A new study by the International Council on Clean Transportation (ICCT) on aviation fuel burn and associated greenhouse gas emissions has found that overall fuel burn and, therefore, CO₂ emissions from US airlines increased by 7% from 2005 to 2019. Further, the study found that low-cost carriers (LCCs) such as Spirit, Frontier, and Southwest have driven virtually all that airline emissions growth since 2005.

Source: “Low-cost carriers and US aviation emissions growth, 2005 to 2019”

The paper provides a bottom-up, detailed fuel consumption inventory for all commercial flights to, from, and between US airports using The ICCT’s Global Aviation Carbon Assessment (GACA) model.

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 US airlines between 2005 and 2019.

—“Low-cost carriers and US aviation emissions growth, 2005 to 2019”

Other key findings are:

• LCCs, while operating more fuel-efficient fleets, are growing much faster than fuel efficiency can offset emissions. Over the period studied, LCC traffic grew ~3.5x faster than fuel efficiency improved, increasing fuel use and CO₂ by 64%.

• Pre-COVID, airlines were on track to break the US goal of capping aviation emissions at 2005 levels starting in 2020. The COVID-19 traffic downturn gives airlines five more years to achieve the US goal en route to net-zero emissions.

  
  

• The fuel efficiency, and therefore carbon intensity, of flights can vary by a factor of three over the same stage length. This finding highlights the value of disclosing GHG emissions to consumers at the point of ticket purchase so that they can choose less emitting flights and carriers, the authors said.

  
  

The study comes as a wave of LCCs file for initial public offerings, and as the Biden Administration considers how to incorporate aviation emissions into an economywide net-zero target for the US. LCCs, while fuel-efficient, are growing much faster than network carriers and have been slow to adopt net-zero targets for their operations, the authors said.