Why major airlines are so much less environmentally friendly than budget carriers

When the International Council on Clean Transportation (ICCT) released its recent report on the world's most fuel-efficient airlines of 2014, it revealed that major European carriers are not as fuel-efficient as their smaller, low-cost counterparts.

Norwegian, Air Berlin, and Aer Lingus are at the top of the efficiency list. These airlines are known for low-cost, hybrid operations that feature an emphasis on fewer premium cabin seats than their bigger rivals. That distinction is important because the study uses seating configuration and fuel burn as key metrics in determining the fuel efficiency per available seat kilometer (a measure of a flight's passenger-carrying capacity).

The available seat kilometer is calculated by the number of seats available multiplied by the distance flown. Partly because smaller, budget carriers generally have a smaller business class and more seats, they are generally more fuel efficient. The least fuel-efficient of the European carriers is British Airways, followed by SAS and Lufthansa, and according to the study, premium seating is responsible for nearly half of the emissions from airlines like British Airways and Swiss.

Similarly, Alaska, Spirit, Frontier and Southwest all came out way ahead of the major U.S. carriers in a similar study.

Researchers also attributed part of the problem to these carriers flying older planes that guzzle more fuel, such as the Boeing 747-400s flown by British Airways and Lufthansa. These three airlines alone were responsible for one fifth of the available seat kilometer traffic.

ICCT looked at the top 20 airlines plying routes across the Atlantic in its study. It showed that the average, roundtrip transatlantic flight was responsible for one ton of CO2 emissions per passenger, which is equal to the emissions of a 35-kilometer daily commute of a Toyota Prius over the course of an entire year. That's a lot of driving for just one roundtrip jaunt overseas.

The study points out that Norwegian's Dreamliner aircraft used on transatlantic flights are far more fuel-efficient, which is a major reason why it appears at the top of the list.

Just some food for thought the next time you are sipping champagne over the Atlantic.