Unstable summer weather threatens to turn World Cup into heat test

The World Cup will begin this Thursday (11) under the typical threats of the North American summer: extreme heat, suffocating humidity and storms capable of delaying matches with little notice.

Seasonal forecasts call for above-normal temperatures across much of the United States, while moisture flowing from the northern Gulf of Mexico could fuel storms and severe weather during the first few weeks of the tournament.

While conditions for individual matches cannot be predicted that far in advance, sports scientists say there are clear weather-related risks to a summer World Cup that will span Canada, Mexico and the United States.

The fundamental measurement is not just air temperature, but rather wet-bulb and globe temperatures, which incorporate heat, humidity, sunlight and wind to estimate thermal stress on the body.

The World Weather Attribution has warned that approximately a quarter of matches may be played in conditions that exceed recommended safety limits.

Internal heat challenge
Chris Minson, professor of physiology and co-director of the Exercise and Environmental Physiology Laboratories at the University of Oregon, said elite players generate enormous internal heat even before taking weather conditions into account.

"Seventy-five percent of all the energy we use during exercise is converted into heat," Minson told Reuters. "Only about 25% is used to perform the exercise itself."

In hot, sunny or humid conditions, the body's natural cooling system begins to experience difficulties. Humidity is a particular concern, as sweat only cools the body when it evaporates.

"One of the hardest things for us is when the humidity is really high," Minson said. Cities hosting the World Cup in locations with high humidity include Houston, Miami, Dallas and Monterrey.

Weather's impact on performance
According to new research from Climate Central, climate change has increased the likelihood of temperatures high enough to affect players' performance in 97 of the tournament's 104 matches.

The biggest predicted increase is for the group stage match between Uruguay and Spain in Guadalajara on June 26, where researchers estimated a 70% probability that heat will harm performance - 37 percentage points more than it would be without climate change.

Ryan Calsbeek, a professor of biological sciences at Dartmouth College who studies how body type affects athletic performance in different climates, said heat and humidity can influence not only players' well-being but also the pace and style of matches.

"Higher temperatures and humidity will likely slow down games," he said. "When athletes must perform for an extended period, they simply will not be able to balance the explosive power of their fast-twitch efforts with the long-duration aerobic effort of a 90-plus minute game in heat and humidity."

Nearly half of all matches face at least a 50% chance of temperatures above 28 degrees Celsius (82.4 degrees Fahrenheit) - a threshold associated with decreased speed, distance covered and recovery time.

Calsbeek said Mexico City's altitude - about 2,240 meters (7,350 feet) above sea level - could also be a significant factor, particularly for those arriving from lower altitudes without time to acclimatize. The city will host five matches.

FIFA stated that all World Cup matches will include a three-minute hydration break in each half, and that decisions about the calendar took into account factors such as average temperature, travel, rest days, medical planning and refrigeration infrastructure.

Safety protocols questioned
Several venues have retractable roofs or climate control systems, and tournament regulations allow matches to be postponed, suspended, rescheduled or moved for health, safety or security reasons, including adverse weather conditions.

Minson said FIFA should require interventions when the wet bulb temperature reaches 26°C and should consider postponing matches when the temperature is between 28°C and 30°C.

Minson also requested six-minute cool-down breaks, shaded cool-down areas, emergency ice baths, and longer breaks when conditions warranted.

"If you have a player who appears to be delirious, who isn't thinking straight or who faints on the field, you need to calm him down immediately," he said.

For FIFA, the tournament is a logistical showcase. For players, coaches and scientists, it could also be a test of how football adapts to a warmer future.

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Source: CNN