Fig. 2.

Percentage increase of travel footprint with respect to the city corresponding to the minimum footprint (Detroit), for cities hosting a large international airport in the United States. The X-IFU footprint calculator was run with the average of the ADEME, myclimate, and DEFRA estimates, assuming train journeys for great circle distances less than 700 km. With these assumptions, for the AGU 2019 Fall meeting, the city minimizing the overall footprint would have been Detroit (while the meeting was held in San Francisco). The total footprint associated with San Francisco was ∼ 5000 tons of CO₂eq higher (11%). The four upcoming meetings are San Francisco (2020), New Orleans (2021), Chicago (2022) and San Francisco again in 2023. They are highlighted by green and red bars. Assuming the same audience as the 2019 Fall meeting, the travel footprint associated with New Orleans for the 2021 meeting would be 13% higher than a similar meeting held in Detroit