As of 2018, the commercial aviation industry accounted for 2.5 percent of all greenhouse gas emissions. If it were its own country, it would be the 7th highest emitter on the planet.

Because of this, some climate activists have begun calling on people to reduce the amount of time they spend in the air, or to stop flying all together. Two Swedish moms, for example, got at least 10,000 people to pledge not to fly at all in 2019 as part of their No-fly 2019 (Flygfritt 2019) campaign, as BBC News reported.

But if you do need to fly, it turns out not all airlines are carbon-equal. A report released Tuesday from the London School of Economics' (LSE) Transition Pathway Initiative (TPI) compared what the 20 top publicly-traded airline companies are doing to combat climate change, and found that only one — the budget airline EasyJet — was on track to keep its carbon dioxide emissions low enough after 2020 to meet the Paris agreement goal of limiting warming to below two degrees Celsius above pre-industrial levels.

In general, the study found that the entire industry had to do better. No company had a clear plan to reduce emissions past 2025. Further, many companies that had adopted emissions reduction targets relied on carbon offsetting. But the International Energy Agency (IEA) has found that limiting warming to below two degrees is only possible if airlines actually reduce their own emissions.



However, some airlines are doing more than others. The study rated airlines on both the quality of their overall climate change management plans and their emissions per passenger kilometer (the number of passengers multiplied by the distance flown).

In terms of Management Quality, Delta, United, Lufthansa and Japan-based ANA Group scored the highest, while Air China; China Southern; Korean Air; Singapore Airlines and Turkish Airlines scored lowest. One airline, Wizz Air, scored even lower, but it has disclosed more data to LSE since the study was undertaken.

In terms of projected emissions (in grams of carbon dioxide per passenger kilometer) by 2020, the airlines rank as follows, from most to least efficient.

EasyJet: 75 Alaska Air: 87 Qantas: 89 United: 92 Southwest and Jetblue: 98 LATAM: 102 Delta: 104 Lufthansa and Turkish Airlines: 107 Air China: 108 IAG: 112 Japan Airlines: 125 ANA Group: 133 Korean Air: 172

There was no 2020 data for American Airlines, China Southern or Singapore Airlines, and no data at all for Wizz Air and IndiGo.

BBC News issued a caveat about EasyJet's high performance, however:

There is also some cause for caution over EasyJet's carbon virtue. Remember that the figures are based on CO2 per passenger kilometre.



This means EasyJet can improve its per capita performance by stuffing planes with cut-price ticket-holders, thereby potentially encouraging a new generation of frequent flyers.

Indeed, the International Air Transport Association (IATA) expects the number of airline passengers to double to 8.2 billion by 2037, which could make the sector's emissions worse, CNN reported.

The study itself is proof of growing pressure on the airline industry to reduce emissions, however. It was funded by the Environment Agency Pension Fund, which represents institutional investors who want their money to go to companies that are making an effort to reduce their carbon footprint.

"Investors have a clear message to the aviation sector," co-chair of the Transition Pathway Initiative on behalf of the Environment Agency Pension Fund Faith Ward said in the study press release. "When it comes to carbon performance they must be in it for the long haul. That means setting stretching emissions reduction targets to 2030 and beyond, and ending a reliance on offsetting. It's clear from TPI's research that this is not currently the case."