The Tokyo Games Could End Up Being The Hottest Summer Olympics Ever

Years before the coronavirus pandemic delayed the Tokyo Games, caused an uproar over public safety and left arenas empty, researchers were sounding the alarm over another concern for the world's top athletes: extreme heat.

Tokyo's Olympic and Paralympic Games are expected to be one of — if not the — hottest and most humid Games on record, with daily temperatures expected in the high 80s and low 90s degrees Fahrenheit. With high humidity, that could feel more like 100 degrees — and pose the danger of dehydration, premature fatigue and heat stroke to athletes and Olympic staff.

Before the Games officially kicked off Friday, Russian archer Svetlana Gomboeva fainted during a qualifying round due to heat exhaustion, and in men's tennis, world No. 2 player Daniil Medvedev said Saturday that Tokyo's heat and humidity were "some of the worst" conditions he'd ever played in.

"It's almost like you are in a sauna or something like that," said Makoto Yokohari, a professor in the Department of Urban Planning at the University of Tokyo and an adviser to the Tokyo 2020 Organizing Committee.

What makes Tokyo so hot

Conditions are partly a result of Tokyo's "heat island" phenomenon, in which heat accumulates and gets trapped in the center of the city, resulting in higher temperatures in urban areas.

"You have a lot of emissions like air conditioners and also vehicles and so on," Yokohari said. "Plus, you don't have so much green space in the center of the city."

And at night, when the city cools down, artificial pavements like asphalt and concrete release the heat they trapped during the day.

Heat is only part of the equation, though. Tokyo's high humidity means more water in the atmosphere, which means the sweat on athletes' skin will have a harder time evaporating — the mechanism that cools the body.

The heat might be especially challenging for Paralympians

Katy Griggs, a senior lecturer at Nottingham Trent University who studies sports physiology and human performance, said that could pose a particular challenge for some Paralympians.

"With a spinal cord injury, especially those with a complete break in their spinal cord, they're not able to sweat or control their skin blood flow below the level of their injury," Griggs said. "And evaporation of sweat and losing heat by convection via skin blood flow are the main ways you lose heat in the body surface area."

Griggs co-authored a paper on heat-related issues for Paralympians at the Tokyo Games, but said more research is needed to see the potential effects of heat for Paralympians of different abilities.

"You have to figure out different ways to cool yourself," said Ryan Pinney, an American handcyclist competing in his first Paralympic Games next month.

Pinney suffered a spinal cord injury in 2012, and though he's not using major muscle groups like his thighs while racing, he said they tend to get warm without the ability to perspire. His solution: drench them in water.

Climate change in Japan

Extreme summer heat is no new phenomenon in Tokyo, but experts say the role of human-driven climate change can't be overlooked; Tokyo's Bureau of Environment notes that climate change and the "heat island" effect have contributed to an average mean temperature increase of 3 degrees Celsius (5.4 degrees Fahrenheit) over the past century.

In an email, John Abraham, a professor of thermal sciences at the University of St. Thomas in St. Paul, Minn., noted: "On top of the slow, long-term heating, you get these more intense heat waves, which are probably a bigger concern."

Japan has already felt this. In 2018, more than 1,000 people died in a heat wave. The next year, dozens died and thousands were hospitalized after an exceedingly hot July. In Paris, host of the 2024 Summer Olympics, a heat wave last June and July broke the city's all-time temperature high (108 degrees Fahrenheit). More than 1,400 people died across the country.

For years, Tokyo has been planning for a hot Olympics. After an effort to line the Tokyo marathon course with tiny, heat-reflecting beads, organizers made the decision in 2019 to move it more than 500 miles north, to the city of Sapporo. Organizers are also providing salt candies and tablets for media members and volunteers, and misting stations are set up around the city. National Olympic committees have brought slushy machines and cooling vests, and Team USA has battery-powered cooling jackets that self-regulate temperatures like a personal HVAC system.

It all makes Yokohari wonder why the Games are happening at all. He called the decision to host the Games — despite intense summer heat and, more recently, growing coronavirus cases — "just ridiculous."

And as cities continue to warm and heat waves increase in frequency and intensity, Yokohari isn't optimistic that, in the long term, future Olympic Games could safely take place in the summer.

"We say 'Summer Olympics,'" Yokohari said, "but [the International Olympic Committee] should adjust it to maybe fall or early spring. And that will be the only way that I think most of the cities in the world will be able to host the Olympic Games."