares per mile. They calculated the distribution of ticket prices across all passengers on a typical flight based on this.
The authors allocated emissions to passengers based on the price distribution and compared the results to estimates from widely used emissions calculators. Because ticket prices vary greatly depending on when they are purchased, emissions per passenger vary significantly more than seat size and travel class.
The researchers estimated how a carbon tax on emissions would affect travelers using an economic supply-demand model, depending on whether the emissions the tax applied to were calculated from seat size and travel class or the airfare. A tax on emissions calculated from airfares had a more equitable effect in all scenarios because it reduced flying more evenly across income groups.
