What is your initiative’s objective?

In a time of climate emergency, we seek to persuade academic communities to set goals and measure progress for reducing their greenhouse gas (GHG) emissions, in line with the recommendations of scientific authorities such as the Intergovernmental Panel on Climate Change (IPCC). Aviation is responsible for a large fraction of total emissions in universities and research institutions, so we call for rapid reductions in total flying, while preserving the good we do in the world and the joy of being an academic. Universities and research institutions have a high-profile public role, so our example sets the tone for larger economic sectors and more powerful political decision-makers. Academic communities should treat the crisis like a crisis. Our Travel Petition has specific actions for universities, professional associations, research funders, and individual academics (including faculty, students, and staff).

How large is the impact of aviation in university and research institutions?

Aviation is responsible for more than 25% of emissions for some institutions that have measured their emissions accurately, which makes aviation the single biggest emissions sector. This sector deserves a central place in university communications and plans for climate mitigation. In a study at the University of British Columbia (UBC), Wynes and Donner (2018) estimated that aviation emissions (including direct CO2 emissions from fuel burn plus an indirect radiative forcing factor) were responsible for 63%-73% of UBC campus emissions; Arsenault et al. (2019) estimated emissions for the University de Montreal at 30%; ETH Zurich (2019) and (2022) estimates that aviation emissions (part of “Scope 3”) were 18,000 tons of CO2e, compared to under 9,000 tons of CO2e for combined direct campus emissions under Scope 1 and purchased goods and services under Scope 2 [edited for precision May 18, 2023]. Air travel represents 35% of greenhouse gas emissions at the Swiss Federal Institute of Technology Lausanne, 30% at UC Santa Barbara, and just under 50% at the University of Basel [added May 18, 2023]. Many universities understate aviation emissions, either excluding them as “Scope 3” emissions outside of university control or counting just selected flights (such as flights booked through particular official travel agents). Our Travel Petition calls on universities and professional associations to measure aviation emissions in full, so more precise statistics will be available in the future (and we will update this FAQ item).

Why do some people publish lower estimates for aviation impact?

Many methods are employed to understate the measures of climate impact that are most relevant for university and research communities (Wilde, 2019). Writers may do the following:

• report just the jet fuel burn, even though the full life-cycle impact of aviation is much higher, due to emissions from making airplane vehicles, cement to build airports, fuel for ground vehicles, the energy used to extract and transport the jet fuel, and so forth;
• report just the CO2 effects, even though the radiative forcing effects related to contrails and other non-CO2 effects are greater;
• report global estimates for the percent of total GHG attributable to aviation, even though higher percentages for high-income countries and for high-flying economic sectors such as academia and research are more relevant.

With GHG emissions, there are several reasonable methods for consistent accounting. For example, the Saxifrage (2020) graphic below consistently compares emissions from vehicle operations without counting the full life-cycle emissions of the vehicles themselves. Others consistently compare the full life-cycle impact of different modes. In contrast with these consistent accounting methods, it would be misleading to count merely jet fuel burn in the numerator, just for aviation alone, and then report the resulting percentage as the impact of “flying” in general (Wilde, 2019).

In total, Lee et al. (2021), whose research is used by the IPCC, estimate that flying is responsible for approximately 3.5% of total global human impact on the climate. The relative contribution of aviation is much higher in comparatively high-income countries, and higher again in comparatively high-flying sectors such as academia and research. If your university or research institution wants to treat the climate crisis like a crisis, it should take aviation seriously. As students and many other stakeholders increasingly express high expectations for climate action, people will notice if universities and research institutions avoid frank talk about aviation.

Should I use offsets to mitigate the impact of flying?

No. In a full reflection on this question (Wilde, 2020), we find that some offsets are fraudulent, many offsets overstate their net carbon reduction, bad offsets distort the carbon market by suppressing prices across the board, and we do not need offsets as much as we might think. To give just one recent example of the challenges, hundreds of thousands of acres of forest land that had been counted in offsets burned in U.S. wildfires in summer 2021. In a time of climate emergency, as the general public becomes more educated about offsets, your institution’s reputation will be served better by transparently reporting actual emissions and avoiding offsets.

How bad is flying compared to other transportation alternatives?

Flying is generally much worse. We encouraged Barry Saxifrage, a graphical communicator of quantitative technical information on climate issues, to develop this update to his wonderful comparison chart (now including detail about electric and diesel Amtrak trains, for example). His illustration nicely deals with the most common confusions, for example distinguishing fossil fuel automobile emissions according to the number of people in the car. Don’t be misled by comparisons elsewhere of full airplanes to nearly-empty cars. In truth, when fully-occupied cars are compared to fully-occupied planes, the planes have far greater emissions. Likewise, when average-occupancy cars are compared to average-occupancy planes, the planes again have far greater emissions. Moving rightward in the graphic: fossil fuel buses, electric cars, and electric trains all are vastly better than fossil fuel cars and planes.

Does your initiative support climate justice?

Strongly. Aviation is one of the most unequally distributed and climate-damaging goods and services in the economy. In our vision, comparatively high-income populations will sharply reduce their total aggregate GHG emissions, leaving more space in the carbon budget for the much larger majority of people in the world. Within academia, comparatively senior and comparatively white professionals are responsible for a large fraction of total flights, and we support institutional policies to reduce these flights first.

