README.md (5941B)
1 This file explains how the carbon footprint of Highlights'25 was computed. 2 3 ## Data collection 4 5 We collected information about the travel plans of participants via the 6 registration form, containing the following fields: 7 8 - Arriving from… 9 - Arriving by… 10 - Leaving to... 11 - Leaving by… 12 - Other scientific activities during your stay 13 - I am planning to attend the Highlights Collaborative Research Week (September 6 – September 12, no extra fees) 14 15 We only kept participants with status "paid" and with an onsite ticket, we 16 arrive at 144 on-site participants. We checked from the email addresses that 17 there are no duplicate email addresses, and from the names that there are no 18 duplicate names. 19 20 We note that the transportation mode was not indicated by all participants: out 21 of 144 participants, 24 did not specify it at all, and 3 more specified it only 22 partially. 23 24 We eliminated participants who were apparently local, and 130 onsite nonlocal 25 participants remain. 26 27 We completed the travel destinations of the participants when missing or when 28 obviously inconsistent, using the location of their affiliation. 29 30 We prepared a file with the following tab-separated fields: 31 - field 0 is the origin 32 - field 1 is the transportation mode 33 - field 2 is the origin 34 - field 3 is the transportation mode 35 - field 4 is the information about whether the participant is extending their 36 trip for other scientific reasons 37 - field 5 is the information about whether the participant is attending HCRW 38 39 (These files are not versioned because they can be considered private 40 information.) 41 42 We run: 43 44 ./generate_trips.py 49.2569809 7.0420618 0.2 45 46 Where the arguments are the latitude and longitude of Bordeaux, and 0.2 is the 47 noise to add. This generates a file trips_anonymized.csv containing, for each 48 trip leg, the mode ("plane", "train", "bus/coach"), the distance (in km, 49 rounded, with noise), and the information about extended stays. A file 50 trips.csv is also produced for debugging (with the data without noise and with 51 personal information). A file map.geojson is also produced with the map of 52 participants and transportation modes and private information (to be used as an 53 image only). 54 55 The file trips_anonymized.csv can then be fed to co2.py which computes the 56 carbon footprint (see below). This gives (from the anonymized data): 57 58 total CO2e emissions (tons): 29.158425 59 for mode plane: CO2e emissions (tons): 26.689530 60 for mode train: CO2e emissions (tons): 2.428939 61 for mode bus/coach: CO2e emissions (tons): 0.039956 62 for distances <2000 km, plane is used for 54/239 trips 63 for distances >=2000 km, plane is used for 21/21 trips 64 flights of over 2000 km account for 15.987136 CO2e emissions (tons) i.e. 54.828531 percent of total for 21/260 total legs 65 distance by plane: 143539 66 num by mode plane: 75 67 num by mode train: 177 68 num by mode bus/coach: 8 69 dist by mode plane: 143539 70 dist by mode train: 65647 71 dist by mode bus/coach: 1427 72 73 Hence, the total CO2 footprint is 29 tons CO2e (it is the same with the 74 non-anonymized file). Around 92% of emissions are due to plane travel, and 55% 75 of the emissions are due to 8% of the transportation legs, namely, 76 the plane trips of over 2000 km. (All trips of more than 2000 km are done by 77 plane) 78 79 The average footprint per onsite non-local participant (130) is around 80 224 kgCO2e. The average footprint per onsite participant (144) is around 81 202 kgCO2e. (These figures are computed from the anonymized data.) 82 83 ### Carbon footprint (unchanged from 2024) 84 85 Like in 2022, we compute the CO2 fotprint following the 86 [labos1point5](https://labos1point5.org/ges-1point5) data, which is adapted from 87 the French agency [Ademe](https://www.ademe.fr/). We use the values from 2022 88 without updating them to ensure that the methodology is comparable. 89 90 - For train, we count **37 gCO2e/pkm** (international train). This is pessimistic in France, very 91 pessimistic for TGV, but similar to the 41 gCO2e/pm for national (UK) rail 92 given by [Our World in 93 Data](https://ourworldindata.org/travel-carbon-footprint). 94 - Plane is counted following 95 [labos1point5](https://labos1point5.org/ges-1point5), including the effect 96 of contrails: 97 - 258 gCO2e/pkm for less than 1000km 98 - 187 gCO2e/pkm between 1001km and 3500km 99 - 152 gCO2e/pkm above 3500km. This value is consistent to the 150 gCO2e/pkm 100 value for long-haul flight given by [Our World in 101 Data](https://ourworldindata.org/travel-carbon-footprint) (also including 102 contrails) 103 - For bus/coach, we count 28 gCO2e/pkm as the coach value given by [Our World in 104 Data](https://ourworldindata.org/travel-carbon-footprint) as there is no 105 value in labos1point5. 106 107 ## Trends relative to 2024 108 109 The number of onsite participants is a little higher, and the number of 110 nonlocal onsite participants is a little lower. The footprints per nonlocal 111 participant are significantly lower: a 22%-27% decrease (depending on whether 112 locals are included or not). Including locals, we get to 202 kgCO2/participant 113 this year, compared to 260 kgCO2/participant last year. Given that the profile 114 of "long trips" is similar to 2024, we ascribe this change to the location being 115 more central. 116 117 Indeed, if the same participants had come to Bordeaux (the 2024 venue), 118 from/to the same places and the same transportation means, then the average 119 footprint per onsite non-local participant would be 316 kgCO2, and per onsite 120 participant 285 kgCO2e, which would then be slightly superior to the 2024 121 edition. 122 123 Of course, organizing the 2025 conference in Bordeaux would have somewhat 124 changed who attends and how they travel -- but maybe this would not be a large 125 change. So our best hypothesis is that essentially the same people came, by 126 the same means, but the total travel to Saarbrücken was smaller. 127 128 Another piece for evidence for this is that the footprint per participant in 129 2023 (in Germany) was 225 kgCO2/participant, so similar to 2025. 130