Researchers warn that footballers stand a “very high risk of experiencing extreme heat stress” at 10 of the 16 venues hosting the next World Cup, urging sports administrators to reassess event timing.
The study found that hot weather and intensive exercise could force footballers to withstand temperatures above 49.5C (121.1F) in three North American countries in 2026. Stadiums in Arlington, Houston, and Monterrey, Mexico, are most likely to cause “unacceptable thermal stress” on them.
As temperatures rise, co-author Marek Konefal of Wroclaw University of Health and Sport Sciences in Poland predicted World Cups would be contested in extreme heat. “It’s worth rethinking the sports calendar.”
Fifa recommends cooling pauses if the “wet bulb” temperature surpasses 32C. Scientists worry that the statistic understates athletes’ stress on the pitch by just considering environmental heat and humidity.
“During intense physical activity, the player’s muscles produce huge amounts of heat,” said Polish Academy of Sciences climate scientist Katarzyna Lindner-Cendrowska, the study’s primary author. “This will increase the athlete’s overall heat load.”
The researchers simulated temperatures that account for players’ speed, activity, and apparel to overcome this. They only partially included exertion in the heat index.
Julien Périard, deputy director of the University of Canberra Research Institute for Sport and Exercise, who was not involved in the study, said the heat index’s highest “work rate” is half that of professional football players. “The study’s approach is promising, but the results may underestimate the risk of extreme heat stress.”
All but one stadium had the most stress between 2pm and 5pm, according to scientists. They discovered that mid-to-late afternoon temperatures above 50C in Arlington and Houston put a “heavy burden on the body” that could cause heat exhaustion and heatstroke.
Hotter, longer, and more frequent heatwaves are due to fossil fuel emissions. Saudi Arabia, the world’s largest oil producer, may host the 2034 Fifa Men’s World Cup. Saudi Aramco sponsors the 2026 tournament.
Last year, the Climate Social Science Network showed Saudi Arabia has disproportionately hampered climate negotiations.
“The fossil fuel giant has a 30-year history of obstruction and delay, protecting its national oil and gas sector and ensuring UN climate talks achieve as little as possible, as slowly as possible,” the authors said.
Saudi Aramco and Fifa declined comment. In April, Fifa president Gianni Infantino said he was “delighted” to welcome Aramco to its worldwide partners.
Scientists advocate reducing fossil fuel pollution and adjusting to a hotter globe to protect people from heat. The 2022 men’s World Cup in Qatar employed air-conditioning outdoors to keep players cool, but the study did not model its impacts.
Périard, who has published Fifa-funded research on heat stress, said the new study could help tournament organizers optimize match scheduling but that Fifa needed to “take action” on their current policy of using the wet bulb index to decide cooling and hydration breaks.
He proposed extending half-time intervals and postponing matches as part of a football-specific heat stress policy that considered sweat.
ISGlobal climate and health researcher Thessa Beck, who was not involved in the study, said fans must be protected. Fans may not be as active as players, but many are older persons, children, or people with pre-existing ailments.
