Are data centers bad for the environment?

Emissions from electricity

The IEA estimates emissions from data center electricity at 180 million tonnes today, growing to 300 million tonnes by 2035 in its base case and up to 500 million in its highest case[1]. It says that remains below 1.5% of energy-sector emissions, but that data centers are among the fastest-growing sources[1].

What powers them matters. Globally the IEA expects renewables to meet nearly half of added data center demand over five years[3], but in the United States it projects natural gas as the largest source of new supply through 2030 (over 130 TWh), with renewables second (110 TWh)[3].

Independent estimates vary. A Harvard-led preprint estimated U.S. data centers produced more than 105 million tons of CO2e over a year ending August 2024, with a carbon intensity 48% above the U.S. average[4]. A perspective article in Patterns estimated AI systems alone could emit 32.6 to 79.7 million tons of CO2 in 2025[5]. Both are estimates with wide uncertainty.

What companies report

Google says that in 2025 it cut operational emissions 2% despite a 37% rise in electricity demand, while matching all its electricity with renewable purchases for a ninth year[6]. Axios reported the same year that Google's total emissions rose 18%, driven largely by manufacturing AI hardware[7]. Microsoft says it matched 100% of its FY25 electricity with renewables[8], while ESG Today reported its emissions rose 25% on AI infrastructure buildout[9]. Both things can be true: renewable matching covers electricity purchases, not the full footprint.

Backup generators and gas turbines

Data centers keep diesel generators for power outages. In Virginia, JLARC found nearly all current data centers use Tier 2 diesel generators, which state regulators allow to run only in emergencies or for maintenance testing, and that they make up less than 4% of regional nitrogen oxide emissions in Northern Virginia[10]. Virginia's environmental regulator has since concluded that generators permitted as emergency units will run for extended periods in some circumstances[11], and since July 1, 2026 has required Tier 4-equivalent standards for new or modified data center generators[12].

Some AI campuses generate their own power with gas turbines. EPA says turbines and engines used by data centers are subject to federal air standards[13]. In Memphis, the Shelby County Health Department permitted 15 gas turbines at xAI's data center with emission caps[14][15]; groups appealing that permit say up to 35 turbines were on site before permits were sought[15]. See the xAI Colossus record.

Land and water

JLARC counted over 63 million square feet of data center space on 7,200 acres in Virginia[10]. Water is covered in depth in our guide to how much water data centers use.

Efficiency gains

Data centers have become far more efficient per unit of computing. LBNL found U.S. data center energy use held steady at about 60 TWh from 2014 to 2016[16], thanks to better cooling and power management, higher server utilization and more efficient hardware[16]. Average PUE fell from 2.5 in 2007 to 1.65 in 2014[2], but has barely moved since, sitting at 1.54 in 2025[2].

Common questions

Are data centers bad for the environment?

They have real and growing impacts, mainly through electricity use. The IEA estimates data center electricity emissions at 180 million tonnes of CO2 today, rising to 300 million by 2035 in its base case, though still under 1.5% of energy-sector emissions. Local impacts include backup generators, gas turbines, land and water use.

Do data centers use renewable energy?

Some companies match their electricity purchases with renewable energy; Google and Microsoft both report 100% matching. In the U.S., the IEA projects natural gas will be the largest source of new data center supply through 2030, with renewables second.

Do data centers pollute the air?

Backup diesel generators and on-site gas turbines emit air pollutants and require permits. JLARC found diesel generators make up less than 4% of regional nitrogen oxide emissions in Northern Virginia.

Sources

1. Energy and AI – Executive Summary
   International Energy Agency (IEA) · 2025-04
   2 source excerpts

   “Emissions from electricity use by data centres grows from 180 million tonnes (Mt) today to 300 Mt in the Base Case by 2035, and up to 500 Mt in the Lift-Off Case.”

   “While these emissions remain below 1.5% of the total energy sector emissions in this period, data centres are among the fastest growing sources of emissions.”

2. Uptime Institute Global Data Center Survey 2025
   Uptime Institute · 2025-07
   2 source excerpts

   “In 2025, respondents' annual PUE had a weighted average of 1.54 (see Figure 2), marking the sixth consecutive year that this headline figure has virtually stood still.”

   “The industry's average dropped quickly — from 2.5 in 2007 to 1.65 in 2014 — as operators first deployed the most practical and economical changes.”

3. Energy and AI – Energy supply for AI
   International Energy Agency (IEA) · 2025-04
   2 source excerpts

   “Over the next five years, renewables meet nearly half of the additional demand, followed by natural gas and coal, with nuclear starting to play an increasingly important role towards the end of this decade and beyond.”

