I just came back from a conference in Palermo, a city located on the Sicilian island in Italy, taking only low carbon transport, travelling more than 4,500 km in total. Through this article, I wanted to share this wonderful experience. I hope that it will inspire you as well, so we can together make academic/business trips more sustainable!

Why not going by plane

I have been flying since I was born in New Caledonia which, being a relatively small island and with family in France and USA, did not leave many options but to take the plane often to travel in other places. Since 2020, at a period I was following my studies in France, I took the decision to stop taking the plane. Although I am unsure if that’s possible for the future to hold such a challenge, I make the maximum to keep doing so. But why?

The plane is a public transport having one of the highest carbon footprint in terms of passenger-kilometre (i.e. equivalent to moving one person over one km). While the footprint is relatively close to driving a thermal engine car (i.e. 218 g CO₂e for car and 188 g CO₂e for plane on average), the impact of flying lies in the increased distance that it permits. Going thousands of kilometres away is made simple, especially considering it is often difficult to compete to price tag and speed. Hence, it is easy to accumulate plenty of kilometres, along with the greenhouse gas emissions (GHG) that come with it.

From my experience, the figure that made me realize the issue was the CO2 emissions reported on the boarding pass of my latest trip from France to New Caledonia (2019), disclosing 1100 kg CO2/person estimation (one way, economy). How could I be responsible for producing such a considerable amount of gas by myself? Even more striking was when I came across the now famous BonPote blog a year after, stating that a round trip from France to Australia would emit approximately 6 tons of CO2 eq¹. Sydney was just a connection for my trip back to home, how come? Now this is no longer possible to keep taking the plane unconsciously, like if it was typical public transport. Over the past few years, it has been more or less easy for me to refuse taking the plane. Those occasions were only related to private life and solved by pushing for local or European trips with friends, where the train was a conceivable option (I also took the ferry to Corsica twice). As time went by, people around me became aware of my self-imposed constraint and accepted it. Like switching to vegetarian diet, it just takes a bit of time for people to get used to your new habits. The situation work-wise was also well suited, my recent positions did not require international travel. However, now that I am conducting a PhD, things have become challenging in respect to the international conference participation system.

More about academic conferences

For the reader who is not familiar with academia and research, fellow researchers and PhD candidates alike are expected to share their findings among the community. They are employed by public institutions (in the majority of the case) and they are expected to make their discoveries publicly accessible as part of their contract. There are two complementary ways to achieve this. One is the publication into peer-reviewed scientific journals. The other way is to go to (inter)national conferences to present in person. These are also the occasion to meet with the top recognized experts of the field. Researchers submit their proposal for presentation or poster based on a short summary with key findings called an abstract, the selection committee receives all applications and selects abstracts justifying original research work that is relevant for the conference. If your abstract submission is accepted, you are expected to present at the conference. Considering the often global scale of research, conferences are led in places which are generally not close to the laboratory, implying trips.

Planning

I identified two relevant conferences and got accepted to both. However, one was in Singapore, which did not let the room for a possible alternative to the plane. Luckily, the other one was in Palermo (Italy, on Sicilian island). The preparation started with a Google Maps, making me realize the 2300 km separating Toulouse and Palermo on land, and that there is no bridge connecting continental Italy and Sicily. Options seemed difficult to find but I was gradually getting a sense of the mains cities from which connections were possible, by leveraging websites like Trainline and Railee. The turning point was when my colleague Damien, who was also planning to attend the same conference, told me that he would also go for low carbon transport. Kudos to him as he recently went to another conference in Goteborg by train from Toulouse. Knowing we were now forming a team with the same objective raised motivation. On top of that, I was recommended to talk to a researcher from Rennes who had recently gone to Palermo by train to attend another conference there. Inspiration from others’ experiences was really a powerful source of motivation, hence this blog post!

We discovered that there is a daily night train going from Rome to Palermo. We initially thought this was a bug on the Trenitalia website before knowing that this InterCity Notte train actually takes the ferry: It is boarded on an on-purpose ship equipped with rails, allowing to cross the handful kilometres separating continental Italy with the Sicilian island, avoiding an additional train and a dedicated ferry connection. This train alone represents a big 900 km direct trip, and it is equipped with comfortable coaches, optimally traveling by night and arriving on time for the beginning of the conference, what a dream! From Toulouse, it was only possible to reach Italy by train via Ventimiglia, implying 3 different trains, which had to be followed by one train to Genoa, then another to Rome to catch the night train. This was going to be a 6 trains trip in total, which was a bit too long and costly. Then we considered taking one direct night bus connecting Toulouse and Genoa (750 km, 45 €, 11h). This final plan was making the trip particularly efficient with one bus and two trains to travel over 2 300 km, especially to an island! We ended up booking our trip, departing Sunday at 11:55 pm and arriving on Tuesday at 12:30 pm in Palermo, which was right on time to have a good Italian lunch in Palermo and start the conference in the afternoon.

The trip

Travel had unexpectedly beautiful views over the Mediterranean all along the way, some were definitely postcard sceneries. Below are some pictures I took from the window. Note that the speed made it difficult to capture the best angles and I certainly missed the best views.

