On a recent Thursday evening, a freak wind storm called a derecho (Spanish for “straight”) hit Houston, a city of more than two million people that also happens to be the epicenter of the fossil fuel industry in America.
Within minutes, winds reaching 100 mph blew out windows of office buildings, uprooted trees and toppled utility poles and transmission towers. Nearly a million homes lost power. Which meant that not only was there no light, but there was also no air conditioning. The damage caused by the storm was so extensive that five days later more than 100,000 homes and businesses were still blocked by heat and darkness.
Fortunately, on the day the derecho hit, the temperature in Houston, a city infamous for its swampy summers, was in the high to mid 80s. Hot, sure, but for most healthy people it’s not life-threatening. Of at least eight deaths reported following the storm, none were due to heat exposure.
But if this storm had arrived several days later, perhaps during Memorial Day weekend, when the temperature in Houston reached 96 degrees, with a heat index as high as 115, things could have been very different. “The Hurricane Katrina of extreme heat,” is how Mikhail Chester, director of the Metis Center for Infrastructure and Sustainable Engineering at Arizona State University, once told me, echoing the memory of the catastrophic hurricane of 2005 which struck Louisiana and devastated New Orleans. and killed more than 1,300 people.
Most people who died in Louisiana during Katrina, died of drowning, injuries or heart problems. But Dr. Chester was using Katrina as a metaphor for what can happen to a city unprepared for extreme weather disaster. In New Orleans, the levee system was submerged by torrential rain; eventually, 80 percent of the city was underwater.
What if, instead, the electricity went out for several days during a scorching summer heatwave in a city that relies on air conditioning during those months?
In Dr. Chester’s scenario, a combined crisis of extreme heat and a power outage in a major city like Houston could lead to a series of cascading outages, exposing vulnerabilities in the region’s infrastructure that are difficult to predict and could result in thousands or even vulnerabilities. tens of thousands of deaths from heat exposure in just a few days. The risk to city dwellers would be higher because all the concrete and asphalt amplify heat, pushing temperatures up to 15 degrees to 20 degrees in the middle of the afternoon, above the surrounding vegetated areas.
The derecho that hit Houston was a warning about how quickly risks multiply in our rapidly warming world. As if to prove the point, about 10 days after the Houston blackout, another wind storm knocked out power to hundreds of thousands of homes and businesses in and around Dallas.
One of the most dangerous illusions of the climate crisis is that the technology of modern life makes us invincible. Humans are intelligent. We have tools. Yeah, it will cost money. But we can adapt to whatever happens to us. As for coral reefs bleaching in warm oceans and howler monkeys who fell dead trees during a recent heatwave in Mexico, well, it’s sad but life goes on.
This is of course an extremely privileged point of view. For one thing, more than 750 million people on the planet do not have access to electricity, and even less to air conditioning. (In India, New Delhi experienced temperatures of up to 120 degrees last week, leading to increased heat strokes, fears of power outages and the possibility of water rationing.) But it is also a naive point of view, if only because our bubble of invincibility is much more fragile than we think. So, what can we expect during a Katrina heat event?
Last year, researchers from the Georgia Institute of Technology, Arizona State University and the University of Michigan published a study examining the consequences of a major power outage during an extreme heat wave in three cities: Phoenix, Detroit and Atlanta. In the study, the cause of the failure was not specified.
“It doesn’t matter whether the outage was the result of a cyberattack or a hurricane,” Brian Stone, director of the Urban Climate Lab at Georgia Tech and lead author of the study, told me. “For the purposes of our research, the effect is the same.” Whatever the cause, the study noted that the number of major outages in the United States more than doubled between 2015-16 and 2020-21.
Dr. Stone and his colleagues focused on these three U.S. cities because they have different demographics, climates and reliance on air conditioning. In Detroit, 53 percent of buildings have central air conditioning; in Atlanta, 94 percent; in Phoenix, 99 percent. Researchers modeled the health consequences for residents of a two-day citywide power outage during a heat wave, with electricity gradually restored over the next three days.
The results were shocking: In Phoenix, about 800,000 people, or about half the population, are estimated to need emergency medical treatment for heatstroke and other illnesses. The flood of people seeking care would overwhelm the city’s hospitals. More than 13,000 people died.
In the same scenario in Atlanta, researchers found there would be 12,540 emergency room visits. Six people died. In Detroitwhich has a higher percentage of elderly residents and a higher poverty rate than other cities, 221 people would die.
Perhaps we shouldn’t be surprised by these numbers. Researchers estimate 61,672 people died in Europe from heat during the summer of 2022, the hottest season on record on the continent at the time. In June 2021, a heatwave successful in nearly 900 excess deaths in the Pacific Northwest. And in 2010, a estimated 56,000 Russians died in record summer heatwave.
The hotter it is, the harder it is for our bodies to cope, increasing the risk of heatstroke and other heat-related illnesses. And it’s getting hotter all over the planet. Last year was the hottest year on record, and the 10 hottest years have all occurred over the last decade.
In the study simulating a heat wave in these three cities, researchers found that the much higher death toll in Phoenix was explained by two factors. First, modeled temperatures during a heatwave in Phoenix (90 to 113 degrees) were much higher than temperatures in Atlanta (77 to 97 degrees) or Detroit (72 to 95 degrees). Second, the greater availability of air conditioning in Phoenix means the chances of a power outage during a heat wave are much higher.
Much can be done to reduce these risks. Building cities with less concrete and asphalt and more parks and trees and access to rivers and lakes would help. So would a more sophisticated, nationally standardized heat wave warning system. Large cities must also identify the most vulnerable residents and develop targeted emergency response plans and long-term heat management plans.
Making the network itself more resilient is just as important. Better digital firewalls in network operations centers thwart hacker intrusions. Burying transmission lines protects them from storms. Batteries to store electricity in an emergency are getting cheaper and cheaper.
But the hotter it gets, the more vulnerable the grid becomes, even as electricity demand increases because customers are running their air conditioning at full blast. Transmission lines sag, transformers explode, and power plants fail. A 2016 study found that the risk of cascading grid outages across Arizona increased 30-fold in response to a 1.8 degree increase in summer temperatures.
“Most grid problems on hot days come from outages at power plants or on the grid caused by the heat itself, or from difficulty meeting high demand for cooling,” Doug Lewin, grid expert and author of Texas Energy and Power newsletter, said. The best way to solve this problem, Lewin argued, is to encourage people to reduce electricity demand in their homes through high-efficiency heat pumps, better insulation and smart thermostats, and to produce their own electricity with solar panels and storage batteries.
The looming threat of heat Katrina reminds us how technological progress creates new risks while solving old ones. On an extremely hot day during a recent trip to Jaipur, India, I visited an 18th-century building with an indoor fountain, thick walls, and a ventilation system designed to channel wind in every room. There was no air conditioning, but the building was as cool and comfortable as a new office tower in Houston.
Air conditioning may indeed be a modern necessity without which many of us who live in hot parts of the world cannot survive. But it is also a technology of forgetting. Once upon a time, people understood the dangers of extreme heat and devised ways to live with it. And today, as temperatures rise due to our rampant consumption of fossil fuels, tens of thousands of lives could depend on remembering how it was done. Or find better ways to do it.
