The US power sector could release 42 percent more planet-heating carbon dioxide pollution by 2030 than it did in 2025 as it builds out more fossil fuel infrastructure to meet data center electricity demand, according to a new analysis by the Sierra Club. That would essentially wipe out 15 years of greenhouse gas reductions.

CO2 emissions from electricity generation would increase by 618 million tons by the end of the decade if planned AI projects are constructed. That’s roughly equivalent to carbon pollution from the electricity use of 128,788,523 homes in a year.

The Sierra Club’s estimate is higher than some previous projections from other groups. Another study published by academic researchers in June forecast that electricity demand from data centers and crypto mines could push up power sector emissions by 28 percent by 2030 when compared to a scenario with no data center growth. The outcome depends on how many planned data center projects actually come to fruition, as well as on what type of technology is used to power those facilities.