Don’t worry about the carbon footprint of your emails

If governments want to clean up the internet, there are bigger problems than the number of emails people send.
If governments want to clean up the internet, there are bigger problems than the number of emails people send.
Image: REUTERS/Callaghan O'Hare
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What if minor changes to the way we use email could add up to significant cuts to the world’s carbon footprint?

That question is on the mind of officials in the UK who are currently hammering out policy options for next year’s major global climate summit in Glasgow, according to the Financial Times. The officials, FT reports, are taking a close look at research produced last year by UK-based renewable energy provider Ovo Energy that attempts to add up the carbon footprint of “unnecessary” one-word emails, like “Thanks” or “Cheers.” The central finding is eye-catching: If every person in the UK sent one fewer such email per day, it would amount to the same carbon reductions as canceling 81,152 flights from London to Madrid.

So could, in fact, a government crackdown on throwaway emails be an easy way to score some carbon policy points? To put it in one word: No.

Mike Berners-Lee, the environmental economist at Lancaster University whose work on the carbon footprint of computing Ovo cited as the basis for its analysis, tweeted in response to the FT story that “the government has the wrong end of the stick” and that “the carbon footprint of sending an email is trivial.”

There are a number of places where the email-fretting analysis gets hung up. For one thing, even assuming all the numbers involved are accurate, the carbon impact adds up to less than one-tenth of one percent of the UK’s total emissions—hardly a worthwhile prize to exchange for creepy government email oversight.

And there are plenty of reasons to question the validity of the numbers, which Berners-Lee himself made clear were the product of decade-old, back-of-the-envelope guesstimates, not a recent, rigorous analysis. They first appeared in a 2010 book Berners-Lee wrote about carbon footprint accounting, and were primarily meant as an example of the small, subtle ways that our personal footprints can pile up.

Since then, a lot has changed. Information technology researchers have found that the energy efficiency of data centers doubles every two years, so any figures from 2010 would be far outdated. According to research in Science earlier this year, the world’s data centers use about as much energy as 18 million American homes per year. Sounds like a lot—but that’s only about 1% of global energy use. And it may be even lower: This week the International Energy Agency released updated estimates for global data center energy use that show double the efficiency of earlier estimates.

And while efficiency is increasing, the electric grid is also becoming cleaner, and data centers are only as dirty as the grid that runs them. In 2010, three-quarters of the UK’s electricity came from fossil fuels; this year, almost half came from renewable sources like wind and solar, with the ratio continuing to improve all the time.

What’s more, data centers (and our laptops, routers, and all the other electric gadgets required to send an email) are running regardless of how many emails we send. As a result, the marginal climate impact of sending one more email, or not, is essentially zero, said Jonathan Koomey, a former researcher at Stanford University’s School of Earth, Energy, & Environmental Sciences who now runs a California-based IT consultancy.

“For a lot of equipment in the IT system, there’s a fixed amount of energy to run it,” Koomey said. “The system is not energy proportional—doubling the IT load doesn’t double energy use.”

Even if it did, Koomey said, consider the bigger picture: If sending an email or making a Zoom video call allows you to avoid driving or flying to an in-person meeting, there’s a net carbon benefit. Besides, he said, if governments are really interested in decarbonizing the internet, there are more important policy targets than the number of emails people send.

The first would be to make it easier for data centers worldwide to procure renewable electricity. That could entail extending clean energy tax credits, strengthening regulations on power-sector CO2 emissions, and supporting local markets for renewable energy credit (REC) purchase agreements, a type of contract that data centers and other industrial customers can use to source clean power when it’s not practical to install on-site wind or solar. In the US, Apple and Google have reached 100% renewable power for their data centers through the use of RECs, and have been instrumental in lobbying to open REC markets in countries like Taiwan. Power companies themselves can also make better use of data and computing to operate more efficiently.

Climate change is a failure of the global economic system more than a collective failure of individual consumer choices. So if you’re worried about emissions, don’t sweat your email—instead, use it to stay informed and engaged. And the “cheers” you send someone could be worth the smile it elicits in this stressful year, even if it costs a minuscule puff of CO2—which, to be clear, it probably doesn’t.