This travel took some time, undoubtedly more than by flying there — let’s not forget about the time it takes reaching the airport and completing the different formalities. Despite this, the train has its advantages, like offering a decent work environment so you can keep track of your project. For example, I have been able to do some interesting bibliography, improving some Python code together with my colleague Damien, but also performing a recap of the very intense conference, based on my pages of notes and dozens of pictures. While most of the time you will find more space, current to charge your electric equipment, Wi-Fi connection or mobile network access, I still advise planning as if it was not the case, therefore downloading and printing resources in advance, properly charge your devices, bring a powerbank. Do not hesitate also carry a pair of earplugs or noise-cancelling headphones as they can prove ideal to isolate yourself from uncontrollable sources of noise. By the way, relax rules regarding the luggage is another underestimated advantage of this kind of transport, as you can often carry more belongings than with the plane.

Talking about price

Speaking of price, to our greatest surprise, our journey costed about 260 € for the round-trip, including the sleeping bed in the InterCity (saved hotel cost). Who could have imagined that I would beat the price of the flight? Yes, we are cheaper (over 500 € for plane alternative)!

Carbon footprint

Now you may be wondering what is the actual gain in terms of avoided CO2eq for this trip, as this was the purpose of all of this anyway. It is estimated to 110 kg of CO2 eq for the roundtrip (44 kg for bus, 12 kg high-speed train, 57 kg of intercity). In comparison, using a direct flight is estimated at approximately 430 kg CO2 eq accounting for non CO2 emissions. In an alternative scenario including a connection in Munich (Germany), which is reference to colleagues, it rises to about 900 kg CO2 eq. Our alternative leads to almost four times fewer emissions than the direct plane, and almost height times less than the realistic option including the connection.

Absolute value is also important to consider here, when by 2050 a maximum average of less than 2 tons will be possible by capita to maintain climate change temperature increase below 1.5 °C. Emitting nearly one ton of CO2 eq for a one-week conference travel, not even accounting for other emissions related to the event itself, makes it hard or to next impossible to comply with an egalitarian share of emissions, apart than considering the participation as having higher priority than other people needs, which can be hard to justify.

More on GHG calculations

• Emissions are reported for round-trip, from Toulouse to Palermo
• Train and bus distance was calculated using Google Maps estimated distance by car, which appeared to be following approximately the same path as the rails.
• Plane’s emissions were calculated as going straight line (quite optimistic assumption)
• Plane’s condensation trails (non CO2 emissions) are accounted for as they contribute to additional greenhouse effect.
• Connection in Germany is considered as separating two different trips. The sum of distancewould make it a long haul flight which shows lower CO2eq emissions per km•passenger. This maybe considers the two take-offs involved and the flying altitude (not sure about that).
• ADEME ImpactCO2 online tool was used to make the estimation².
• Impact of train was adjusted to consider the different electricity mix in Italy, which is about 5x more impactful as compared to France according to Ecoinvent 3.11 cutoff³.

We need you as well

I do not intend to blame anyone taking the plane with this post, it is just a contribution to raising awareness among the academic community and more generally for professional and personal travels by plane. Doing this kind of “personal” action with a couple of colleagues is a good step forward, but it will remain clearly insufficient, the expected change in society to reach climate goals is huge and every citizen and organization have to be involved. That is the reason why writing and publicly sharing this experience was probably the most important step of this trip.

Budget-, time- and effort wise, attending conferences or travelling in general cannot be kept at the same pace as when flying was still an option. In fact, it will be necessary to make more thoughtful decision. While this time we managed to beat the price of the plane option, there will be many situations where it would be impossible to reach the travel location with an acceptable time and financial budget. We will need to ask ourselves if the travel is really worth it, and we would probably have to refuse some “opportunities” to only go for the most relevant ones.

One very positive personal outcome that may be underestimated with this kind of action is the happiness of achieving a meaningful challenge that makes you proud of yourself.

This was my first experience of low carbon international travel for work, feel free to offer any suggestions. I would be happy to read your personal experience, even the less enjoyable ones.

Acknowledgments

I am grateful to Lorie Hamelin, my PhD supervisor, who made all of this possible!

References

1. https://bonpote.com/en/train-vs-plane-second-round/ ↩︎
2. Official ADEME simulator. Beware that most of the data apply to French context. Available in English: https://impactco2.fr/outils/transport ↩︎
3. Ecoinvent (2024) “ecoinvent Version 3.11.” Available at: https://support.ecoinvent.org/ecoinvent-version-3.11 ↩︎

Useful links:

• Bastien’s experience : https://www.linkedin.com/posts/bastienpais_scientific-research-mobility-and-activity-7259223153300664320-C7Za/
• Natacha’s experience:  https://www.linkedin.com/posts/natacha-gondran-b022ab17_ne-plus-prendre-lavion-cela-semble-une-activity-7328110620971610113-S77q
• Article about researchers flying less: https://www.nature.com/articles/s42254-022-00523-6