This page describes how the organization committee handled the topic of sustainability and eco-responsibility during useR! 2019, why and how decisions have been taken. The intent is to provide a comprehensive feedback to the community on this topic and to share a few learned lessons to pass to the next organizers. Some comments are my personal opinions and do not oblige the entire organization committee.

As learned from a previous experience in which a full carbon footprint has been estimated (the national conference JOBIM 2013, 450 participants), 46% of the conference carbon footprint was due to plane transportation of the participants. In the same line, the carbon footprint of a complete science making process is evaluated in this article: the contribution of the mobility represents 75% of the total carbon footprint of the monitored PhD. The relative impact of transportation in the conference carbon footprint is expected to be even larger for an international conference than for JOBIM so we chose to restrain the estimation of the carbon footprint of useR! 2019 to that sole component, which is the easiest to estimate.

From a methodological point of view, the estimation was based on a self-declaration survey in which the city of origin, as well as the mean of transportation is collected. Based on an estimation of a bit more than 20 % of the participants, we computed partial carbon footprints for the main geographic areas using an automatic localization of the cities. First, the GPS coordinates of all cities were extracted from the GeoNames database to compute the geodesic distances of each travels. Then carbon emissions were estimated using the ADEME emissions correspondences tables available at this link. The obtained total was adjusted by geographic areas (using a post-stratification approach) to obtain a final estimate. This gives the total value of 864,406 kg eq. CO2 (25,911 for France, 214,874 for Western Europe, 51,094 for the rest of Europe, 298,777 for North America, 50,718 for Asia, 198,002 for Oceania and 25,030 for South America for, respectively, 240, 557, 70, 97, 29, 27 and 6 participants registered1). Note that this value is probably an underestimation of the true value since people tend to self-declare more easily if they are already sensitive to the topic of carbon footprint impact of transportation. In average, a useR! participant emitted 720 kg eq. CO2 for transportation, which represents 15% of his annual carbon budget according to the IPCC objectives to limit the temperature increase even further to 1.5C (see this reference).

As a very personal note, I think that it is our responsibility, as scientists, to start thinking about the impact that the organization of conferences (and more precisely our transportation to attend conferences) has on the environment. At the current time, there is no real alternative solution and I am as guilty as anyone of frequently using the plane to be able to discuss with colleagues, organizing projects, going to conferences, … In addition, note that at useR!, we did not have any concrete action to alleviate that impact. However, I believe that providing facts and figures is a first small step to start the process of thinking about actions that can truly matter.

In addition, several participants have expressed the fact that the lunches were the sources of too much waste. That is entirely true (whereas, as explained before, the impact of this problem is negligible compared to the impact of our transportation; I don’t want to say that we should not have addressed it in a better way, just that we should prioritize the two topics differently). I shortly explain the global constraints that we faced and how we tried to take responsible decisions regarding these aspects:

• the question of the wastes in terms of dishes was posed very early in our organization committee but there were only a few number of choices. The number of caterers that can handle a daily lunch for 1200 people is very limited and none offered an option of reusable dishes in Toulouse. We contacted Element'erre to at least provide ecocups (lent to the participants) but we only did that too late and the solutions proved to be too difficult to manage for 1200 participants (Element'erre is a service that take back all the cups everyday to wash them so we would have needed to make sure that everyone brings its cup back, which proved really difficult to handle with that many participants);
• we then had to weight the option of having lunch boxes against the one of having a buffet. The second would have led to less dishes wastes but, in addition, we would not have been able to give the food leftovers to an association for homeless and persons in needs. The choice has been made of more dishes wastes for less food wastes. This is a personal decision against anyone could argue but I still think that we were right to do that. Approximately 200 meals have been given every day to persons in needs, instead of being thrown away;
• to better handle the waste of plastics and bags, we contracted with easytri that performs selective sorting of wastes and reuses the collected trashes. Selective trash bins have been installed in the conference center (but they were probably under-advertised and under-used). One of the problems that we faced with this solution is that we were not able to obtain a trash bin for every type of wastes (especially not for the paper bags that would have been easy to recycle);
• Other solutions could have included asking participants to self-declare the meals they really wanted to take (but from a previous experience for Journées de Statistique de la SFdS, this proved highly inefficient: most people simply don't answer to that type of request, or answer and change their mind) or to ask people to bring their own cup/reusable bottle… (but we already gave a try at the BYOL initiative, and still had to provide a very high number of lanyards at the last minute since less than half of the participants brought their own).

In conclusion, we certainly not succeeded to tackle the problem in the best possible way but that was a constant concern for us. This is also the main reason for which we provided local and perishable goodies. From our experience and what we learned, the best advice that I could give for future conferences would be to have someone dedicated to that only issue from the start. The reason is that, as an organization committee, you have already too much to think about. Sustainability is certainly not a critical point to make the conference happen: it is something that, as human beings, we think is important. The only solution to have a more effective way of handling the problem would be to have someone having only that topic in mind and supporting the others on their respective topics to take the time to investigate all solutions and find the best one.

Nathalie Vialaneix
on behalf of the organization committee