White paper

Low-cost carriers and U.S. aviation emissions growth, 2005 to 2019

This report provides the first bottom-up, detailed fuel consumption inventory for all commercial flights to, from, and between U.S. airports using our Global Aviation Carbon Assessment (GACA) model. The analysis finds that overall fuel burn and, therefore, carbon dioxide (CO2) emissions from U.S. airlines increased by 7% from 2005 to 2019.

Low-cost carriers (LCCs) are the major driver of U.S. emissions growth. Network carriers offset almost 90% of their traffic growth via improvements in fuel efficiency from 2005 to 2019. In contrast, LCC traffic increased nearly three and a half times faster than fuel efficiency improved in terms of revenue passenger miles per gallon (RPM/gal) over the same period, driving large increases in fuel use and CO2. This is despite LCCs having relatively high fuel efficiency due to factors like newer aircraft, higher load factors, and higher seating densities. As a result, LCCs were responsible for 88% of growth in fuel use and CO2 emissions from U.S. airlines between 2005 and 2019.

These findings suggest the need for a renewed focus on U.S. domestic aviation emissions, which accounted for about 15% of the global total and are not covered by international agreements. In order to meet its goal of capping CO2 emissions at 2005 levels starting in 2020, the United States should pay special attention to the role of LCCs as a driver of overall emissions. Further investments should also be made in sustainable aviation technology. Alternative fuels like hydrogen and limited electrification could be used predominately on regional and short-haul flights. Drop-in biofuels or synthetic fuels could be deployed for use on medium- and long-haul flights for which electricity and hydrogen are expected to be less suitable.