Myth check: “Data centres create heat islands that warm 340 million people”
The 2 °C figure comes from an unreviewed preprint. A peer-reviewed Tokyo study found daytime cooling and says waste heat falls 6–43× short.
What the data shows
The claim: AI data centres warm the land around them by about 2 °C on average, so the heat reaches the 340 million people living nearby.
What’s true. In March 2026 Andrea Marinoni of the University of Cambridge and colleagues posted a preprint (a paper not yet peer-reviewed) built on satellite readings of land-surface temperature. It reports a rise averaging about 2 °C after a data centre starts running, up to 9 °C in extreme cases, felt up to 10 km away. CNN reported it on 30 March. Waste heat is also real close to the source: a Phoenix study the new paper cites measured 0.7–0.9 °C of extra air warmth a few hundred metres downwind.
What the data shows. Jiawei Jing, of Makuhari Development Corporation in Chiba, published a peer-reviewed test in Environmental Research Letters on 4 November 2026. It follows twelve data centres built between 2011 and 2025 near Tokyo, using Landsat, ECOSTRESS and MODIS satellite data against matched control areas. Opening a facility cooled daytime land-surface temperature by 1.8–2.2 °C, the opposite of the claim. Night-time warming across the whole cluster stayed under 0.3 °C. An energy balance gives the main argument: a 2 °C rise, even in air, would need 6–43 times the waste heat available. In Phoenix and DeKalb, night surface warming was already in place during construction, before any servers ran.
What it means
The paper concludes that waste heat cannot warm land kilometres away at the size the preprint reports, so the 340 million figure rests on a premise it rejects. Heat near a facility’s cooling vents is real but local. Whether the buildings themselves change local surface temperature is a separate question this result does not settle.
Caveats
- This is one paper on one cluster, near Tokyo, and the preprint covered more than 6,000 data centres worldwide. A different region could differ.
- The author works for a company, Makuhari Development Corporation, not a university. We read the abstract and the publisher’s news release, not the full text, so funding and competing interests are unchecked. We found no published reply from the preprint’s authors.
- Land-surface temperature is the temperature of ground and roofs seen from space, not the air people feel. The 6–43× figure is a calculation, not a measurement at the preprint’s sites.
- The preprint is on its third version (April 2026) and may change.