In eight months' time the 2026 World Cup will make history as the biggest single sporting event. But not everyone is celebrating. Amid the excitement, concerns are growing about the environmental cost of the vastly expanded tournament, drawing criticism from academics, players and fan groups. BBC Sport looks at some of the key issues.

Dr Madeleine Orr is a leading sport and climate expert who believes the 2026 World Cup "sends a dangerous message about the intentions of Fifa and other events to just get bigger and bigger". Next year's tournament in the United States, Mexico and Canada will be the first to be held across an entire continent, feature 48 teams and have 104 matches - 40 more than before. Fifa is considering expanding the tournament to 64 teams for the 2030 edition.

"It's completely misaligned with the promises [Fifa] have made publicly to reduce emissions," says Dr Orr, assistant professor of sport ecology at the University of Toronto. "At this point, it's damage control."

In their original bid for the 2026 World Cup, the three prospective host nations hoped the event would "establish new standards for environmental sustainability" and deliver "measurable environmental benefits". But Dr Orr is sceptical. "If the new standard is the most carbon-intensive event ever, then yeah," she says with sarcasm. "No, I don't think that's possible," she adds.

Recent research from the Scientists for Global Responsibility (SGR) calculated the expanded tournament will generate more than nine million tonnes of carbon dioxide equivalent, making it the most "climate damaging" edition in the tournament's history. It could also be one of the hottest.

In total, 14 of the 16 host cities for the World Cup are expected to be vulnerable to extreme heat during the tournament. Dr Orr believes that from 12pm to 4pm, many of these venues would be "virtually unplayable". Fifa has suggested adjusting kick-off times and relying on a handful of stadiums with roofs - their plans will become clearer after December's World Cup draw - but critics argue the risk extends beyond the pitch.

"I'm not worried about the athletes," Dr Orr explained. "I worry about 45,000 to 85,000 fans, the 10,000 staff and media personnel who are on site for prolonged periods. It's going to be a challenge to figure out how to keep people safe. It is a conversation that's being had, but as of today there is no firm plan on that."

Fifa declined to comment when approached by BBC Sport, and also declined to answer detailed questions about its sustainability strategy and contingency plans, external in the event extreme weather forces a change to the schedule.

However, speaking this month at the European Football Clubs (EFC) general assembly in Rome, Fifa president Gianni Infantino acknowledged that extreme heat in future summers might force a rethink of football's global calendar.

"We are discussing all the time, and I think it's not just about one World Cup - I think it's a general reflection," he said. "Even to play in some European countries in July, it's very, very hot. So maybe we have to think. There are ways we can optimise the calendar. But we are discussing it, and we will see when we come to some conclusion. We just have to have an open mind."

The struggles of playing in high temperatures in the US have been talked about for some time. In 2017, England forward Rachel Daly was treated for heat exhaustion in hospital after collapsing during a match in Houston, while playing in the National Women's Soccer League (NWSL). The heat was a constant theme of this summer's Club World Cup. Record-breaking temperatures and violent storms wreaked havoc across the tournament. Lightning meant six games were delayed from 40 minutes to two hours.

Chelsea were one of the teams to struggle with the extreme heat. At their semi-final against Fluminense in New Jersey the temperature rose to more than 35C by kick-off, with midfielder Enzo Fernandez saying the conditions made him "dizzy" and were "very dangerous".

USA 1994, remembered for the 41C the Republic of Ireland played in against Mexico in Orlando, was the hottest World Cup so far. BBC's senior weather forecaster Simon King said recently next year's tournament could surpass that.

"In June 2023, an extreme heatwave was seen in Texas, Florida and Mexico for weeks. In Monterrey, Mexico the heat index was close to 50C and in Miami it was as high as 44C. It is impossible to say a year ahead whether host cities like those will experience heatwave conditions - climate change has loaded the dice to an increasing chance of this happening. And if it does, it could feasibly be the hottest World Cup on record."

Five US cities (Boston, Dallas, Los Angeles, New York/New Jersey and San Francisco) which hosted games in 1994 are also hosting in 2026. Data provided by Climate Central to BBC Sport showed that all those US cities (except San Francisco) experienced significantly more days above 32C, external in June 2025 than they did in 1994.

David Wheeler, former Wycombe Wanderers midfielder and one of football's most vocal environmental advocates, sees climate change increasingly affecting the game, saying it is "becoming a lot more obvious to players and more of a topic of conversation".

Wheeler, who is the Professional Footballers' Association (PFA) Sustainability Champion, believes the sport has a responsibility to do more. "Unfortunately I don't think the major governing bodies and organisations are really taking that responsibility seriously at the moment," he says. "These organisations don't deserve to profit from sport if they're not going to use their power for the betterment of sport."

Wheeler also wants footballers to use their platform more to speak out on environmental issues. "It could have a huge impact," he said. "But it's also important that clubs and fans' groups also insulate the players because there's going to be that inevitable backlash that they're a hypocrite. The majority of us are hypocrites to some degree. We're not perfect and that's OK, just as long as we're trying to do as much as we can."

One player who does not shy away from using his platform to champion environmental issues is Real Betis defender Hector Bellerin. Speaking after he was named Global Champion at the recent BBC Green Sport Awards, he said it was not easy to promote sustainability in a sport increasingly defined by global expansion.

"It's hard," he said, referencing the 2026 World Cup. "I don't make the decisions and I'm very aware of how the industry works. But I'm not going to stop doing what I love because of decisions made at the top. We players often feel like we're treated like numbers or marketable goods. There's more games, more travel, more difficult conditions. And we're just told to hydrate," the former Arsenal player added. "Unless footballers around the world unite - whether that means stopping or taking bold decisions - the wheel's just going to keep turning," he said.