Climate Change Opinion

Should AGU Have Fly-in Meetings Anymore?

Should members of the American Geophysical Union “walk their talk” by cutting carbon emissions related to meeting travel?


The American Geophysical Union’s (AGU) Fall Meeting is the world’s largest international gathering of Earth and space scientists. Last year, nearly 24,000 people gathered in San Francisco, Calif., to attend. This year, about 22,500 people attended Fall Meeting in New Orleans, La.

To satisfy my curiosity, I undertook a study in 2012, a year I happened to attend the meeting, to estimate the carbon contribution of all this air travel to and from the meeting. In 2012, 21,702 people gathered for the meeting. I expected that the contribution would be vanishingly small, given that the anthropogenic production of carbon dioxide (CO2) from fossil fuels in 2010 was approximately 30 gigatonnes [Intergovernmental Panel on Climate Change (IPCC), 2014]. The contribution was more significant than I expected.

Attendees’ air travel to and from this meeting was responsible for more than 5 millionths of total global carbon emissions, even though these attendees accounted for 3 millionths of the global population. How can AGU “walk its talk” on environmental stewardship when participation in its annual meetings requires such carbon-intensive travel?

Context and Caveats

AGU’s leadership in discussions of anthropogenic warming is evident from published research by its members and the organization’s position statements on climate change. The impact of the meeting on CO2 emissions has never been estimated.

I estimated CO2 emissions for each conference presenter’s airline travel to and from San Francisco (SFO) for a sample of conference presenters. (The data I used are here.) This travel is the only part of each attendee’s travel emissions that I estimated. No attempt was made to estimate CO2 emitted during other activities, such as transportation to and from airports, use of restaurants, hotels, and so on.

Gathering the Data

The AGU 2012 Fall Meeting had 1,739 technical sessions, excluding Union and town hall sessions. I sampled 37 of these sessions (2.1%) as follows: Each session was assigned a unique number from 1 to 1,739. I used a random number generator, based on atmospheric noise, to choose 37 numbers. The session corresponding to each number was included in the sample set.

The random sample did not include sections on Atmospheric and Space Electricity (AE), Cryosphere (C), Earth and Planetary Surface Processes (EP), Earth and Space Science Informatics (IN), and Public Affairs (PA). These five sections held 13% of all sessions. As measured by the deviation of the percentage sampled from the percentage of total papers, Biogeosciences (B) was the most undersampled (1 session sampled out of 135) section, and Geodesy (G) was the most oversampled (4 out of 39).

Each presentation had a designated presenter. I assumed that the designated presenter gave the presentation, and the presenter traveled directly between SFO and an airport close to her or his home institution. The effect of this assumption is to underestimate the total travel because it is likely some traveled elsewhere in the same trip, and airline connections were not considered. Other simplifying assumptions included that presenters traveled to SFO from the largest city near their home institutions via a great circle route and that presenters from northern California did not fly. I used various online resources to obtain airport information and determine distances.

Calculating Emissions

Carbon dioxide emissions were based on fuel consumption for different types of aircraft and distances flown, and the “share” of consumption by each passenger was based on the passenger capacity of the aircraft. A number of online emissions calculators for airline flights are available, but they give inconsistent results and do not explain the derivations, hence the methods used here.

I made simplifications that included the following, with values derived from a variety of industry websites:

  • Middle values of fuel consumption for each type of aircraft were used, with the following assumptions:
  • Long-range jets (Airbus 380 and Boeing 747) were used for flights from destinations outside North America and from Alaska.
  • Middle-range jets (Boeing 757) were used for flights from eastern and central North America and Mexico.
  • Short-range jets (Boeing 737 and Airbus 320) were used for flights within western North America except Alaska.
  • I used middle values for cruise speeds of long-, medium-, and short-range jets.
  • I used middle values for passenger capacity for each type of aircraft.

Much more detailed information is available from a variety of sources. For example, the European Environment Agency’s report on aviation distinguishes the landing and takeoff phases of flight from the cruise phases; I used consumption rates only for the cruise phases.

A value of 2.55 kilograms of CO2 emitted per liter of jet fuel (kg/L) was used. Fuel consumption is reported in pounds per hour, and jet fuel expands and contracts substantially with temperature and is subject to a wide range of temperatures during flight. Therefore, fuel consumption volume must be converted to weight. For this study, volume was converted to weight at 15°C (standard temperature); jet fuel weighs 0.8 kg/L.

