Aviation data experts Cirium have published their EmeraldSky Annual Review, ranking the world’s airlines on their carbon efficiency in 2025.
The list is decided based on CO₂ per available seat kilometres (ASK). Ousting Wizz Air from the number one spot are Scoot, the low-cost subsidiary of Singapore Airlines. With an average seat density of 242 per aircraft, the carrier produced 2.0 megatonnes (mT) of carbon in 65,000 flights. Its position on the list was supported by longer average flight distances of 2,157km.
Wizz Air fell to second place with 6.2 megatonnes (mT) in emissions across 355,000 flights. Its young fleet, averaging 4.7 years in service, supports its high placement on the list. Other airlines with newer, more fuel efficient aircraft also ranked well, including American LCC Frontier Airlines (5th place, fleet age of 4.8 years) and Pegasus Airlines (9th place, 5 years).
Ranked by ASK alone, Qatar Airways came out on top, followed by Ryanair and Turkish Airlines.
Jeremy Bowen, CEO of Cirium, commented:
Airline emissions performance comes down to decisions airlines can control — fleet choices, seat configuration and how aircraft are deployed on routes. The airlines at the top of these rankings have got those fundamentals right, and it shows. Better emissions efficiency and lower fuel bills go hand in hand.
The top 15 airlines for carbon efficiency according to Cirium are:
- Scoot
- Wizz Air
- TUI Airways
- Air Europa
- Frontier Airlines
- TUIfly
- Virgin Atlantic
- AirAsia X
- Pegasus
- Jetstar
- Condor
- Spirit Airlines
- Iberia
- Volaris
- IndiGo
The list favours low-cost, short-haul airlines. At the same time, Virgin Atlantic’s high position in the top 15 shows that long-haul carriers operating newer aircraft at high capacity can still become far more carbon-effective.
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