New Saxifrage chart on flying and other transportation

For scientists and climate activists who think about transportation and the climate emergency, the graphics produced by Barry Saxifrage for his website Visual Carbon and for the National Observer are a delight.

One of my favorites for many years has been his comparison of greenhouse gas emissions per mile (or per km) for different transportation modes. Late last year, I asked Barry about train estimates in particular, because Amtrak is electrified in the northeast where most Amtrak trips take place, while the carrier uses diesel on long-distance routes elsewhere. Kindly, Barry has revised his graphic to include this distinction, while also updating the numbers. Truly committed to climate action, he freely shared the updated charts this week.

Let me briefly list some of the unique features for readers who study this issue closely: (1) he clearly shows the heavy emissions from flying, (2) he includes a factor for non-CO2 impact of flying (in red circles), but he also provides alternate estimates for readers who prefer to exclude this radiative forcing factor for consistent comparison across modes (in clear circles), (3) he shows emissions per mile on the ruler at bottom or alternatively miles per ton of emissions on the ruler at top, (4) he provides green, yellow, and red color coding to make it easy to see which modes are most harmful, (5) he shows how automobile emissions per passenger mile depend on the number of passengers, which is a common source of confusion in comparisons across modes, (6) he has tiers for fossil fuel vehicles and electric vehicles, which focuses our attention on the critical climate action strategies of rapid electrification and rapid greening of the electric grid, (7) most importantly for this field of science communication, he has a thorough data footnote.

Due to data limitations, Barry had to exclude embedded emissions for vehicle production, but he applied this approach consistently across modes.

The chart helps for understanding a major theme of our #flyingless initiative:

For institutions and individuals, an initiative to reduce flying will have two important effects: (1) it will reduce miles traveled and (2) it will reduce emissions per mile with almost all mode substitutions.

You can download the full graphic in miles and kilometers formats. I hope this graphic is widely shared on social media when there is a muddled discussion of how flying compares to other modes of transportation.


A #flyingless social event Dec 30

Please join us for the second annual #flyingless New Years Eve Eve party online Dec 30 at 3pm eastern USA time (8pm UK time, 9pm Western Europe). It was fun last year, and we are expanding this year.

We will have short speeches and toasts on themes of effective work and joyful living without flying. For the many people around he world taking a #FlightFree2020 pledge, this event may serve as a conversation starter in advance of New Years Eve parties the following night.

See below for technical details about how to participate.

Many of the participants come from our vibrant international Twitter community:

  • Myself, Parke Wilde, at Tufts (@flyingless) and Joe Nevins at Vassar College (@jonevins1), the co-organizers for the university #flyingless petition initiative. The Boston party may also have greetings from Shoshana Blank in the Tufts Office of Sustainability (@GreenTufts) and Janie Katz-Christy of Green Streets. Email us ( for location details if you would like to attend in person in Boston.
  • #FlightFree2020 organizers around the world including Maja Rosén in Sweden (@flygfritt), Ariella Granett in the United States (@FlightFreeUSA), and Anna Hughes in the UK (@FlightFree2020).
  • Kimberly Nicholas (@KA_Nicholas). Lund University. Sweden.
  • Peter Kalmus (@ClimateHuman). California. Organizer of the inspiring No Fly Climate Sci site and author of Being the Change: Live Well and Spark a Climate Revolution.
  • Genevieve Guenther (@DoctorVive). Leader of End Climate Science. New York City.
  • Aarne Granlund (@AarneGranlund). Climate mitigation professional. Finland.
  • Kim Cobb (@coralsncaves), a climate scientist and environmental leader, and Blair MacIntyre (@blairmacintyre), an innovator in virtual reality social connections with Mozilla Hubs. Georgia Tech. Atlanta.
  • Larry Edwards (@RadReduction). Sitka, Alaska. A contributor to Stay Grounded.
  • Roger Tyers (@RogerTyersUK), who took a train from the UK to China this year.
  • Joshua Spodek (@spodek), who discusses flying less in a TedX talk.

