In 1994, Carlos Alberto Parreira’s pragmatic team won the title in 38°C heat. Next month, when the USA will share its second World Cup with neighbors Mexico and Canada, it should be even worse, with 25% of games played under unhealthy conditions for athletes and fans, shows a study published this Thursday (14).
Offering global warming generated by human activity, especially the burning of fossil fuels.
As in 1994, not even the final escapes. The possibility of a decision being hampered by the heat, however, has only increased in these 32 years: 50% according to an analysis by the World Weather Attribution (WWA), a group of scientists led by Imperial College, London.
Used to comparing extreme weather events with patterns from the pre-industrial era, precisely to verify the responsibility that can be attributed to climate change, the WWA this time used its models in a different way: to check the conditions of the 104 games scheduled for this year and simulate what would have happened with the same table in 1994, which originally had half the matches.
“I remember those games well. My co-authors probably don’t,” said Friederike Otto, professor of Climate Science at Imperial College. In the presentation of the study, the WWA leader joked with the young people in the group, who did not witness matches starting at noon, to attend European TV, and the massacre perpetrated during the American summer.
In Dallas, Germany and South Korea played with temperatures reaching 46°C, an unofficial record for the hottest match in World Cup history. Favorites, the Germans opened 3-0, but were exhausted in the second half, allowing two goals from their opponents.
“More than half of the global warming recorded so far has occurred since 1994, which increases the risk of games in dangerous heat,” said Otto, illustrating how the problem has increased in recent decades.
To carry out the study, the WWA checked the climate that year in the venues, dates and times of the 104 games scheduled for next June and July using a more precise variable, the Wet Bulb Index Globe Thermometer (IBUTG), widely publicized by its acronym in English (WBGT). It is an index that incorporates, in addition to temperature, a measurement of humidity, better reflecting the thermal stress to which the human body is subjected during physical activities.
Thus, 28°C IBUTG is equivalent to approximately 38°C in dry conditions and 30°C under high humidity. For FIFPRO, the global union of professional players, this is the mark that, if reached, should stop a match. FIFA (International Football Federation), as well as other sports federations, works with a much more tolerant limit, of 32°C IBUTG.
“When IBUTG exceeds 26°C, players’ performance can suffer,” said Chris Mullington, a doctor at Imperial College and the NHS, the UK’s public healthcare system. “Above 28°C IBUTG, the risk of serious heat-related illness becomes more worrying, not just for players but also for the hundreds of thousands of fans in stadiums and at fanfests.”
According to WWA analysis, 26 of the 104 games in 2026 have the potential to reach the 26°C IBUTG threshold; another five must exceed 28°C IBUTG, the critical mark in the view of the union and most experts.
Observing this year’s table taken back to 1994 attests to the legacy of climate change on the sport: there would be 21 of the 104 games reaching or exceeding the limit of 26°C IBUTG and 3 at the level of 28°C IBUTG.
The Brazilian team’s third match at the World Cup, against Scotland, in Miami, on June 24, is classified as “almost certain” of reaching 26°C IBUTG. For FIFPRO, once this condition was reached, the game should be suspended to protect the athletes.
The Florida city, with an open stadium, is one of the venues that will host the most “high-risk” games, as the study calls them, including a quarter-final match on July 11. In Dallas and Houston, with air-conditioned arenas, the risk will remain with fans, who will have to arrive and leave the stadiums in hot conditions. “It would be interesting for FIFA and the American authorities to distribute free water, for example,” said Mullington.
For Theodore Keeping, one of the study’s authors, the analysis, subjected to scientific rigor, is conservative. “For example, we calculate the IBUTG temperature in shaded and sheltered conditions. In stadiums without roofs, direct sunlight will be an additional factor.”
As in Pasadena, California, which celebrated the generation of Romário and Bebeto in 1994, the stadium for this year’s final, the MetLife Stadium, in New Jersey, is open.
Last year, at the Club World Cup, also played in the USA, more than half of the games reached or exceeded the 28°C IBUTG level, according to another survey. There were breaks for hydration, but no matches were suspended due to the heat; several were interrupted due to the risk of storms, following American protocol.
FIFA promises to repeat the hydration intervals at the World Cup, but the measure is not seen as sufficient. “According to physiological studies, these stops are not capable of mitigating thermal stress in some circumstances. A longer interval between the first and second periods would be necessary,” said Mullington. On the other hand, a longer event would expose even more fans in the stands.
“From a public health point of view, it would be better to have the World Cup earlier or later in the year,” said Otto, remembering that the Qatar Cup took place at the end of 2022. “Climate is a factor that will increasingly have to be taken into consideration.”
