Microsoft’s greenhouse gas pollution increased about 25 percent last year, the company says in its new sustainability report released Thursday.

The report follows similar ones published by Google and Amazon last week. Together, they show a worrying trend of rising emissions from technology companies, driven by the global race to build energy-intensive data centers.

In a blog post announcing the report, Microsoft Vice President and President Brad Smith and Chief Sustainability Officer Melanie Nakagawa say the increase in emissions is “primarily due to the expansion of our data center infrastructure.”

A significant part of that increase, they write, was linked to emissions from the energy that the company purchased or acquired to run its operations. Known as Scope 2 emissions, that greenhouse gas pollution accounted for 13 percent of Microsoft’s total.

Data centers, which use large amounts of energy to run artificial intelligence chips, have put the net-zero emissions goals of many big technology companies increasingly out of reach in recent years.

Amazon revealed a 16 percent increase in its CO₂ emissions in its recent sustainability report. Google said in its new sustainability report that annual greenhouse gas emissions rose 18 percent last year compared to 2024, the largest single-year increase it has ever recorded. The company has invested aggressively in renewable energy, but has also begun adding fossil fuel power for some of its data centers.

Microsoft highlighted in its sustainability report that it had matched 100 percent of its electricity consumption to carbon-free sources. But data center construction will accelerate, and some of Microsoft’s recent investments could increase its emissions. Notably, the new report covers fiscal year 2025, which ended last June, and has since made a number of deals involving gas-powered data centers.

Last month, the company officially announced a partnership with Chevron, which is building a power plant to power a future data center for the company in West Texas. The permits show that this plant could emit more than 11.5 million tons of CO₂ equivalent annually, an amount greater than the entire state of Rhode Island. The company has also leased buildings at the Stargate campus in Abilene, Texas, which will be powered by an on-site power plant that could emit more than 7.8 million tons of CO.₂ equivalent each year. Microsoft also signed a non-binding letter of intent for computing at a West Virginia data center, which would be powered by off-grid gas that could emit more than 11 million tons of greenhouse gases.

“Microsoft’s strategy includes exploring a variety of options to mitigate emissions from its electricity consumption, consistent with our sustainability ambitions,” Nakagawa says in a statement to WIRED.

Microsoft’s approach to offsetting some of its emissions through credits and other investments is also changing. The company says it stopped purchasing unbundled renewable energy certificates, a move that partly contributed to the rise in Scope 2 emissions. The use of these types of certificates has been criticized in recent years as greenwashing because they do not necessarily add more clean energy to the grid. Disaggregated RECs are essentially a “paper transaction that is physically disconnected from real-world consequences,” says Danny Cullenward, a researcher at the University of Pennsylvania. (Cullenward is also a visiting Google faculty member, but notes that he was not speaking on behalf of the company.)

“I think it is very commendable that [Microsoft] “It is moving away from unbundled RECs and prioritizing investments in new clean electricity, where power purchase agreements and other long-term consumer agreements can and do trigger new clean electricity coming online,” he adds.

Despite rising emissions and its continued investments in AI, Microsoft still says it plans to become “carbon negative” by 2030. Smith and Nakagawa write that the global race for AI is “increasing demand for… energy, water, land and materials.” They say the company “has a responsibility to help ensure that technology strengthens, rather than burdens, the systems and communities it depends on.”