The record-setting heat wave in Phoenix this summer, thirty-one consecutive days of temperatures exceeding a hundred and ten degrees, finally broke on Monday, July 31st. But, by the following Friday, August 4th, the thermometer was creeping up toward a hundred and fifteen degrees. Residents liked to joke that anything below the “teens” was comfortable. Jessica Lindstrom, who was thirty-four, was no longer a resident. She and her husband, Daniel, had bought a house in Central Point, Oregon, in 2015. But she had grown up in greater Phoenix and, that week, had brought her expanding family to Arizona to stay with her parents. The next day, they were going to celebrate the baptism of their second-oldest son, in the chapel of the Church of Jesus Christ of Latter-day Saints.
Lindstrom was relieved to have her parents’ help. She might not have wanted to admit it—she could be a perfectionist, and her family called her a supermom—but she was exhausted. In Oregon, not only was she raising four young sons (her oldest was just ten) but she was also a nurse, working night shifts at a hospital, in an in-patient rehab. In between, she ran the children’s religious-education program at her local church. Her husband worked full time as a pharmacist. So, that Friday morning, happy to be home, back in the desert, she decided to take some time for herself. At 8:30 A.M., while her parents watched the kids, she headed to the nearby Deem Hills Recreation Area—a small mountain, scratched over by hiking trails.
Deem Hills covers nearly a thousand acres of the Sonoran Desert, and is known for its unique basalt volcanic-rock formations. The rock holds the heat, meaning that the ambient temperature, what Lindstrom actually felt, could have been ten degrees hotter than that day’s high of a hundred and fifteen. The longest trail—a circumference of the entire ridge—is just under six miles. Lindstrom had hiked these hills countless times. She loved the open sky, the desert colors, the towering saguaros, with their arms open wide. She loved the quiet, and the sense of peace she felt, nestled in the tiny valleys, or when she stopped to take in the view, looking out over her home town. One of the hike’s orienting landmarks was the steeple of a Latter-day Saints temple. Daniel, who is from California, often hiked with her there after they started dating, and he grew to love the hills, too. On a hike in 2012, he got down on one knee, and, “in the corniest possible way,” as he described it to the family later, asked Lindstrom to marry him.
Daniel, an élite runner (he was on the cross-country team at the University of California, Riverside, and had completed several marathons), had gone running in Deem Hills earlier that morning. Lindstrom met him at the park before her run, and he continued to his in-laws’ house. She left her phone in her car. Her long brown hair was pulled back in a ponytail, and she wore a black tank top, neon-yellow shorts, and sneakers.
Around 10 A.M., the family grew concerned that Lindstrom hadn’t yet returned. Daniel and two of Lindstrom’s brothers went to check on her. By eleven-thirty, her father, David Adams, and her third brother had joined the search. Her mother called 911. A member of their church is a captain with the Phoenix Police. He quickly organized a search party with the fire department, using helicopters, drones, and men on the ground. The police posted a missing-person sign online, and social media filled with calls for volunteers. Adams called his only daughter Peanut, but Lindstrom was a strong athlete, tough and persistent. It seemed unimaginable that she could have just vanished.
Globally, about half a million people die from heat-related causes every year, according to a 2021 study published in The Lancet Planetary Health. Across the U.S. each year, significantly more people die from heat than from any other weather-related event, including hurricanes, tornadoes, floods, and even rip currents. Many of these deaths are concentrated in and around Phoenix. In 2022, there were four hundred and twenty-five heat-associated deaths in Maricopa County—a twenty-five-per-cent increase from the previous year. The impacts of this year’s heat wave are still being analyzed. But, for everyone who lived through it, this was a relentless thirty-one-day emergency, with no respite. “We’ve hit these highs before,” Nick Staab, the assistant medical director for Maricopa County’s Department of Public Health, told me. “But now, it’s just not having a break. The human body needs an opportunity to cool down.”
People have inhabited and thrived in the Sonoran Desert for centuries. In 1050, the Sinagua, a name that came from the Spanish, meaning “without water,” made cliff dwellings in the Verde Valley, just ninety minutes north of central Phoenix. Their homes and structures were constructed with wood, stone, and mud and built into the walls of a limestone ravine, extending through a system of caves, which tend to be cooler than the outside air in the summer. The ravine walls faced south, meaning the dwellings would have stayed warm in the winter. In the nineteen-seventies, an Italian architect named Paolo Soleri built his own south-facing labyrinthian cliff dwelling into the side of a mesa outside Phoenix, hoping to construct a new kind of ecologically and desert-mindful city. Arcosanti, as he named it, still exists, with some fifty residents, and tourists year-round. But Soleri’s vision seems as lost as that of the Sinagua.
In the early twentieth century, the invention of air-conditioning allowed a city to grow rapidly, in ways that no longer heeded the desert heat. In recent decades, farm fields and open desert have been replaced by roads, parking lots, cars, strip malls, and endless subdivisions, leading to an urban heat island, which compounds the effects of the climate crisis. Maricopa County, which contains Phoenix and more than two dozen other cities, towns, and tribal communities, is now the fourth most populous county in the United States. Phoenix is the fifth-largest city in the U.S., and the hottest large city, with an average summer temperature of 93.7 degrees—an average that has increased by 3.8 degrees since 1970. Nighttime summer temperatures, largely owing to urbanization, now average a low of eighty-three degrees, an increase of 5.4 degrees since 1970. Even the saguaro cacti, which are endemic to the Sonoran Desert, can’t cool off enough at night. They have been dropping their arms and falling down.
And, yet, people continue to flock to Maricopa County, the fastest-growing county nationwide last year. People might dislike the summertime heat, but it’s a small price to pay for the other eight gorgeous months of the year. “The key, for the summer, is not to be here,” a Phoenix firefighter and lifelong resident told me.
