Between July 24 and Aug. 9 of this year, the temperature in Tokyo reached an average high of 92 degrees Fahrenheit, 6 degrees above the 30-year average. The average humidity reached higher than 80 percent, and the average heat index approached 120 degrees Fahrenheit. More than 20,000 people across Japan were hospitalized because of the heat, and nearly 70 people died.

The Tokyo Olympics are taking place from July 24 to Aug. 9, 2020. Do competitive sports and about 500,000 tourists under similar conditions sound like a good idea?

“Fundamentally, we should not be having the Tokyo Olympics in midsummer,” said Makoto Yokohari, a professor of environmental studies at the University of Tokyo. “Considering climate change, now it should be held in November.”

The 1964 Tokyo Olympics, the first games ever held in Asia, were also the first to be telecast live around the world, uniting the globe around sports. They were also held in a cold and rainy October. As reported Thursday by the New York Times, the biggest reason the Olympics are being held in the summer this year is the outsize influence of American television and NBC on the scheduling.

That means that next summer, the world could unite instead around the shock and horror of the first Olympics marred by climate-related deaths. As countries lag far behind their Paris agreement commitments to mitigating the crisis—and after a recent round of U.N. climate negotiations that made very little progress—the 2020 Tokyo Olympics could be the first climate disaster broadcast and streamed live for all to see.

As global temperatures have risen 1.4 degrees Fahrenheit above the preindustrial average, Japan and its aging population have suffered brutal, long-lasting heat waves that would have been scientifically impossible if not for human-induced global warming. Climate change has already caused increased deaths from heat stroke and is expected to degrade the country’s rice supply, intensify Japan’s frequent natural disasters, and threaten key ecosystems—all by 2100.

According to data that the Tokyo Metropolitan Government provided to me, the heat island effect—a phenomenon where urban areas build up additional heat—has caused the average temperature in Tokyo to rise by more than 5 degrees Fahrenheit in the past 100 years. Yokohari expects that during the games, there could be days where temperatures reach 100 degrees Fahrenheit with more than 80 percent humidity. “That means that no one should be in the open air unless in an emergency situation,” he said.

But hundreds of thousands of tourists will swarm Tokyo’s streets next summer, turning the city’s famously crowded—but functional—intersections and subways into a boiling tourist bath. Companies are already telling Tokyo locals to just stay away from it all and work from home for their own safety.

Multiple trial events this past summer were canceled because of extreme heat. The athletes tend to have professional trainers who keep careful track of their bodies as well as the weather conditions, and most should know how to adjust their performances to the heat—though it’s still possible some may overextend themselves in the moment. Spectators face the bigger life-or-death risk. It takes time to adapt to a new environment, especially humidity and heat. Tokyo provided me with data showing that the city’s heat stroke incidents increased exponentially with temperature, starting to spike right around the 91- and 92-degree mark.

“Athletes will be well trained and can just stop playing if they feel uncomfortable,” Yokohari said, “but spectators may not have access to the same treatment.”

Anyone who lives in Tokyo knows and complains about the sweltering hot, squelching humid summers (the latest survival fad: strap-on portable electric fans). This June, the Tokyo Olympic committee released a comprehensive 38-page plan with countermeasures for extreme heat.

The Olympics will provide large misting fans and colorful rows of flowers to create cool microclimates. There will be air-conditioned rest areas and medical rooms for those who inevitably get heat-sick. Ice buckets and lots of electrolytes will bolster the athletes; sunglasses and intensive heat training will protect staff. The city government is installing extensive shade, greenery, and misting towers, and it plans to distribute fans and cold packs. It’s an impressive effort by the Olympic committee and the entire city to make conditions habitable.

Around the world, cities are scrambling to adapt to extreme heat. If climate inaction continues, the average temperature of cities could rise 9 degrees Fahrenheit by the century’s end, transforming D.C.’s climate into something like Dallas’. Even if the world hits the Paris agreement target of limiting global warming to 2 degrees Celsius, cities will face complete paradigm shifts in a short period of time.

Susannah Drake, an architect at DLANDstudio focusing on environmental design, said that city climate adaptation is absolutely a matter of safety. “In many cities, there’s nowhere to get cool,” she said. “A lot of vulnerable populations don’t have access to air conditioning, but air conditioning exacerbates the problem, because air conditioners work by spitting hot air out into the environment.”

Still, there’s a lot that any city can do to adapt to the heat without changing the underlying structure of the city. “Lighter color surfaces are more reflective, so they don’t absorb heat. In places where you can’t have green roofs, have lighter-color ones,” Drake said. “Plant as much greenery as you can. You can also get a lot of natural cooling by orienting your buildings correctly to allow for air circulation.”

Tokyo lacks these climate-sensitive features. Rebuilt after World War II, decades before the advent of climate consciousness, Tokyo doesn’t have nearly as many parks as other cities. Hot, dark pavement runs rampant. Just 7.5 percent of the city is public green space, compared with 47 percent of Singapore, 46 percent of Sydney, and 40 percent of Hong Kong.

Yokohari said that the city needs widespread changes to adapt to the climate crisis, starting with building more green areas and finding a way to maximize the wind corridor to the Pacific. “In order to avoid the heat island effect, we really should make Tokyo smaller, into a chain of connected miniature cities,” he said. “If we want to fully address climate change, these sorts of measures should be considered.”

While Tokyo is taking action against climate change, including a carbon cap-and-trade policy and an environmental building code for new construction, the date of the Olympics isn’t changing, and the city sure isn’t getting any smaller. The Olympic committee has put preparations in place, but there’s no countermeasure for human ignorance. Given the rate of heat stroke in a warming Japan, it’s inevitable that Tokyo locals and Olympic spectators, staff, and athletes will fall ill next summer. But the scope of the human cost remains unclear. We could see just a hundred or so visitors hospitalized. But the worst-case scenario would feature dozens of deaths.

Peter Kalmus, a climate scientist and writer, says it’s hard to tell whether or not climate-related disasters in the past few years—from the California wildfires to Hurricane Dorian—have helped accelerate public discourse or action on the crisis.

But if people die in Tokyo next summer, it will be a different experience. The Olympics are an event that fans watch with the expectation of being entertained, even inspired. If the games suddenly turn tragic, the world won’t be tuning in to willingly witness some disaster that climate change either caused or exacerbated. For millions of spectators, it will be an entertainment and a tradition ruined by a climate-caused tragedy.

“We need to break out of the norm that we’ve lived in for as long as we’ve had fossil fuels,” Kalmus said. “We need to be able to imagine big changes.” He recommends moving away from fossil fuel–intensive activities and entities like carbon-fueled airplane flight, natural gas power plants, and large oil corporations. “Anyone can participate in any number of ways, up to and including nonviolent, direct action. We should consider this a rational response.”

There’s a lot hinging on Tokyo 2020. The 2024 Olympics will be held in Paris, which experienced its highest temperature ever recorded this summer at 108.7 degrees Fahrenheit. The 2022 FIFA World Cup will be held in Qatar in winter, not summer. (In Qatari summers, Paris’ hottest day ever is just another day.) Just earlier this week at the track and field biennial world championships in Qatar, while air-conditioned stadiums mitigated conditions, female runners were carried away on stretchers after running the marathon outdoors.

“If Tokyo fails to handle the heat, cities could start to say, ‘We don’t want to have the Olympics,’ ” Yokohari said. “Tokyo should realize that it sits on a critical point of the future of the Olympics. Next year Tokyo will show whether the Olympics can be done in a very hot climate, or give the simple answer that it’s impossible.”