More than 100 professional female footballers signed a letter condemning Fifa's 2024 four-year partnership with Aramco, citing environmental impacts ahead of the 2026 World Cup in Canada, Mexico and the United States. Aramco, a state-owned Saudi energy company, is the largest corporate greenhouse gas emitter and is responsible for more than 4% of all emissions since 1965.

"Aramco is one of the biggest polluters of the planet we all call home. In taking Aramco's sponsorship, Fifa is choosing money over women's safety and the safety of the planet," Canada national team captain Jessie Fleming said.

Researchers project the 2026 tournament will generate around 9 million tons of carbon dioxide equivalent, with air travel comprising approximately 7.7 million tons of the carbon budget — more than four times the average for tournaments held between 2010 and 2022. The worst-case upper estimate for air transport emissions is about 13.7 million tons of CO2.

Fifa increased the number of participating teams to 48 for the 2026 edition, up from 32 at the 2022 tournament in Qatar. The expanded field, spread across three host countries, will require long-haul travel between matches. The Bosnia and Herzegovina national football team, with a training camp in Salt Lake City, will travel more than 5,000 kilometers from Toronto to Los Angeles and then to Seattle. The Algeria national football team will fly about 4,800 kilometers between Kansas City and San Francisco and back, while Czechia will travel more than 4,500 kilometers from Guadalajara to Atlanta to Mexico City.

The National Weather Service is warning that every region of the U.S. will experience temperatures exceeding historical averages during the two months in which the tournament will take place. An academic study found that 14 out of 16 host cities are likely to experience average wet bulb globe temperatures exceeding 28°C in June and July, a threshold at which Fifpro has argued matches merit possible suspension. A Guardian analysis found that 26 matches will be played when the wet bulb globe temperature is at or above 26°C. Three host cities — Houston, Dallas and Atlanta — have air-conditioned stadiums.

"What is perhaps most absurd to me is the lack of commonsense preparations by event organizers to keep people safe in extreme weather conditions. Hot and humid weather is predictable in North American summers," University of Toronto researcher Dr Madeleine Orr said.