   “Natural gas is the largest source of additional supply, adding over 130 TWh of annual generation until 2030. Renewables are the second-largest source of additional electricity supply, adding 110 TWh to the data centre electricity supply between 2024 and 2030.”

4. Environmental Burden of United States Data Centers in the Artificial Intelligence Era (arXiv preprint 2411.09786)
   arXiv (Guidi, Dominici, et al., Harvard T.H. Chan School of Public Health) · 2024-11-14
   Source excerpt

   “Our findings reveal that data centers accounted for more than 4% of total US electricity consumption - with 56% derived from fossil fuels - generating more than 105 million tons of CO₂e (2.18% of US emissions in 2023). Data centers' carbon intensity - the amount of CO₂e emitted per unit of electricity consumed - exceeded the US average by 48%.”

5. The carbon and water footprints of data centers and what this could mean for artificial intelligence
   Patterns (Cell Press); author Alex de Vries-Gao · 2026-01
   Source excerpt

   “The carbon footprint of AI systems alone could be between 32.6 and 79.7 million tons of CO2 emissions in 2025”

6. Read Google's 2026 Environmental Report
   Google · 2026-06-30
   Source excerpt

   “Notably, despite navigating our largest load growth in history — a 37% annual increase in electricity demand — we successfully reduced our operational emissions by 2% year-over-year while matching 100% of our electricity consumption with renewable energy purchases for the ninth consecutive year.”

7. Google's AI boom sends emissions, power use soaring
   Axios · 2026-06-30
   Source excerpt

   “Greenhouse gas emissions rose 18%, the largest annual increase Google has reported, driven largely by manufacturing AI hardware, including chips and servers.”

8. 2026 Environmental Sustainability Report
   Microsoft · 2026
   Source excerpt

   “In FY25, we achieved our milestone to match 100% of our annual electricity consumption with renewable energy.”

9. Microsoft's Carbon Footprint Jumps 25% as AI Buildout Challenges Climate Goals
   ESG Today · 2026-07-13
   Source excerpt

   “Microsoft released its 2026 Environmental Sustainability Report, revealing a significant jump in the tech giant's GHG footprint, with emissions rising 25% over the prior year, driven by an accelerating AI infrastructure buildout”

10. Data Centers in Virginia (Report 598)
    Joint Legislative Audit and Review Commission (JLARC), Virginia General Assembly · 2024-12
    3 source excerpts

    “Nearly all current data centers use 'Tier 2' diesel generators, which DEQ allows to run only in emergencies or as part of routine maintenance testing.”

    “in Northern Virginia, they make up less than 4 percent of regional emissions of nitrogen oxides”

    “In total, Virginia has over 63 million square feet of data center space on 7,200 acres of land.”

11. Virginia DEQ Revises Data Center Generator Rules as Community Pushback Builds
    Data Center Knowledge · 2026-05-19
    Source excerpt

    “DEQ has also considered the permit history and operating profile for data center gen-sets that now strongly indicate that gen-sets permitted as emergency units will be operated for extended periods under certain circumstances.”

12. Data Centers: Noise & Air Quality Concerns
    Loudoun County, Virginia · 2026
    Source excerpt

    “On July 1, 2026, DEQ began mandating Tier 4-equivalent emissions standards for new or modified generators at data center sites.”

13. Clean Air Act Resources for Data Centers
    U.S. Environmental Protection Agency · 2026-09-14
    Source excerpt

    “Stationary combustion turbines and stationary engines – common sources of primary and backup power for data centers – are subject to various new source performance standards (NSPS) for certain air emissions and national emission standards for hazardous air pollutants (NESHAP).”

14. Health dept. grants permit for xAI turbines
    Action News 5 (WMC) · 2025-07-02
    Source excerpt

    “The health department's approval includes caps on the facility's 12-month rolling emission rates, which xAI is required to record and maintain monthly.”

15. NAACP, others appeal xAI turbine permits for Memphis data center
    Tennessee Lookout · 2025-07-17
    2 source excerpts

    “The NAACP and another group are challenging the Shelby County Health Department's decision to grant xAI an air permit for 15 gas turbines at its South Memphis data center, according to an appeal filed Wednesday.”

    “The groups allege that the campus had up to 35 gas turbines on site capable of generating more than 420 megawatts of electricity before it sought permits.”

16. 2024 United States Data Center Energy Usage Report
    Lawrence Berkeley National Laboratory · 2024-12-20
    2 source excerpts

    “U.S. data center annual energy use remained stable between 2014–2016 at about 60 TWh”

    “The efficiency strategies that allowed the industry to avoid increased energy needs during this period included improved cooling and power management, increased server utilization rates, increased computational efficiencies, and reduced server idle power.”

Each source was opened and checked against the excerpt shown. Company statements are identified as such. Figures are as published; where sources differ, each is shown.