The article examines the carbon footprint of the 2026 FIFA World Cup after FIFA did not publish an updated estimate of the tournament's greenhouse gas emissions.Although the original joint bid by the United States, Canada and Mexico projected emissions of 3.7 million tonnes of CO₂ equivalent across 80 matches, the final tournament expanded to 104 matches and attracted nearly seven million spectators.To estimate the environmental impact, the authors developed a computer model using match schedules, team travel and attendance data.Their analysis estimated total emissions of around 3.

2 million tonnes of CO₂ equivalent, which is lower than the original bid estimate and substantially below pre-tournament forecasts from other organisations that projected between 7.8 and 9 million tonnes.

The authors argue that the lower estimate is largely explained by the use of existing stadiums, reducing construction-related emissions, and by a tournament schedule that limited some travel requirements.

They also conclude that travel by spectators accounted for almost 90% of the tournament's emissions, making assumptions about international attendance the biggest source of uncertainty.

Depending on how aviation's broader climate impacts are calculated and how many supporters travelled from overseas, the total emissions could vary significantly.

The authors note that official border agency data from the United States, Canada and Mexico, expected from August, will provide stronger evidence about spectator travel patterns and allow their modelling to be tested against real-world data.Until then, they argue that estimates remain provisional rather than definitive.