In a nutshell: Data centers have already drawn widespread resistance over their impact on electricity prices and water supplies, and estimates of how their energy use might affect carbon emissions have recently grown. Still, projections vary widely, owing to uncertainty over renewables and over how many data centers will actually be built in the next several years.
In a report obtained by Bloomberg, the environmental nonprofit Sierra Club estimates that planned US AI data centers would add 618 million metric tons to the power sector's carbon emissions between 2025 and 2030, a 42% increase. The figure would effectively reverse 15 years of greenhouse gas reductions from electricity generation.
Adding that much CO2 would bring the sector's 2030 emissions to 2.1 billion metric tons. The latest estimate of the AI buildout's effect is between two and four times what the group would have projected a year and a half ago.
Many of these data centers are turning to new power sources of their own to avoid waiting to plug into existing grids. While that might ease the strain on residential grids and electricity prices, these off-grid sources could add more than 460 million metric tons of emissions, roughly equal to Mexico's annual emissions.
Estimates remain far apart, though: the gap between the lowest and highest projections exceeds the combined electricity demand of California and Florida. One reason is that renewables could supply much of the new buildout. Rhodium Group, for example, finds that even in its highest-emission scenario, the power sector's 2040 emissions would fall 24% below 2025 levels.
There is still no guarantee that all currently planned data centers will actually be built.
There is also no guarantee that every planned data center will actually be built. Earlier this year, Sightline Climate estimated that between one-third and half of the US data centers slated to open this year will be delayed or canceled.
Struggles to meet AI's power demands have already slowed the deployment of data center GPUs. Amazon and other companies are reportedly letting "dark GPUs" sit unused until the data centers meant to house them have the power to run them.
Amazon's planned Texas data center, meanwhile, would be fed by a 7.65-gigawatt natural gas plant permitted to emit up to 33 million tons of CO2 a year, which could make it the largest single source of CO2 emissions in the US.
Carbon emissions are just one reason data centers are increasingly controversial in the US. Residents of communities near data centers often complain about electricity prices, noise, water pollution, and impacts on property values.
The AI buildout's carbon bill could undo 15 years of power sector emissions cuts
