Scoot tops global airline rankings for lowest emissions; SIA second in South-east Asia

SINGAPORE – Scoot has topped global airline rankings for lowest emissions in 2025, while its parent company Singapore Airlines (SIA) has been ranked second in South-east Asia, according to a global study by aviation analytics firm Cirium.

Scoot is also the first South-east Asian carrier to top the global rankings, overtaking Hungarian low-cost airline Wizz Air, the 2024 leader, Cirium said on April 15 when it released the study.

The study looked at the world’s 100 largest scheduled passenger airlines based on the amount of carbon dioxide (CO2) they emit for every seat flown per kilometre, which measures how efficiently airlines use fuel.

SIA ranked behind Vietnamese low-cost airline VietJet Air in the South-east Asia rankings and ahead of other full-service carriers in the region.

Both Singapore carriers performed well because of strong operational and fleet decisions, said Mr Mike Malik, chief industry officer at Cirium, at a virtual press conference on April 14.

On Scoot’s ranking, he pointed to its relatively young fleet and high seating capacity.

“(Scoot) operates one of the youngest fleets... and has the highest (average) seat count at 242. The combination of new aircraft and the best (seat) configurations is exactly what the data tells us drives efficiency,” he said.

The rankings measure how much CO2 is produced for each seat flown over a distance. An airline can score better either by using less fuel overall or by carrying more passengers on each flight.

While sustainable aviation fuel is expected to play a major role in the industry’s path to net zero by 2050, production today still meets only a small fraction of total fuel demand, Cirium chief executive Jeremy Bowen said.

“Increasing supply and reducing cost will take years,” he said.

In the meantime, airlines’ day-to-day operational choices – including aircraft type, cabin density and routes – remain the most immediate levers for cutting emissions, he added.

Cirium’s analysis takes into account factors such as the type of aircraft used, its configuration, how far it flies and how much fuel it burns. Professional services firm PwC independently checked the study’s methodology.

Cirium has said flying with more efficient airlines can significantly affect an individual’s carbon footprint, even on the same route.

Aviation emissions are among the hardest to reduce, but passengers can still play a part, said Mr Rueban Manokara, global lead of carbon finance and markets task force at the World Wide Fund for Nature Singapore.

“Every flight carries a real carbon cost, so our choices to support cleaner options directly shape how fast the sector can transition (to net zero),” he said.

Clear emissions data, such as airline rankings, can help travellers make more informed decisions and nudge the industry towards cleaner options, alongside efforts by governments and airlines, he said.

Mr Alexander Kunkel, a senior data analyst for clean fuels at Transport & Environment, said such rankings help travellers understand how to reduce their carbon footprint.

He added that consumers should use the rankings to inform their travel choices – including flying less frequently, opting for flights that use sustainable aviation fuel where possible and choosing rail for shorter distances.

Scoot’s fleet has an average age of 6.7 years and an average of 242 seats per aircraft. It operates a fleet of more than 50 aircraft, according to its website.

Scoot recorded emissions of 51g of CO2 per available seat kilometre (ASK) in 2025, a slight improvement (minus 0.1 per cent) from 2024.

With more seats on each aircraft, airlines such as Scoot can spread fuel use across more passengers, lowering emissions per seat, Mr Malik said. Newer aircraft also tend to burn less fuel, making them more efficient overall.

In second place globally, Wizz Air’s score was 52.9g of CO2 per ASK, while third-placed British-based charter airline TUI Airways recorded 53.6g CO2 per ASK.

Mr Malik said SIA’s result was also notable, given its different business model as a full-service airline.

“It’s an important result because it’s a full-service carrier, and they’re competing on efficiency alongside the low-cost carriers in (South-east Asia),” he said.

Full-service airlines such as SIA typically have more premium seats and fly longer distances, which means fewer passengers per flight and higher emissions per seat. Despite this, newer aircraft and improved operations are narrowing the gap with budget carriers, Mr Malik added.

In the South-east Asia category, SIA recorded emissions of 66.7g CO2 per ASK, behind VietJet’s 64.5g CO2 per ASK and ahead of Indonesian low-cost carrier Lion Air’s 67.1g per ASK.

A spokesperson for the SIA Group said on April 17 that more than three-quarters of its fleet now comprise newer-generation aircraft that are about 25 per cent more fuel-efficient than the models they replaced.

The group, which includes SIA, Scoot and cargo operations, expects newer-generation aircraft to make up 90 per cent of its fleet by 2030.

SIA also ranked eighth in the transpacific region, at 70.3g CO2 per ASK. The top three were Air Canada (56.2g), Delta Air Lines (57.5g) and Cathay Pacific (59.8g).

These inter-region rankings focus on average CO2 per ASK for flights that span different global regions. This reflects emissions across long-haul and wide-body operations.

In response to a question on how emissions are likely to change in 2026 across airlines, given issues with jet fuel, fuel supplies and fuel prices due to the war in Iran, Mr Malik said external factors such as airspace and airport closures could affect emissions in 2026, as airlines may need to take longer routes.

“I don’t know if (the war) is going to make a difference to emissions, because the demand is still out there. The problem is the airspace closures and airport closures that require airlines to make longer routings. That’s going to increase emissions for them because they burn more fuel that way,” he said.

The Cirium study also ranked the world’s largest airlines – based on capacity and scale – by CO2 per ASK, with Qatar Airways, Ryanair and Turkish Airlines also producing the lowest emissions per passenger. Across regions, low-cost airlines and those with newer fleets performed better.