People who can’t afford to leave must adjust. Runners and cyclists invest in headlamps and glow-in-the-dark gear. Construction workers start their days at 4 A.M., bringing in giant floodlights to work sites. Since pools get too hot for swimming, homeowners buy giant ice blocks for pool parties. Pedestrians carry parasols. Parking attendants sit outside next to swamp coolers. Restaurants and bars deploy fans and misters, shrouding their patios in a cool fog. (In deep summer, even the misted patios are empty.) One outdoor bartender told me that fans under the bar “keep us alive, mildly. And tequila shots.”
The streets seem abandoned, save for the unhoused. People go from air-conditioned houses, to air-conditioned cars, to air-conditioned offices, stores, schools, or camps. They get used to seeing their car dashboard thermometer read a hundred and twenty if it’s parked in the sun in the afternoon. They take care not to sear themselves when touching car-door handles. (I burned my leg on the side of a car door.) Shade becomes sacred. “It’s kind of the opposite of how other areas hibernate,” Sonia Singh, a spokeswoman for the Department of Public Health, told me. “We go outside in the winter and come inside during the summer.”
Still, this summer, which included the hottest July ever recorded on the planet, has been different. Not only were the days scorching but there was a stretch of sixteen days when the nighttime low was ninety degrees or above, including one night when the low was ninety-seven degrees. Summer is supposed to be monsoon season in Arizona, but by mid-August the Phoenix Sky Harbor International Airport hadn’t recorded measurable rainfall in a hundred and forty-seven days. Arizona’s only burn center, situated in Phoenix, was full of patients who had fallen on the ground and burned their skin. The Maricopa County Department of Emergency Management took to holding “FRYdays” on Twitter, cooking various foods—cookies, pizzas, roasted red peppers—on dashboards, to show how hot a car’s interior can get, in a lighthearted effort to remind people to avoid the heaviest kind of risk, a calamity that continues to happen: pets and children being left in hot cars.
The city of Phoenix established an Office of Heat Response and Mitigation, the country’s first publicly funded city-government office working on heat, in 2021, and appointed an energetic young scientist named David Hondula to run it. (Miami and Los Angeles also have chief heat officers.) “We’re writing a playbook for jobs that haven’t existed before, and we’re trying to do so as quickly as we can,” Hondula told me. “Obviously what we’ve experienced this summer is not anything the region has experienced before.”
As temperatures increase worldwide, heat’s invisible danger will threaten more and more people. By 2030, according to a new climate analysis from the Washington Post and the nonprofit CarbonPlan, four billion people will be exposed to at least a month of extreme heat. (In dry climates, like Phoenix, that could mean a month of days reaching a hundred and twenty degrees Fahrenheit or higher.) By 2050, that number will increase to five billion, or more than half the planet’s population. So far, the Maricopa County Office of the Medical Examiner has confirmed a hundred and eighty heat-associated deaths this year, with three hundred and thirty still under investigation. Both numbers are much higher than those at the same time last year, despite a lag in the data, since it takes about six weeks for the O.M.E. to conclude a death investigation. The O.M.E.—already one of the busiest medical examiner’s offices in the U.S.—has been overwhelmed.
One morning in August, I arrived at the Forensic Science Center, the O.M.E.’s headquarters, to meet with Jeff Johnston, the chief medical examiner, who was rail-thin, wearing black-rimmed glasses, a gray beard, and a gray suit. He spoke about his work softly and kindly, with a subtle drawl, having grown up in the Southeast. He did his pathology residency at the University of Tennessee, in Knoxville, and worked in the university’s forensic-anthropology facility (commonly known as the Body Farm). He saw his profession—which, to his great frustration, is struggling to recruit enough people—as a critical form of public service. “By understanding what people died from,” he told me, “we can have this huge impact on preventing future deaths.”
Johnston was accompanied by one of his investigators, a wide-eyed twenty-six-year-old named Emily Sprague, who had very long, straight blond hair. They both carried giant water bottles. Sprague’s job is to take a report about a decedent from the first responders, then drive to the scene, investigate the environment and the body, and coördinate the return of the body to the Forensic Science Center. (On such trips, Sprague and the office’s other death investigators wear “cool” vests, which have pockets stuffed with ice packs.) “We’ve just gone through a historic surge,” Johnston said. “We had to push everybody to the limit in order to respond.” This meant they had less time to find and notify next of kin. If they couldn’t release bodies, their refrigerators were at risk of filling up. At the end of July, as an emergency precaution, the office trucked in portable refrigerators, as it did during the city’s worst COVID surge. (In the end, the office did not need to use them.)
Heat illness happens in two ways. The first is classic heatstroke, a result of prolonged heat exposure, which typically strikes infants; the elderly; those who are overweight; and unhealthy, sedentary adults, who may be suffering from other chronic conditions such as cardiovascular disease, diabetes, or hypertension. It’s what kills a person stuck in a house with malfunctioning air-conditioning on a summer day. The second type of heat illness is exertional heatstroke, which occurs during physical activity. “So you can get this,” Johnston said, pointing at me. “Anybody can get this.” The risks are highly individualized. Respiratory problems, prescription or over-the-counter drugs, alcohol, even scars on the body, can affect how a person regulates heat. Young, fit people, such as long-distance runners, are more capable of warding off the warning signs of heat illness until, sometimes, it’s fatally too late. Acclimatization matters. In the desert, for instance, visitors are not only unaccustomed to the heat, they don’t realize how much fluid they are losing just by breathing and talking in the dry air, which leads to dehydration, then reduced blood volume, exacerbating heat exhaustion.