In Nature Human Behavior, Sarabipour et al. (2021) studied 270 in-person national and international conferences in 2018-2019 and noted opportunities for lower climate impact and more fair access simultaneously: ” We found that many meetings could be improved significantly in terms of diversity, inclusivity, ECR promotion, networking and career development, venue accessibility, and, importantly, reducing the meetings’ carbon footprint.”

Alternatives to flying, including on-line conferencing, do have some disadvantages for some young scholars, but they have great advantages for many others, including scholars with lower incomes, residence in lower-income countries, and with parenting and elder-care responsibilities that hinder travel. On balance, our initiative supports a more just vision of academic life.

How can researchers reduce their flying without impairing their work?

Consider a multitude of options. Not every option will be right for every scholar. Add new options to a list of your own. It is tempting to focus on the options you like least, but we encourage you instead to focus on the options that work best for your setting. 

• Increase research and writing time instead of traveling for work.
• Attend some meetings and conferences less frequently, while maintaining friendships and collaborations remotely between in-person events.
• Reduce flights to lower-value meetings and conferences, which may enhance your work and reputation less than you might think.
• In field research, avoid duplicate travel occasions by staying for a longer time on a single trip.
• Recommend a graduate student or junior colleague to give a presentation in your place. Build your long-term place in the field by advancing the careers of people who trust in your mentorship.
• Plan ahead to work harder on the train or bus while traveling to conferences. Many trains and buses now have WiFi, and, even when internet is unavailable, you may be able to concentrate better without it. Enjoy dedicated bonding time with colleagues from your own university when car-pooling or van-pooling to conferences.
• In the destination location for conferences, plan ahead to visit colleagues at local institutions to strengthen connections that otherwise might have required a separate trip.
• Take full advantage of all relevant conferences, meetings, and visiting speakers that come to your own university’s location. Build your professional network in ways that fully use the travel time that others already have committed.
• Encourage your professional association to support high-quality remote participation in conferences.

Is it really feasible to have a good academic career with less flying?

Yes. Notice the growing number of academic and research colleagues around you who are visibly reducing their flying, innovating in the area of conference design, monitoring the GHG profile of their institutions and professional associations more completely, and calling for more ambitious action from political authorities.

Our mock travel and tourism show, Lifestyles of the NOT Jet Set, provides a window into just one academic’s experience, using examples from co-organizer Parke Wilde’s professional and personal travels in summer 2021, with episodes from eastern Massachusetts, Rochester, Austin, Memphis, and Chicago.

Is my decision to fly irrelevant, because the plane would have flown anyway?

Nonsense! Some have argued that the marginal carbon footprint from flying is zero, because the plane would have flown anyway, but this is a fallacy. The airlines are not in the business of flying empty planes, so somebody must have provided the economic demand that supported the scheduling of each flight.

There are two equally sensible ways to look at this question, both of which lead to the conclusion that the best estimate of personal carbon emissions from flying is the average emission per passenger on the flight (which is a large positive number).

• We could simply attribute the flight’s carbon emissions equally to each passenger on the flight. This leads directly to the conclusion that each passenger’s carbon impact equals the average emission per passenger.
• We could instead consider the marginal impact of each individual passenger. For many passengers, this marginal impact could be quite low (related merely to the additional fuel required to fly one more passenger). For some critical passenger, who tipped the balance of the airline’s business calculus in favor of scheduling the flight in the first place, this marginal impact would be very high (most of the emissions from the flight). None of us knows which passenger tipped the balance. So, to compute our expected climate change impact, we have no better option than to draw on statistical probability and use the expected value of our marginal impact. Taking the average over all the passengers, including the one passenger with the big impact and the many passengers with the small impact, the best estimate of expected personal carbon emissions is once again the average emissions per passenger on the flight.

More generally, Bigazzi (2019) has the best technical analysis we have seen on marginal impacts of different travel modes. Compared to the average statistics from Saxifrage, above, the upshot from Bigazzi is that trains come out even better relative to planes.

Is your initiative focused on personal carbon footprints and flight-shaming?

This initiative is focused on institutional change in civil society (academia) as part of a coherent theory of social change, contributing to transformation of bigger economic sectors with greater influence over powerful political decision-makers. We do not care about individual non-flying purity. Our Travel Petition addresses universities and research institutions, professional associations, and research funders. It is true that, after reflecting on the profound ancient philosophical dilemmas of individual action in a social setting, we retain great respect for individual actions to reduce flying, because of their contribution to positive social change. Co-organizers Joe Nevins and Parke Wilde have personally stopped flying for many years, while still pursuing thriving academic careers. This helps us understand in a concrete way the feasible options that academic institutions face. If you feel some personal guilt over your flying, we trust in your introspection to discern whether your feelings are calling you constructively to greater personal climate ambition, or whether they can be ignored. You may or may not choose to endorse the fourth and most personal element of our Travel Petition. What really matters is whether you help our initiative achieve its goals for institutional and political change.

Here is our older Frequently Asked Questions (July 2019).