Airlines have yet again come under fire for offering frequent flyer incentives to customers, which have been decried as "irresponsible" for encouraging carbon-intensive travel behaviors.

Fresh research released by climate charity Possible estimates that the average air passenger would have to travel on enough flights to emit greenhouse gas emissions of between 5.6 and 92.8 metric tons each year in order qualify for frequent flyer membership programs offered by airlines.

That is as much as 112 times higher than the carbon footprint of a typical person who travels by flight, which underscores the "colossal" climate impact of those who fly enough to gain membership of frequent flyer incentive programs, the charity said.

The report found that lifetime membership status of a frequent flyer program — such as those offered by British Airways and Virgin Atlantic — can require emitting more than 1,800 metric tons of greenhouse gases per person, which it said was 34 times more carbon dioxide than the lifetime per capita share of the remaining carbon budget to limit climate change to 1.5 degrees Celsius.

Possible said the findings demonstrated the need for an "immediate end" to frequent flyer programs offered by airlines operating in the U.K., backed by the introduction of a frequent flyer levy and a kerosene tax which the charity said could reduce "excessive, wasteful consumption of high-carbon travel."

Alethea Warrington, senior campaigner at Possible, said frequent flyer incentives were "sending emissions soaring in the wrong direction."

"Airlines are incentivizing a small group of incredibly frequent flyers to take flights they don't even want, just to get points — while people around the world pay the real price as they face dangerous heatwaves and out of control wildfires," she said. "Airlines need to end this irresponsible behavior, and stop awarding points for pollution."

At present, frequent flyer programs (FFPs) form a "key part" of many airlines' business models, as they can help to drive ticket sales by incentivizing customers to pay for the most carbon-intensive seating options in business or first class as well as encouraging passengers to fly more than they might otherwise need to, according to Possible.

The charity also stressed that frequent flyer programs were only used by a "small but prolific" demographic of regular flight travelers, who it said were responsible for a "disproportionately large" share of flights and emissions.

In some cases, frequent flyer program members have been known to deliberately undertake long and convoluted journeys featuring multiple flights just so they can collect more points which can then be used as discounts for future flight tickets, Possible said.

However, both Virgin Atlantic and British Airways defended their use of frequent flyer initiatives in response to Possible's report.

In a statement, Virgin Atlantic said it does not expect its customers to travel just to earn more points through its frequent flyer program, and therefore offers members different earning and spending opportunities both in the air and on the ground.

"Flying Club is our loyalty program designed to reward those who choose Virgin Atlantic when they travel, rather than based on their flying frequency," it said in a statement. "Our customers can earn Virgin Points through a variety of purchases, from everyday items to higher value experiences, with the majority of points earned on the ground through our credit cards. When customers do choose to use their points to fly with us, they are doing so on one of the most fuel-efficient fleets across the Atlantic."

British Airways, meanwhile, said it would continue to "recognize our customers' loyalty" by offering benefits through its Executive Club program, but acknowledged "the need to balance this with our environmental commitments."

"As part of our BA Better World program and commitment to net zero emissions by 2050, we have a clear roadmap and have introduced a range of measures, including investing in the development of sustainable aviation fuels, flying more fuel-efficient aircraft and investing in the growth of zero emissions hydrogen-powered aircraft," the airline said in a statement. "In addition, our 'CO2llaborate' platform gives customers the option to calculate and address their emissions before, during or after their flight. This includes the purchase of sustainable aviation fuel and carbon removals credits."