Big Tech's data centers could add 101.5M tons of CO2 a year
The AI build-out's environmental bill is getting a number: the 60 biggest data centers under construction in the US would pump out over 100 million tons of CO2 a year — and the utilities feeding them are doubling down on gas.
A new analysis of the 60 largest data centers Amazon, Microsoft, Google and Meta are building in the United States puts their combined footprint at about 101.5 million metric tons of CO2 per year once fully operational — roughly 7 percent of the entire US power sector's 2025 emissions, equivalent to 27 coal-fired plants or 24 million gasoline-powered cars. The estimate, based on utility filings and data from S&P and analytics firm DC Byte, assumes the current US electricity mix, and the researchers behind it are careful to call it a rough figure rather than a forecast. Energy researcher Jonathan Koomey, who reviewed the work, put it plainly: "This is a reasonable rough estimate... the increase is still substantial compared with what data center operators were promising five years ago. They all had plans to reduce emissions."
The sharper finding is that the boom is actively bending the power grid back toward fossil fuels. Three-quarters of the utilities serving the 60 projects are planning or building new gas-fired capacity, a third of operators still running coal plants are postponing retirements, and 17 percent told regulators outright that the new gas exists to supply specific hyperscale facilities. Entergy Louisiana is building nearly 10 gigawatts of gas to serve a Meta campus, conceding that renewables can't yet carry that load alone, while other operators are going behind the meter with their own gas plants — the pattern we flagged in Amazon backs a 7.65 GW gas plant for an off-grid Texas AI campus. The trend shows up in the companies' own sustainability reports: Amazon's emissions rose 16 percent from 2024 to 2025 (with power-related emissions up 34 percent), Microsoft's rose 25 percent, and Alphabet's rose 18 percent.
The context makes it worse. US power-sector emissions rose about 2 percent last year with data centers a major driver, and the Trump administration is rolling back climate rules and clean-energy tax incentives at the same time — the political backdrop we mapped in The $1 trillion AI build-out hits a wall cash can't fix. Data centers now account for roughly 55 percent of utilities' five-year load forecasts, making them the single biggest driver of US electricity demand growth. Researchers like Aaron Bergman of Resources for the Future are blunt about the mechanics: "Whenever demand on the power system increases, emissions are also very likely to rise." The open question is whether the industry's promised multibillion-dollar clean-energy investments can catch up — or whether the AI build-out quietly ends America's long decline in power-sector emissions.
What to watch: whether utility regulators start conditioning data-center hookups on matching clean-energy procurement, and whether hyperscaler climate pledges survive contact with earnings season.
If data centers are set to add over 100 million tons of CO2 a year, should utilities be allowed to keep building gas to serve them? Tell us in the comments.
