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— Greg Harman
SAN ANTONIO, Texas—On Tuesday, the official high in San Antonio was 98 degree Fahrenheit. But, as folks who follow Deceleration know, that doesn’t mean squat for those in the urban core, where all this concrete and asphalt and unceasing highway traffic amplify the heat of summer. When the temps reported by the meteorologists click into the danger zone, we have to protect ourselves. Because we know that temperatures where we live can be 10 degrees hotter—or more—than the official numbers.
While 98F was logged in the shade at San Antonio International Airport, my street briefly hit 107.
At Deceleration we think a lot about the heat. For good reasons.
When our neighbor Albert Garcia died in 2023, we measured his old camp site at 114 during the day when the official temp was 105. And when our friend Jessica Witzel died during an extreme heat event in the summer of 2024, the temperature at the site of her death was 106F. But just one day before, I recorded downtown temps of 119—just a few miles away from where she died—and a heat index of a dizzying 129.
Heat at Albert Garcia's former campsite in 2023 (left) and temperature recorded the following year one day before Jessica Witzel's death in the Five Points area of San Antonio.
Extreme heat driven by the combustion of fossil fuels and destruction of global forests strains our power grid. It drives up our energy bills. And it claims lives.
While temps in Texas have been rising steadily in recent decades, cities like San Antonio are investing in policies in try to dampen the heat’s impacts. Tree planting campaigns, “cool” pavement programs, preservation of greenspace, encouraging rideshares.
But how would you respond if massive industrial facilities that excel in pushing out superheated air moved into the neighborhood? What if they were suddenly popping up across your community, threatening to undermine all of your best heat work?
It turns out hyperscale data centers aren’t merely gluttons for water and power; they are also frequently generators of massive heat islands, raising area temps on average around 4 degrees Fahrenheit.
And sometimes much more.
We wanted to see what that looked like in San Antonio, Texas.
Deceleration Video
The official temp was 98°F but in the shadow of a clutch of large data centers in San Antonio the temps cranked up to 112°F. This investigation explores the urban heat island effect and reveals how massive data centers are contributing to an escalating heat emergency. Follow Deceleration on YouTube.
Survey!
SA Climate Ready 2035 Survey: 'A Priority Plan for a Climate Ready San Antonio'
The extreme heat and storms associated with global warming are already unraveling human and ecological societies across broader swaths of the planet. U.S. cities are far from immune.
“What we're seeing in some parts of the city is: it's very unlivable, in a way, during certain months of the year,” said Jennifer Brady, senior data analyst and research manager at Climate Central. She heads the nonprofit’s data-driven investigations into climate trends and impacts.
“It's going to become really unmanageable to be outside at the very least,” Brady said. “Like, how can people live in cities and go outside their homes? And then you see places like Phoenix where they're thinking about, you know, 3 or 4 months a year, how does a city function in this heat?
"On top of this, we must now consider the heat being pushed out around the clock by data centers. Facilities that are actively, in Brady's words, “creating more spaces where that [ie. livability] might be a challenge and a question.”
The most significant paper we found on data center-generated heat was produced by an international team of researchers from a collection of universities and research institutions. The group reviewed decades of heat data for their study and considered data centers across the planet. To weed out other potential influences, they isolated large scale (or hyperscale, to use industry parlance) data center operations in rural areas.
Their finding?