Presenters from 36 countries are represented in the sample. Of these, 24.4% were from Europe (including western Russia), 13.9% were from Australia and Asia, 0.6% were from the Middle East, 0.6% were from Africa, 1.4% were from South America, and the remaining 59.1% were from North America (including Hawaii). Of the latter, approximately 4.7% were from Canada, 0.3% were from Mexico, 52.8% were from the lower 48 U.S. states, and 1.4% were from Alaska and Hawaii.

In total, presenters in this sample accounted for the emission of 257 tonnes of CO2 during their flights to and from SFO. These presenters represented 1.7% of all presenters at the meeting. If the geographic distribution of attendees is the same as that of the sample, all attendees (21,702) accounted for the emission of 15,493 tonnes of CO2. The assumption of geographic distribution probably results in an overestimate because it is likely that a higher proportion of attendees who were not presenters were from northern California.

Annual total anthropogenic emissions of CO2 (not CO2 equivalents) is about 30 gigatonnes [e.g., IPCC, 2014]. At that level, AGU presenters accounted for 5 millionths of total global anthropogenic emissions from fossil fuels in 2012.

Reasons for Meetings

Attendees at the American Geophysical Union’s 2017 Fall Meeting, this year in New Orleans, La., crowd the poster hall.
Attendees at the American Geophysical Union’s 2017 Fall Meeting in New Orleans, La., crowd the poster hall. Roughly 22,500 people attended this year’s meeting. Credit:

Other attempts to calculate the carbon footprints of large conferences (e.g., United Nations Climate Change Newsroom and Programming Languages Enthusiast) reveal a similarly large footprint compared to the population in attendance. In light of this, some debate exists whether fly-in conferences should be held at all [Parrish, 2009; Environmental Humanities Center, 2017]. The discussion goes to the question of the purpose of a scientific meeting.

Scientific meetings are not held solely to present scientific findings. Indeed, scientific meetings can be argued to be the least efficient means of disseminating scientific results because attendees cannot possibly see all presentations, even in their fields of study.

However, scientific meetings do provide opportunities for face-to-face interaction, which enhances the exchange of ideas. An informal poll of my colleagues revealed that the social interactions—handshakes, hugs, friendly competition, and brainstorming—are the main thing they would miss if they could not attend meetings in person.

The value of these interactions has been assessed for one meeting as a part of the development of a carbon-neutral meeting model. Although the loss of face-to-face contact was the primary concern of the study, only 20% of the participants regarded it as a significant shortcoming.

For large meetings like AGU’s, face-to-face contact is limited by the sheer size of the meetings and the tendency for attendees to gravitate toward people they already know and with whom they already efficiently collaborate by electronic means. Large meetings are inefficient for maintaining social connections for the same reason they are inefficient for networking: There are simply too many people.

Other considerations include whether vacating seats on scheduled flights would make a difference. Greenhouse gas emissions by air transport have been estimated at 1.6% of the world total [Herzog et al., 2005]. Business travelers represent about 12% of air travelers (although, interestingly, they provide 75% of airline profits). An even smaller fraction of passengers would be travelers to AGU meetings. Typical load factors (percentage of passenger seats occupied) for airline flights are currently 82%–84% according to the U.S. Department of Transportation, which is high enough that flights would likely be profitable even if AGU members stopped traveling to Fall Meetings.

Beyond Flying In

Although 5 millionths do not sound like a big contribution to the world’s carbon footprint, we must bear in mind the very narrow focus of this estimate—air transportation to and from a single scientific meeting in a single year. AGU prides itself on being a leader on the issue of global warming, and many sessions are devoted to the consequences of anthropogenic CO2 emissions and related topics. Does the current form of the Fall Meeting detract from this message?

Whether dispensing with fly-in AGU meetings would have a significant effect on carbon emissions is almost beside the point. AGU’s leadership role compels it to act as an example to the community. By leading the way, the initial small effect of its actions could be multiplied, encouraging enough other organizations to dispense with large meetings and perhaps reducing business travel enough to influence airline scheduling.

Thus, I suggest that AGU consider moving with appropriate haste toward using current and developing technologies for its meetings and eventually end fly-in meetings. AGU already provides video access to a few sessions, but the presenters in most cases are at the meeting, and the video is for people who cannot attend.

AGU puts a lot of effort into warning society about the dangers of anthropogenic warming. Given the gravity of the problem, are the social connections for 3 millionths of the world’s population really so important? Shouldn’t we be willing to give up these meetings for the good of society? Paraphrasing Rabbi Hillel the Elder, “If not us, who? If not now, when?”


I am grateful to two anonymous reviewers for constructive comments and for calling my attention to some of the cited websites.


