The rapid expansion of data centers in the United States could undermine years of progress in reducing greenhouse gas emissions, according to a new assessment by the Sierra Club. The organisation warns that electricity demand from planned facilities may drive a sharp increase in power-sector pollution by the end of the decade.

The assessment projects US power-sector CO2 emissions could reach 2.1 billion metric tons by 2030, 42% above 2025 levels. It also estimates that emissions associated with the expansion could exceed 460 million metric tons by that year, a volume comparable to Mexico’s annual CO2 emissions. Sierra Club climate and energy adviser Jeremy Fusher said the scale of the estimates was striking; the organisation’s earlier calculations put the projected increase between 25% and 50% of its current estimate.

Natural gas is already a significant source of electricity for data centers: gas turbines supply power to roughly 40% of US facilities. Meanwhile, renewable generation is struggling to keep pace with fast-growing demand. Turbine prices have risen by 50%, and manufacturers face backlogs stretching several years, with some equipment reservations reportedly scheduled for delivery in 2032. These delays could lead developers to rely on fossil-fuel generation rather than wait for renewable power or expanded grid infrastructure.

The assessment also points to limits on how quickly proposed projects can be built. Permit applications exceed available transmission capacity in some locations, while grid connections and other infrastructure constraints could delay developments. Some projects face community opposition over electricity use, environmental effects and the cost of infrastructure expansion. Financial uncertainty in the AI industry may also prompt hyperscalers to postpone or abandon projects.

Renewable-energy rules for new facilities could help limit emissions, but the assessment notes that such requirements can allow time for implementation and generally do not apply retroactively to existing data centers. Ireland, for example, requires new data centers to source 80% of their electricity from renewables within six years of starting operations. The timing and scale of US data center growth, and its eventual effect on emissions, therefore remain uncertain.

Sources: TechRadar.