Jet fuel climbs sharply as percentage of U.S. greenhouse gas emissions

In the United States, from 2013 to 2017, jet fuel use has jumped as a percentage of total greenhouse gas emissions, according to the most recent national inventory report (.pdf) released this April by the U.S. Environmental Protection Agency (EPA).

In 2013, jet fuel was responsible for 213 million metric tons of carbon dioxide equivalent emissions (CO2e), which represented 3.1% of the U.S. total (6,776 million metric tons). By 2017, jet fuel emissions climbed sharply to 250 million metric tons, which represented 3.8% of a slightly smaller total (6,534 million metric tons) [updated Aug 17 with small correction].

This means that, in just four short years, in the midst of a climate crisis, aviation emissions as a percentage of the U.S. total rose by more than 20% (one fifth) to reach unprecedented high levels in 2017.

“Using these radiative forcing factors, aviation was responsible for between 7.6% and 11.5% of U.S. carbon dioxide equivalent emissions in 2017.”

The impact of aviation is yet higher if one counts the “radiative forcing” due to the impact of high-altitude aviation emissions. This consideration may double (using an estimate from the CoolClimate calculator) or triple (using an estimate from Lee et al., 2009, in the journal Atmospheric Environment) the climate impact of aviation. Using these radiative forcing factors, aviation was responsible for between 7.6% and 11.5% of U.S. carbon dioxide equivalent emissions in 2017.

Moreover, all of these statistics count only the CO2e emissions from burning jet fuel. All other climate impacts of aviation, including materials and construction of the airplanes, and construction and operations of airports, are in addition to the numbers above.

It is sometimes stated that aviation is responsible for 2% of greenhouse gas emissions, without noting that contemporary U.S. aviation emissions are far higher. The most frequently given citations are to trade association web pages that lack details, or to a 20 year old IPCC estimate of global emissions that has not been updated. In the U.S. context, scientists and climate action advocates should no longer use this 2% figure unless they explain it more precisely.

[New paragraph Aug 21] An electric aviation technology company, AeroTEC, reports estimates that flying is 12% of emissions in the United States, and 4.9% globally, but it does not link to an authoritative information source. Overall, we simply need a scientifically authoritative current estimate of the direct and life-cycle climate impact of the aviation industry to replace the widely cited 2% number.

The high level of U.S. aviation emissions has been overlooked for several reasons, including the fact that jet fuel for international flights (called “international bunker fuels” in the EPA report) is excluded from official national accounts that are most commonly cited. For the statistics above, we included these international jet fuel amounts. This is a sensible approach, counting U.S. amounts for international bunker fuels in U.S. estimates (and, appropriately, excluding international amounts for fuels on incoming international flights). All data and computations for this post are shared in a public spreadsheet with citations.

No major U.S. environmental organization has a substantial campaign of any magnitude addressing aviation demand and rising aviation emissions. There are many initiatives related to offsets, but no large initiatives related to actual in-sector aviation emissions. Aviation is the most neglected of the large emissions sources for U.S. greenhouse gas emissions.

Aviation demand trends are dangerous, presenting a grave risk that the good we attempt to do in other sectors will be swamped by rising emissions in aviation.



March 2019 Update

First, with Nives Dolšak and Aseem Prakash from the University of Washington, the #flyingless co-organizers Joe Nevins and Parke Wilde published an op-ed in The Hill this month.

To some extent, universities already recognize that they need to act on climate change. Following the initial University Presidents’ Climate Leadership Commitments more than a decade ago, there are now more than 600 university climate leadership commitments, of which 372 appear to promise some sort of “carbon neutrality” by 2050. The related university reports are full of admirable measures on recycling, food service, building codes and electricity efficiency. But these commitments neglect critical sources of university-related emissions such as aviation….


Some might say that academic travel has so little impact on climate change and the cost of curbing it is not worth the damage it might inflict on research. This is a self-serving position which undermines the moral commitment of academia to fight climate change. Every group that is asked to reduce carbon emissions probably believes that their activities are too important — either for their own survival or for humanity — to sacrifice at the altar of climate change. If people in Appalachia or the Navajo nation in Arizona, which face extreme poverty, are asked to sacrifice their livelihoods in the coal industry, what moral right do academics have to disavow their moral responsibility of responding to the climate crisis?

Second, from the inspiring and informative presentation by Dr. Kim Nicholas of Lund University at our February 2019 webinar, we have the full slides and video of selected highlights.

Third, we celebrate reaching 600 academic supporters for our #flyingless petition initiative. On our Twitter feed @flyingless, you can find links to dozens of new developments each week in aviation policy, personal experiences with ground travel, climate research, university sustainability, and #ClimateAction. Please continue to share this initiative widely.

Feb 7 2019 #flyingless webinar (with Dr. Kim Nicholas)


  • Welcome
  • Dr. Kim Nicholas, Ph.D., Lund University: “Innovations and progress in flying less.”
  • Network update: (a) inviting academic supporters for the #flyingless petition initiative, (b) brief reports on what you have been doing and how we can help publicize.
  • Closing

Notes: webinar will be recorded to allow future viewing. See for information about the petition initiative, a list of academic supporters, and frequently asked questions (FAQ).

Mechanics: We have found cross-continental conversation is easy and convenient, but with a couple quirks. WebEx login is enabled 15min in advance, allowing time to test audio. In our experience, best audio options are headphones/mic with good internet connection or convenient telephone call-in number (built in laptop speaker/mic sometimes less effective). To avoid echo, have only one mic open in a room, and place mic where it does not pick up too much audio from speakers. Use on-screen mute function when not speaking (and also pls be understanding if we might need to mute folks when not speaking). For any trouble-shooting, if your audio is not working, use the on-screen text chat function and another participant may be able to help.

Hosted by Parke E. Wilde

Feb 7, 2019.

Thursday 12:00 pm | 1 hour | (UTC-05:00) Eastern Time (US & Canada)

Meeting number: 735 876 716

Password: 3TGhjR82


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You can also dial and enter your meeting number.


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+1-617-627-6767 US Toll

Access code: 735 876 716


A photo from our more informal social event Dec 30 with people in the U.S., UK, Finland, New Zealand, and Sweden (also including Kim Nicholas). video here