What Makes an Airline 'Emissions-Efficient'? See the Top 10 Rankings

Some airlines are becoming more efficient, but overall emissions are still growing as the sector grows. The bigger picture is how fast aviation is expanding, and what that means for the climate.

Wizz Air has been named the most emissions-efficient airline in a new climate ranking from aviation analytics firm Cirium. The Hungarian low-cost carrier emits around 54 grams of CO₂ per seat per kilometer, according to the review, which was verified by PwC and is the first of its kind in the industry.

That efficiency measure is driven by several key factors, starting with Wizz Air’s relatively young fleet. The airline’s planes average around four years old, and many are up to 25% more fuel-efficient than older aircraft.

Seat configuration plays a role too. Low-cost carriers typically cram more seats into each plane, which reduces emissions per passenger.

One often-overlooked detail: how long a plane spends ta