U.S. Cities at Risk for ‘Deadliest’ Heat Wave-Power Failure Combo

Millions of urban Americans will be put at serious risk of heat exhaustion this summer if any heat waves coincide with power failures—a deadly conjunction that is increasingly likely, says a new study.

“Power failures have increased by more than 60% since 2015, even as climate change has made heat waves worse,” writes the New York Times, citing research just published in the journal Environmental Science & Technology.

Using computer modelling to study the impacts of a combined heat wave and power failure on three representative U.S. cities—Atlanta, Detroit, and Phoenix—a team of American and Canadian researchers found that such a combination “would expose at least two-thirds of residents in those cities to heat exhaustion or heat stroke.”

While all three cities run cooling centres for those in need, they added, such shelters “could accommodate no more than 2% of a given city’s population…leaving an overwhelming majority of residents in danger.”

The concurrence of a widespread power failure during a heat wave is “maybe the deadliest climate-related event we can imagine,” said study lead Brian Stone Jr., a professor at the School of City & Regional Planning at Georgia Institute of Technology. And that lethal alignment is “increasingly likely.”

Heat waves are already exceedingly dangerous, “by one estimate killing some 12,000 Americans each year,” notes the Times. Meanwhile, the climate crisis “seems to be making power failures more common.”

According to Stone, the number of blackouts occurring annually in the U.S. doubled between 2015 and 2020. Pointing to the dangerous feedback cycle in play, the Times reports that “those blackouts were more likely to occur during the summer, suggesting they were being driven in part by high temperatures, which increase demand on the electrical grid as people turn up their air conditioners.”

In a global first, Stone and his team modelled just how hot homes would become if blackouts disabled air conditioners in the cities they studied. Detailing the “alarming” results, the Times writes that more than 350,000 Atlanta households—about 70% of residents—“would be exposed to indoor temperatures equal to or greater than 32°C, the level at which the National Weather Service’s heat classification index says heat exhaustion and heat stroke are possible.”

In Detroit, more than 450,000 people, or about 68% of the population, would suffer the same, while virtually everyone in Phoenix (where dependence on air conditioning is nearly universal) would find themselves at mortal risk.

While the study is a stark warning for citizens with air conditioning, the study authors also point out that many Americans lack any air conditioning at all. That lack of protection “is most pronounced for the lowest-income households, who are 20% less likely to have central air conditioning than the highest-income households.”

The study also documented the lack of backup power generators in any of the cooling centres surveyed.

Stone told the Times that, adding together studies by other researchers, “we find that millions are at risk”—not years in the future, he added, “but this summer.”