Environmental Humanities Center (2017), A nearly carbon-neutral conference model, white paper and practical guide, Univ. of Calif., Santa Barbara,

Herzog, T., J. Pershing, and K. A. Baumert (2005), Navigating the Numbers: Greenhouse Gas Data and International Climate Policy, 8 pp., World Resour. Inst., Washington, D. C.

Intergovernmental Panel on Climate Change (IPCC) (2014), Climate Change 2014: Synthesis Report, Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Geneva, Switzerland,

Parrish, J. T. (2009), A field geologist looks at a digital world, GSA Today, 19(1), 4–6,

—Judith Totman Parrish (email: [email protected]), Department of Geological Sciences, University of Idaho, Moscow

Citation: Parrish, J. T. (2017), Should AGU have fly-in meetings anymore?, Eos, 98, Published on 21 December 2017.
© 2017. The authors. CC BY 3.0
  • Anthony Mannucci

    I cannot reach the same conclusion as the author. My calculation suggests that the meeting consumes 0.5 millionths of the yearly total for 2012, not 5 millionths. In other words, the author seems to have overestimated the carbon footprint of the meeting by a factor of 10. The calculation is: 15493.0/30.0e9 = 5.16e-7.

  • Anthony Mannucci

    This article does not take into account that one can purchase carbon offsets to reduce the footprint of the travel. For example, United Airlines offers this in their “global citizenship” program. If most AGU attendees took advantage of creating offsets, that would significantly mitigate the carbon load of the meeting. Perhaps AGU itself could offset the carbon load of the meeting by donating to wind farms, planting trees, etc.

  • dgaren

    Why do my posts disappear from this comment stream when I log in with Google?

  • dgaren

    Hmm, my comment is gone. User error in submitting it, or editing/censorship? If the latter, it is disappointing to me that someone must have felt that my comments were either irrelevant or rude. Oh well.

  • LuAnne Thompson

    Thank you very much for your analysis and for helping to foster a discussion about our role as scientists in setting an example for society. I am embarrassed to say that while I have been echoing many of your arguments for years to colleagues, I still fly to meetings regularly. When I talk to colleagues about the challenge of engaging remotely with others, they often argue that it will not be as good as being there in person. I have to agree with them on this point, but as individuals, air travel is by far and away the biggest component of our carbon footprint. And while I also agree with other commenters that changing our culture would negatively impact the younger generation, we need to figure out how to make remote interactions as good as possible, even if it fall shorts of the ideal. As geoscientists, we all know that following an emissions trajectory to keep the climate below the Paris targets will require changes in many aspects of our society, some of which will not be welcome. But we also have the knowledge in hand that not acting aggressively on emissions reduction now will lead to a future that we don’t want for our students and children.

  • totalastronomy

    I have long thought that airline travel (of any length) is too lightly taxed by most jurisdictions. If taxed at the same %age as hotels, restaurants, motor fuel, ski lifts, movies, and so on, the volume of traffic would surely go down. And don’t even get me started on cruise ships, where the passengers are paying essentially no tax whatsoever for high life on the ocean waves. and are subsidised by dirt poor wages for the crew down on Decks B and C..

  • dgaren

    I am glad to see someone publically posing the uncomfortable question, which I would rephrase as: To what extent should scientists and others concerned about climate warming reflect that concern in their own personal choices and behavior? The quote at the end of the article says it all — if not us, then who will lead the way by example? Or is it too much to ask of people, scientists included, to make personal sacrifices and changes in behavior to reflect their values?

    Flying is only one of the carbon impacts of conferences. I last attended the AGU Fall Meeting two years ago in San Francisco and saw several things that disturbed me with respect to energy usage and ultimately the carbon footprint. For example, one display from NOAA or NASA had the biggest, baddest array of huge electricity-sucking monitors I have ever seen, showing satellite image animations or something. It was definitely cool and impressive. But, really, this from a scientific agency that warns people about the threats of climate warming? Do they not care enough about it to voluntarily limit their electricity usage? I also saw essentially everybody using the continuously-running escalators and nobody using the stairs to get down to and up from the poster session room. Why shouldn’t able-bodied people climb stairs? The default “normal” arrangement, promoted by the very structure of the stairway, is for people to use the escalator, with only a very few eccentrics like myself climbing the stairs. In an era when we should be conserving energy, the “norm” ought to be for people to climb stairs, and only those physically incapable of climbing stairs should use (non-continuously running) escalators or elevators. Finally, I wonder what is the carbon footprint — in terms of both electricity consumption as well as the materials used in their manufacture — of all of the laptop computers and smartphones that people had there? Should smartphone usage continue to be “normalized” by encouraging people to download the latest app and use them to guide their lives? I realize they can sometimes be convenient, but at what cost to the climate and environment in general? (Full disclosure: I do not own or use a smartphone, for these reasons and others, but I do use a small flip-phone, so I am not completely guiltless in this regard.)

