Athletes could be killed competing at this summer’s Olympics due to extreme heat caused by global warming, an alarming new report has warned.

Competitors at Paris 2024 will potentially be at risk of heat stroke “that may have long-term, multi-organ consequences and may even be fatal”, according to the report produced by the British Association for Sustainable Sport (Basis) and FrontRunners.

Their second ‘Rings of Fire’ report into how heat could affect a summer Olympics is packed with warnings from athletes themselves that they or others taking part are in danger of being killed.

Climate change is also branded “an existential threat to sport” that will render “at least a dozen” countries uninhabitable by 2060 in a foreword to the report by Lord Coe, the president of World Athletics and the architect of London 2012.

The report, published just over five weeks before this summer’s Games, is the second this month to forecast catastrophic consequences for sport if global warming continues unchecked.

The first, commissioned by World Rugby, warned that Gloucester’s Kingsholm Stadium was among a number of major venues worldwide at risk of “marine submersion” if average temperatures worldwide rose by two degrees centigrade.

The Rings of Fire report follows one that came out before the Tokyo Games which also raised concerns about the impact of heat there. That report proved to be prophetic.

The latest version of the report lays bare the impact of an Olympics that was dubbed “the hottest in history” after the temperature and humidity in Tokyo exceeded 34C and almost 70 per cent, respectively.

It states: “Competitors vomited and fainted at finish lines, wheelchairs were deployed to carry athletes away from sun-scorched arenas and the fear of dying on court was even raised mid-match by the Tokyo Games’ No 2-seeded tennis player Daniil Medvedev.”

Warning it would be “a mistake” to dismiss the threat of extreme heat at Paris 2024, which is being staged mainly in northern France, the report adds: “The fact that the Olympics will take place during high summer means that the threat of a devastating hot spell is a very real one.”

‘Not in an athlete’s DNA to stop’

The dire forecast is endorsed by current, former and prospective Olympians, including medal-winners from previous Games and world champions across various sports.

Jamie Farndale, the Scotland rugby sevens star hoping to help Great Britain qualify for this summer’s Games, is quoted saying: “What we do is push ourselves to our limits, and if we have to do so in conditions that are unsafe I don’t think the athlete would hold back. It is not in an athlete’s DNA to stop and if the conditions are too dangerous I do think there is a risk of fatalities.”

Marathon swimmer Amber Keegan alluded to the death in 2010 of American Fran Crippen at an open-water race in the United Arab Emirates, which forced the introduction of upper temperature limits in the sport.

“We do all get in that water knowing that people have died from the heat,” Keegan said. “It’s not something to be trifled with.”

Two-time Olympic sailing champion Hannah Mills added: “We’ve had athletes whose core body temperatures have gotten up to 39.5C during training in extreme heat, which poses really significant health risks. It’s scary.”

Tennis player Marcus Daniell, who won a bronze medal for New Zealand in the men’s doubles at Tokyo 2020, told the report’s authors how he had feared for the worst during the competition.

“I felt like the heat was bordering on true risk – the type of risk that could potentially be fatal,” he said. “One of the best tennis players in the world [Medvedev] said he thought someone might die in Tokyo, and I don’t feel like that was much of an exaggeration.

“We sometimes have to play in conditions where an egg can literally be fried on the court. This is not fun or healthy. Heatstroke is relatively common in tennis.”

He added: “I don’t believe there should have to be a series of heat-related deaths for us to put reasonable limitations in place.”

Need for ‘radical reassessment’ of fossil-fuel sponsors

The report contains five recommendations for sporting authorities: smart scheduling to avoid heat extremes; keeping athletes and fans safe with better rehydration and cooling plans; empowering athletes to speak out on climate change; boosting collaboration between sporting bodies and athletes on climate awareness campaigns; and reassessing fossil-fuel sponsorship in sport.

On the latter, the report highlighting partnerships including that of TeamGB with British Gas, adding: “If sport is going to take its sustainability and environmental commitments seriously to minimise the climate-change impacts experienced by athletes and spectators during sporting events, it will need to conduct a radical reassessment of its relationship with fossil-fuel companies as an essential component.”

Coe, meanwhile, cited the threat posed by rising sea levels as one consequence of global warming, writing in his foreword: “At least a dozen, probably more, of our member federation countries will no longer be inhabitable by 2060.

“Climate change should increasingly be viewed as an existential threat to sport.

“We are in a race against time. And this is one race that we simply cannot afford to lose.”

Athletes face ‘particular kind of risk’

Basis is a sustainability hub for the UK sports industry, members of which include Arsenal, Chelsea, Celtic, the Rugby Football Union, the England & Wales Cricket Board, Marylebone Cricket Club, the All England Club and the Jockey Club.

FrontRunners was founded by former Australia rugby star David Pocock and his wife, Emma, who are leading campaigners for action on global warming.

Pocock, who serves as a senator in the Australian government, told Telegraph Sport: “This new report shows the serious impacts of climate-fuelled extreme weather on the Olympics. We know the climate is changing and increasing the frequency and intensity of extreme heat events and other climate disasters. Of course, this impacts all parts of our society – all of the people and places we love, and the highest levels of sport are no different.

“Reading the testimony of so many athletes who have already experienced the impacts of extreme heat is alarming. So, too, is the likelihood of these impacts worsening as the world fails to take the necessary action to keep warming to well below two degrees. In the field of contest, where athletes are taught to push themselves beyond physical limits, this has a particular kind of risk that must be managed by those who govern the games we love.

“As the Olympics approach, I’d urge the organisers to take every step necessary to protect competitors, officials, and spectators. Importantly, I’d urge all of us to do what we can to end the expansion of the fossil-fuel industry and rapidly transition to renewable energy to give us the best chance of protecting the people, places, and games we love.”