Alaska Air
Frank KovalchekAlaska Air is the most climate-friendly domestic airline.

Air travel is the most carbon-intensive mode of transportation, and the industry has long resisted efforts to improve its efficiency — which is weird, given the high price of aviation fuel (it’s basically the Moët & Chandon of refined oil).

But some airlines are more efficient than others. The nonprofit International Council on Clean Transportation analyzed domestic airlines’ fuel consumption, passenger and flight data from 2010 to produce a fuel-efficiency metric.

The analysis revealed that you can personally reduce your airborne carbon footprint by traveling with smaller carriers. The most egregious global warmers tend to be merger-prone corporate giants. From the findings, published in a new report [PDF]:

Of the carriers with above average fuel efficiency in domestic operations, Alaska Airlines (ranked first), Spirit Airlines (tied for second), and Hawaiian Airlines (tied for second) are relatively small carriers serving geographically limited markets.

Many, although not all, of the carriers with worse fuel efficiency than the industry average were, or subsequently have been, the subject of merger activity, including Delta Air Lines (11th), US Airways (12th), Airtran Airways (13th), and American Airlines (14th). The least efficient airline in this ranking, Allegiant Air, also happened to have the most profitable U.S. domestic operations during the 2009 to 2011 period.

Here are the full results:

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