Today’s newsletter looks at how people are pushing their bodies to the limit to increase knowledge about the impacts of extreme heat and save lives. You can read and share the full story on Bloomberg.com. For unlimited access to climate and energy news, please subscribe. 

Meet the humans inside a 104F heat lab

By Zahra Hirji 

When I spoke with University of Ottawa physiologist Glen Kenny over the phone in early June, he had just started a three-day heat trial inside a special campus lab chamber set to 40C (104F). Kenny was offering up his body to science.

The goal was to see how his 61-year-old frame held up in the same brutal indoor temperatures observed during a 2021 heat wave that killed hundreds of Canadians.

“I have three different sensors in my body right now, and they’re all reading differently,” he said. “My rectal temperature is 36.8C, my esophageal is 37C, and my pill”—a sensor in the gut after he’d swallowed it—“is reading 37.3C.”

Beyond temperature data, Kenny’s team was tracking his heart rate, his body’s ability to regulate blood pressure, and frequently drawing his blood. The team was also monitoring their boss’ mood and reaction time. “I can absolutely tell you that by day three, I’m not going to be the same person,” Kenny said.

He was right. Though Kenny felt fine that first day, by the second, his temperature briefly spiked to nearly 104C, a dangerous level. “I can’t get comfortable,” he said. “Concentration is definitely off.” By the third day, he’d lost roughly 10 pounds (4.5 kg).

Glen Kenny beside the Snellen air calorimeter at the Human and Environmental Physiology Research Unit of the University of Ottawa. Photographer: Justin Tang/Bloomberg

Over decades studying the effects of extreme heat on human health, Kenny has repeatedly put his body on the line to understand the risks scorching temperatures pose to a growing number of people as climate change makes the world hotter. He is among a global group of scientists simulating heat waves in sealed environmental chambers to improve our understanding of how high temperatures damage the human body and how to keep people safe. That work is helping governments rewrite public health standards and companies from Adidas AG to United Airlines Holdings Inc. improve products and worker protections in a bid to minimize the mounting cost in lives and monetary losses.

I’d initially planned to visit Kenny’s lab right after the trial, but he got sick. When I finally made it in July, the first room he showed me contained the world’s only Snellan air calorimeter, a soup-can shaped chamber the size of an industrial refrigerator that can precisely measure the heat that leaves an occupant’s body. Kenny had gone in the calorimeter before and after his trial, using it to measure how his body’s capacity to lose heat changed.

I then toured the lab’s other environmental chambers, including the one Kenny had done the trial in. That’s where I met some of the lab’s repeat trial participants. There was 69-year-old Bob Streicher wearing a hard hat and coveralls while walking quickly on the treadmill in 40C. Next door, 75-year-old Janet Spencer was passively resting in a t-shirt and shorts in 36C (96.8F). About an hour in, Spencer said: “My brain feels a lot mushier now.”

I could relate. By the end of the day, I’d sweat through my clothes, finished my water bottle and felt lightheaded when I returned to my hotel.

Today, after some brutally hot summer months in the Northern Hemisphere, my fellow reporter Aaron Clark and I tell the story of how Kenny and his colleagues are pushing their bodies to the limit to help save lives. 

Read it all in the Big Take on Bloomberg.com. 

Live experiment

Risks are increasing 

More from Green

It’s been a tough year for tourism boosters in Los Angeles. In January, devastating wildfires flared in Pasadena and Pacific Palisades, killing 31 people and destroying thousands of homes. With spring came the Trump administration’s immigration crackdown and the counterprotests that rippled through several neighborhoods. Amid the flood of disruptions, the nation’s second-largest city saw a dip in visitors. Luckily, they had a plan for that. 

According to the risk mitigation framework of the Los Angeles Tourism & Convention Board, the wildfires ranked as a “category 3 risk,” meaning they had the potential to impact visitation for up to half a year and wipe out 5% of the budget of the tourism promotion group, which is funded by local hotel taxes.

Through public records requests, Bloomberg CityLab obtained internal documents from more than a dozen state and local tourism entities that outline how to respond to various kinds of disasters. Volcanic eruptions, earthquakes and civil unrest are among the scenarios mentioned by the plans from cities like Atlanta and Austin.

The plans offer a rare look inside the tourism industry’s crisis management arm, which has grown in importance as climate-change-fueled disasters become more frequent and severe, along with social media’s ability to amplify and potentially distort them. In the wake of major incidents, local visitors bureaus mobilize to help keep brands intact and travel dollars flowing.

Read the full story on Bloomberg.com. 

Destroyed homes after the Palisades Fire in the Pacific Palisades area of Los Angeles in January 2025.   Photographer: Roger Kisby/Bloomberg

A Sierra Club employee filed a workplace misconduct complaint earlier this year with the board of directors alleging that then-executive director Ben Jealous engaged in sexual harassment and bullying. Reached for comment on the complaint, Jealous said in a statement he had been the victim of racial discrimination by the Sierra Club.

Exxon Mobil Corp. said net zero goals for the global energy sector are likely to drift further beyond 2050 due to consumers pushing back against high costs and a revival in demand for coal, the most polluting fossil fuel.

Commonwealth Fusion Systems raised $863 million from investors including AI giant Nvidia Corp. to help complete a demonstration system and continue development of its first commercial fusion power plant.

By Coco Liu

US battery makers will likely face a major surplus in manufacturing capacity by 2030 as President Donald Trump's administration withdraws support for electric vehicles, according to a new report.

The US is forecast to deploy nearly 378 gigawatt-hours of batteries by 2030, BloombergNEF said in a report published Thursday, 56% lower than the group’s forecast issued before Trump took office. It means the country’s battery makers face a looming overcapacity issue with 193 gigawatt-hours of batteries capacity online already and an additional 428 gigawatt-hours likely to be built out by 2030.

Meanwhile, battery makers are at risk of losing another type of buyer: power companies. Utilities in recent years have deployed large-scale batteries to avoid blackouts and store excessive output generated by renewable energy sources. Virtually non-existent a decade ago, utility-scale battery installations in the US reached a total of 26 gigawatts last year. In Texas alone, some 4 gigawatts of battery capacity — enough to power around 3 million homes — switched on in 2024.

But the Trump administration has announced rules that push energy storage project developers to steer clear of Chinese battery materials and components in order to qualify for tax credits, which will be hard for the industry. China dominates the global trade of battery components, with 88% of the world’s cathode and 96% of anode production capacity in 2024, according to BNEF.

Read the full story on Bloomberg.com. 

Low-carbon tech investments reached $2.1 trillion last year. But with the whole world trying to work out how to navigate US President Donald Trump’s unpredictable policy agenda, is 2025 still a good time to invest in climate tech? Back in May on Zero, Akshat Rathi interviewed Greg Wasserman, head of private company climate investment at Wellington Management, which oversees more than $1 trillion in assets. Wasserman weighed the risks and opportunities in a volatile market. Listen here, and subscribe on Apple, Spotify, or YouTube to get episodes of Zero every Thursday.

A panel of switches for the heat pumps and boilers. Photographer: Hollie Adams/Bloomberg

• Business of Food for a weekly look at how the world feeds itself in a changing economy and climate, from farming to supply chains to consumer trends
• Hyperdrive for expert insight into the future of cars
• Energy Daily for a daily guide to the energy and commodities markets that power the global economy
• CityLab Daily for top stories, ideas and solutions, from cities around the world
• Tech In Depth for analysis and scoops about the business of technology

Explore all Bloomberg newsletters.