For travelers committed to protecting the environment, your choice of airlines, planes and seats can make a big difference. A new report by the International Council on Clean Transportation (ICCT) has ranked 20 major airlines flying between the US and Europe by their carbon footprint.

Norwegian Air Shuttle ranked first as the most environmentally friendly airline because of a combination of its seat numbers and use of newer aircraft which have lower fuel burn. Also ranking high with above-average fuel efficiency were WOW Air, SWISS, KLM, Turkish Airlines, Air France, Thomas Cook, and Virgin Atlantic.

British Airways ranked as the least fuel efficient airline. Its fuel-efficiency actually worsened by 4%, compared to a previous ranking in 2014 by the ICCT. Lufthansa ranked second from the bottom of the list.

Among US airlines, Delta Air Lines performed best with an industry-average fuel efficiency, while both American and United ranked below average. United actually came in third from last only 1% more fuel efficient than Lufthansa.