Japan Data Centers Did Not Heat Up Surroundings, Study Finds

At the facilities at the center of the analysis, and after accounting for temperature changes in comparison areas, daytime surface temperatures were 1.8 to 2.2°C lower after operation began than before construction. The researchers attribute this to the buildings' roofs, which reflect more sunlight than the farmland and vacant lots they replaced, so the surface warms less.

Nights and earlier findings

The question is harder at night, when the sun no longer masks server heat. Even so, in areas a few kilometers across where several of the studied facilities cluster, the rise in nighttime surface temperature was reported to be small.

An earlier study had reported an average surface temperature increase of about 2°C within up to 10 km of data centers. The new work estimates that producing a rise of that size from server waste heat alone would require 6 to 43 times the heat the facilities can actually release. That makes it difficult to explain such a widespread increase through waste heat alone.

What the study does not show

The findings do not prove that data centers leave their surroundings unaffected. Satellites measure the temperature of surfaces such as ground and roofs, not the air temperature people feel. A separate study near Phoenix, Arizona, recorded air temperatures averaging roughly 0.7 to 0.9°C higher, and up to about 2.2°C higher, within a few hundred meters downwind of facilities compared with upwind.

Waste heat does not vanish, and residents living nearby are not necessarily unaffected. But as AI drives data center construction worldwide, the research suggests it is too simple to say that the heat they produce will markedly warm entire surrounding cities.