The 2026 World Cup we are all half looking forward to and half dreading may become the first major event where rising temperatures degrade the quality of the game, so much that the future of football will never look the same.

The beautiful game has survived two world wars, countless corruption scandals and, of course, the introduction of VAR. Whether it can survive thermodynamics is another matter. When the 2026 World Cup kicks off across the United States, Canada and Mexico in June, it will do so against a climatic backdrop that should concern anyone who cares about the sport or the athletes who play it.

The tournament will be the largest in history, expanded to 48 teams playing 104 matches across 16 venues over approximately five weeks. Many of those venues, Dallas, Houston, Miami, Monterrey, Guadalajara and Atlanta among them, sit in regions where summer temperatures routinely exceed 35°C, often accompanied by punishing humidity. This alone presents a formidable physiological challenge for players. But 2026 may bring something worse. Climate scientists increasingly expect a significant El Niño event to overlap with the tournament window, which could layer additional warming on top of what is already an accelerating baseline trend in global temperatures.^1,2 The years 2023 and 2024 both shattered global heat records, driven in part by the interaction between anthropogenic climate change and El Niño's cyclical warming of Pacific surface waters.^3,4 Should a strong El Niño materialise in 2026, the tournament could face conditions unprecedented in World Cup history.

How will this affect the players? The human body dissipates excess heat, such as that generated by exercise, through a remarkably elegant system: blood is redirected to the skin's surface to carry dangerous heat away from the organs, while sweat evaporates, releasing thermal energy into the air.  During a tournament match, where an average midfielder might run 9 to 13 kilometres, this system comes under huge strain.^5,6 Working muscles demand blood flow for oxygen delivery at precisely the moment the cardiovascular system needs to shunt blood to the skin for cooling. When ambient temperature and humidity rise, the heat-dissipating power of evaporating sweat is increasingly impaired: this competition becomes a zero-sum game that the body eventually loses.⁷

During the 2014 World Cup in Brazil, the number of sprints and sprint distance dropped by approximately 10%, and the number of red cards increased by around 50%, in matches played in the hottest and most humid conditions compared to those in temperate venues.⁸  Players were forced to change their tactics during the most heat-stressful conditions, and the tournament was the first to introduce mandatory cooling breaks.^8,9

Not all bodies suffer equally. Football squads contain a range of phenotypes from lean, wiry midfielders to heavily muscled defenders and goalkeepers.¹⁰ Research shows that athletes with higher body mass and greater body fat percentage are more vulnerable to heat stress, owing to their lower surface area-to-mass ratio and the insulating properties of adipose tissue.^11,12 An 85 kg defender generates substantially more metabolic heat than a 70 kg winger, yet has proportionally less skin surface through which to shed it. The footballing implications are obvious: the physical profiles that confer advantages in strength, aerial duels and physical presence become liabilities when the temperature climbs.

Heat acclimatisation, the process by which the body adapts to thermal stress over 10–14 days of progressive exposure, remains the single most effective countermeasure available.¹³ Acclimatised athletes sweat earlier and more profusely, maintain lower core temperatures and show improved cardiovascular stability.¹³ But the compressed international calendar and the demands of domestic league seasons mean that many players will arrive in North America with minimal acclimatisation. Teams from northern European countries like Germany – historically among the tournament’s strongest – and our own England and Scotland, which sadly are not, may find themselves at a particular physiological disadvantage against opponents from warmer climates whose bodies are already adapted to the heat.

Perhaps the most insidious effect of heat, however, is not visible to spectators or cameras. A growing body of neuroscience research demonstrates that elevated core temperature impairs cognitive function well before it produces obvious physical symptoms. Working memory, reaction time, decision-making speed and executive function all deteriorate as core temperature rises above 38.5°C, and impulsivity may increase.^14,15 In a sport where the difference between a perfectly weighted through ball and a misdirected pass is measured in milliseconds of judgement, this cognitive erosion may matter more than any reduction in running distance.

Tim Noakes’s influential Central Governor theory proposes that the brain pre-emptively throttles physical output to protect the organism from thermal catastrophe.¹⁶ If correct, the sluggish, error-strewn passages of play that characterise hot-weather football are not merely the result of tired legs; they are the brain’s emergency brake being applied, whether the player consents or not.

The consequences of getting this wrong extend far beyond sporting aesthetics. Exertional heat stroke, a medical emergency in which core temperature exceeds 40°C and the thermoregulatory system collapses, carries a significant risk of organ damage, neurological injury and death if not treated aggressively within minutes.¹⁷ While fatalities are rare at the elite level due to extensive medical infrastructure, the 2019 World Athletics Championships in Doha demonstrated how conditions can overwhelm even well-prepared athletes: 41% of women’s marathon starters failed to finish, average speed was reduced compared to previous years and multiple runners required emergency medical treatment.¹⁸ Football’s intermittent nature offers some protection compared to continuous endurance events, but a 90-minute match with extra time in 35°C heat and 80% humidity in Houston is not a trivial physiological challenge.

Moreover, emerging evidence suggests that a player who suffers a single episode of severe heat illness may find their future ability to tolerate heat reduced, a potentially career-altering consequence in an era of increasingly hot tournaments.^17,19

Tournament organisers have tools at their disposal. Cooling breaks, flexible kick-off times and venue-specific scheduling that accounts for local climate data are all proven interventions. The technology deployed in Qatar’s air-conditioned stadiums in 2022 demonstrated what is possible when resources are practically unlimited, though replicating that approach across 16 North American venues is neither practical nor environmentally defensible. Are current measures adequate for this World Cup? Time will tell, but protecting the health of athletes must be a priority.

The deeper question is whether football's governing bodies and host countries are prepared to accept that climate change is not a temporary inconvenience but a permanent constraint on when, where and how the sport can be played, irrespective of maximal viewership and other priorities. The 2026 World Cup may not be ruined by heat (unless FIFA makes another U-turn on water bottles).²⁰ But it may force an uncomfortable reckoning: the climate is changing, and football may have to change with it.

The question is whether the game that emerges will still be recognisably the same one. The beautiful game, like everything else on a warming planet, will have to learn to live within new limits, or watch its quality slowly wither under a merciless sun.

By Stephanie Maury

References

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