After initial toasts from these folks, we will open the event up for additional participants if feasible (it partly depends on the number of participants). WebEx also has a chat window for additional conversation.

If you would like a food element to connect across the sites, consider this vegan cookie recipe from the wonderful cookbook author and #flyingless supporter Linda Watson (@cookforgood).

To make it a party, consider inviting some friends to this event and choosing a location that has some local visual meaning or “sense of place.” For example, our Boston event will have window views of the Boston skyline and harbor in the late afternoon.

In addition to being a party, this event is practice for enhancing the social components of our ongoing initiative to develop linked simultaneous multi-site conferences. Please send comments and feedback afterwards.

We hope you enjoy this experiment in long-distance socializing! Sometimes I think that academics would be quite willing to give up most of their flying, if only we were assured of still being able to have a drink with our friends. In a time of climate grief, perhaps we should give this lots and lots of practice.

Technical details: Connect using this WebEx link. There are multiple audio options. Please mute when not speaking, and (to avoid feedback) never have more than one mic open in the same room. The webinar will be recorded, so we can make a video for sharing with people who cannot attend. You can use the WebEx chat window for troubleshooting as well as socializing. The most common difficulty is connecting WebEx with your computer’s mic and audio. There will be a WebEx practice session 2 hours before the main event. 

Public comments on the ICAO aviation offsetting scheme

Here is the cover letter for my public comment on the International Civil Aviation Organization (ICAO) offsetting scheme, called CORSIA. The UN agency has received 14 proposals for offsetting programs, and seeks public comment on whether they satisfy evaluation criteria. Perhaps the most difficult criterion, which the proposals I read do not meet, is the additionality criterion. I first heard about the open comment period yesterday.

Dear ICAO:

Here attached are my public comments on the first 5 of the 14 offset proposals (ordered alphabetically). Insufficient time was provided in the public comment period for me to read the remaining proposals.

The due date for comments is Sep. 5, and the first notice I can find announcing the open comment period, anywhere on the internet, is Sep 3. Because the ICAO website does not give an opening date for the comment period, and the ICAO Twitter feed does not contain any announcement of the comment period, I can find no evidence that this comment period was longer than 2 days. Clearly, this is not proper procedure.

Overall, the approach to additionality is not credible. Every sector of society is rapidly paying more attention to the climate crisis. Across the board, the baselines used in these proposals take insufficient account of future actions by external actors (outside of the offset scheme) that will simultaneously be seeking to affect emissions.

To give just one example, suppose an offset program funds fuel-efficient wood stoves to replace open cooking fires in a low-income country. The proposed “additionality” certification states that, in the absence of the offset program, households would continue to cook on open fires. The full emissions reduction from the change to new stoves is credited to the offset program as “additional.” But this is not plausible. In a time of climate crisis, countries around the world are rapidly expanding electrification, and the electric grid in turn is relying more on renewables. Rural people in low-income countries are moving by the millions to cities, where they are more likely to have electricity. To assume the households would all continue using cooking fires is not plausible. So the offset scheme gets credit for far more emissions reduction than was in fact achieved.

This problem is pervasive in the proposals I read today.

Here are my comments in the format of your official rubric, on just 5 proposals, but but my public comment greatly understates the deep emptiness of this offsets approach.

What really is needed from ICAO and CORSIA is actual emissions reductions within the aviation sector. It is a travesty that ICAO only provides overall goals for emissions “net” of offsets, and will not state goals for actual emissions reduction in the aviation sector.


Parke Wilde

Among the 14 proposals, the Clean Development Mechanism (CDM) sent what appears to be a cover letter. I could not find any proposal in the required format. The cover letter did not mention the additionality criterion, as far as I could tell. The CDM’s ability to deliver additionality has been criticized in the past: How Additional is the Clean Development Mechanism?