    All of these potentially rude comments are simply to point out that there are lots of ways people can conserve energy and materials, if they are mindful and intentional and are committed to aligning their lifestyle with the values they profess. However, it seems to me that there is little open discussion of this rather personal and even philosophical realm among scientists or the general public. I would encourage AGU members and leadership to begin including such considerations in planning meetings as well as to incorporate them in policy statements and practices. This may stretch the boundaries of what is considered valid for science, yet it is where we can also “walk the walk” in terms of making changes to address climate warming.

  • Warren Chen

    Wang-Ping Chen
    There is another component not being discussed here: The enormous amount of money and resources wasted on printing posters that typically is used once. If one looks at the low price of good monitors that can be used many, many times, the cost of printing posters is hard to justify. In fact I have attended meetings with hundereds of people where monitors have taken the place of paper posters back in 2001 at Google.

  • Joseph Walder

    I thought people go to the fall AGU meeting because they think it’s really cool to dash from one oral presentation to the next, banging doors and pushing past people who are silly enough to just sit down and listen to an entire session. Since the fall meeting was turned into nothing but narrowly focused special sessions, the opportunities for this sort of behavior have greatly expanded.

  • Jonathan Fram

    I’ve always found regional and subject-area smaller meetings more valuable than the big annual AGU meeting. In-person meetings are important. I have made connections at them that have led to me getting jobs. Perhaps AGU should focus on supporting regional meetings, which would have smaller carbon footprint per participant.

  • Stefan Rahmstorf

    Obviously the number of flights that airlines put on follows demand, so the argument that “the plane would also fly without me” (which my mother used on me back in the 80s) is unworthy of scientists. The appropriate response in my view would not be to scrap all personal meetings, but for all scientists to act in a very restrictive and responsible way with their work and personal travel. Ask yourself twice: is this trip really important enough to justify the damage done by the emissions? That is in fact why this year I attended the AGU Fall Meeting for the second time only – a full 21 years after my first AGU Fall Meeting.

    • Stephen Baines

      I do think the airlines respond to demand, I’m just not sure they respond to the kind of demand that comes from these periodic scientific meetings. They run fixed routes because it is expensive to be more flexible. I can see cancelling meetings as a symbolic or political act meant to convince other organizations to restrict meeting travel more generally. If meetings by groups other than scientists were to follow the lead, then flight schedules to NOLA would change. That would have a much larger impact than calculated here. It also suggests a more outward looking advocacy-based public relations approach. That I could get behind because it is broader based. That’s also why I think increased costs of travel would have a larger effect.

      The argument posed here is more inward looking, concerning personal morality and ethics. To convince ourselves that it’s worth it, we need a real estimate of the net benefits and net losses. If you cancelled the fall meetings, or reduced them in some way, what would the carbon emission reductions really be relative to a null case where everyone stays home? What is the real benefit of these meetings that might be lost? Will more infrequent meetings be more heavily attended? Does that matter? Those issues you could get at I think. Harder to answer would the downsides. How much would education or science suffer? Would public profile of science decline significantly? I actually don’t know the answers.

      BTW. I can’t get to the Fall AGU meetings, and I generally only go to Ocean Sciences or ESA once every two or three years if I have a gaggle of students to support, or a project meeting to organize or attend. I never go to Europe or Asia. I’m more worried about the net effects on science, and particularly students, going forward. I work with some under represented minorities. Seeing science work as a social construct is important for them. Having viable alternatives is critical.

      • Judy Parrish

        I don’t think there’s any question that, if AGU canceled its fly-in meetings, it would have negligible impact. The point I made about that is that AGU is a leader, and if it leads, others may follow. If enough others follow, it could have an impact.

  • Stephen Baines

    I see these estimates all the time, but they leave me wondering about the real net impact of the meeting on fuel use. If the in-face meeting were not to occur, would fuel use actually change? The jets still would fly — these meetings are too sporadic to affect flight schedules much.

    You have to affect the flight schedules to have a real impact on the carbon imprint. The best way to do that is through a carbon tax. Increased costs of travel will necessarily lead to a rethink about the nature of these meetings and the benefits of face to face interactions.

    • André de Rossi

      Only people with lower income (travel grants, if researchers) would ‘rethink’.

    • The airlines definitely respond to changes in demand. Though we might wish otherwise, we can’t think of our flying as “inframarginal” with no impact on flights. For AGU members, you are right to reflect both on conference planning (proximate) and jet fuel tax (distal) policy.