Do datacenters generate more greenhouse gas than aviation?
And if not... will AI-fueled growth change that in the next few years?
The WEF says yes
As a representative example of numbers quoted about the environment impact of data centers, the World Economic Forum says “data centres (responsible for 2.5% of all human-induced carbon dioxide) have a greater carbon footprint than the aviation industry (2.1%).”
The data say NO
In 2023, data centers were responsible for around 1.2% of global carbon footprint, whereas aviation was responsible for 2% (or more if you include the impact of contrails).
Using US data and projecting through 2028 using aggressive forecasts due to AI, it’s possible that data centers will start to get close to aviation:
Here’s how I came up with these numbers…
Aviation
According to the US EIA, jet fuel was responsible for 247 million metric tons of CO2 in 2023. So aviation represents 3.9% of the US total of 6.3 billion mtCO2e. Assuming a 7.3% CAGR, in 2028 jet fuel will be responsible for 351 million metric tons, or 6.1% of projected US emissions of 5.8 billion mtCO2e.
Recent research has shown that the climate impact (GWP) of aviation is about three times higher than the CO2 used due to contrails and nitrogen oxide emissions. So the GWP of aviation is the equivalent of 727 million mtCO2 vs , or 10.6% of US warming potential if you include the impact of contrails.
Electricity
Let’s do the math using this data from the EIA.
In 2023, 4,183 TWh were generated and resulted in 1.5 billion metric tons of CO2, or 0.36 million mtCO2 per TWh. Including the warming impact of nitrogen oxide (305 million mtCO2e), the GWP of US electricity generation is 0.44 million mtCO2e per TWh.
According to the EIA, planned generation changes by 2028 will reduce the amount of coal on the grid by about 20% and increase solar and wind by 30%. That would reduce the GWP by approximately 10%, to around 0.4 million mtCO23/TWh.
Datacenters
Per my previous post about datacenter energy use, in 2023 data centers used 176 TWh of electricity, and in 2028 may use as much as 580 TWh. Using the above numbers, plus 25% for embodied emissions from production (though technically these aren’t happening in the US), datacenters were responsible for 97 million mtCO2e or 1.5% of US emissions in 2023 and around 288 million mtCO2e, or 5.0%, in 2028.
Why do people keep getting this wrong?
If you follow the links on the WEF article, it ends up - as many of these numbers do - at a report produced by The Shift Project, which itself refers to data from a 2015 article. These are global numbers, but you can see from the % of electricity consumption that these are significantly higher than actuals - 2023 shows 4.8% of electricity use for datacenters, and also includes a very large number for production.
If we adjust these numbers based on US actuals (1.2% of electricity use) and a more realistic value of 25% of use for production, we would have a more realistic number of 510 million mtCO2e for 2023, representing 1.2% of global energy consumption - significantly less than the 882 million mt or 2.0% from aviation (not including contrails, which would increase the impact to almost 6%).
