The Carbon Footprint of Carbon Copies: How Does Email Affect the Environment?

With each passing year, the urgency and focus on our collective effect on the climate grows, and the statistics on how much time we have to turn the tide on this issue becomes increasingly alarming. As you likely know only too well, the UK is hosting the 26th UN Climate Change Conference of the Parties (known as COP26) currently and has no doubt got many of us thinking about how we can do our part.

While it can seem daunting to try and tackle these global problems at an individual level, there are thankfully many small ways in which we can help make a difference, and one such surprising way is your inbox.

In the time it’s taken you to read this, there’s a good chance that the spam folder of your inbox just received another useless email. Maybe it’s in your work inbox, or your personal inbox, or your other personal inbox, or your other other personal inbox, but that email is taking up digital space—and the electricity required to do so—all the same.

And while spam may be the most annoying perpetrator of unwanted waste in your email, the messages we actually compose and read ourselves add more to our carbon footprint than you may realize. SEDNA is on a mission to stop email overload, and have put together below the numbers behind excessive email culture, as well as some simple ways improving your email habits can benefit the planet as a whole.

How Do You Calculate the Carbon Footprint of an Email?

Understanding the environmental impact of an email starts with figuring out how to measure the greenhouse gas emissions created by one. When composing a message, your laptop or phone is using electricity. When you hit “Send” on the message, the network connection powering your Internet uses electricity, as does the server that transfers your message to its intended recipient. So, how do we measure the total carbon footprint of an email? For a general idea, you can use tools like the handy email CO2 calculator, but there are, of course, some more in-depth studies that have been conducted to help answer this question, including that of Lancaster University professor Michael Berners-Lee.

In Berners-Lee 2010 book “How Bad Are Bananas?” Using the metric CO2e (which represents the combined carbon dioxide equivalents from all forms of greenhouse gas the source generates), Berners-Lee calculates an estimated measure of the carbon contribution of everyday products and routine activities, including email use.

As a yardstick, Berners-Lee averages each person’s annual individual carbon footprint as being about 7 tonnes CO2e. To give you an idea of what that looks like, know that you would release one tonne of carbon by burning about 120 gallons of gasoline; that’s enough petrol to fill a living room aquarium.

Most people don’t think in fish tanks though, so translating CO2e sometimes takes more relatable comparisons. In late 2019, you may have seen headlines claiming staggering stats about the waste of “Thank You” emails alone—those one-to-two-word messages of gratitude that, unfortunately, still cause carbon. Energy supply company OVO caused a minor stir when estimating that each round of Thank You emails made by the adult population of the U.K. alone created the carbon equivalent of 81,152 flights from Heathrow to Madrid—that’s a lot of fish tanks!

But just as our understanding of the impact of emissions continues to evolve, so too do our methods of measuring that impact. That’s why Berners-Lee updated his findings last year with updated data. The result: a more accurate understanding of what our email footprint really looks like.

What Is the Carbon Footprint of Email?

With new data in hand, Berners-Lee estimates that an individual email can be anywhere from from 0.03g CO2e  to 26g CO2e. That wide range owes to the different ways in which emails are used, both by those with good intentions and those without.

When it comes to the latter, spam is the most benign offender, coming in at only 0.03g CO2e. But what about the sheer volume of spam being sent, which is exactly what makes it so annoying in the first place? Statista estimated more than 306 billion emails were sent by email users in 2020, with just under 50% of those being spam messages. If that balance shocks you, it’s probably because your inbox spam filters are doing their job, preventing unwanted spam from ever getting your attention. These unseen messages still use electricity as they travel, but spam only accounts for a negligible percentage of your inbox’s carbon footprint.

The reason? As it turns out, attention paid to each individual email is just as, if not more important than, the volume of email sent itself. That’s because the longer you spend composing, reading, or replying to a message, the more electricity you’re using. Even a short email that’s written and read efficiently produces 0.3g CO2e, 10 times the amount of a spam message.

Where the numbers really start ballooning are in mass-blast, long-winded, “this email could have been a text*” messages. Berners-Lee saves such examples for the upper range of his estimates, calculating that an email you spend 10 minutes writing, then send to 1 person who actually reads it, as well as 99 other people who scan and ignore the message, creates 26g CO2e. With 4 billion email users active globally, that 26g can add up quickly.

Is the Email Problem Getting Better ? 

While the world is getting more aware as to the environmental impact of email, it still seems that the road ahead may be rocky without some real change, and indeed, plenty of sources predict an increase in email if anything:

“the number of e-mails sent and received globally has increased each year since 2017. While roughly 306.4 billion e-mails were estimated to have been sent and received each day in 2020, this figure is expected to increase to over 376.4 billion daily mails by 2025.”

Statista, 2021

Not only is the use of traditional email platforms predicted to increase, further adding to the carbon footprint of each and every one of us, but it’s a practice that’s also becoming increasingly detrimental to how humans live and work together:

“Psychologist Dr Jo Lukins says email is the digital equivalent of clutter, “a constant uncontrollable source of information and tasks [that] can negatively impact our physiology and increase our stress levels”.

The Guardian, 2021

With email so heavily ingrained into our everyday lives, it’s little wonder that it’s having a critical effect on the planet, not to mention robbing us of our time and destroying the productivity of our businesses. 

So, Is My Inbox Killing the Planet?

The (mostly) good news is, no. By Berners-Lee’s accounting, even if every email sent required 4 minutes of combined reading and writing time, the total amount of carbon created annually would be 150 million tonnes globally, accounting for 0.3% of the world’s footprint. It’s a drop in the bucket compared to other contributors, and as an alternative to letter mail (which creates 20 times as much CO2e), email is generally an efficient means of sending written communications.

But like any new technology, increased efficiency runs the risk of creating more carbon through excessive, careless use. Even if the small but real contribution your inbox makes to your personal emission count doesn’t give you pause, the other waste created by an unmanageable inbox—lost time, wasted storage, annoying notifications— may. For your own sake, as well as the planet’s, consider adopting some of these useful tactics for improving your email hygiene:

  • Unsubscribe from mailing lists you don’t use

  • Keep your own mailing lists up-to-date

  • Write concisely

  • Only message those who need the information you’re sending

  • Avoid sharing your email address with potential sources of spam

Do some of these sound familiar? Many of these points are cornerstones of the iconic Inbox Zero method of handling email and can certainly make a dent when it comes to wrestling with the email problem, but is it enough to help the planet?

While there’s no silver bullet for the complex problem of our carbon footprint, there are small changes we can all make to help do our part. Whether that’s choosing to bike somewhere instead of driving, or making dietary adjustments, the associated benefits of lowering our carbon contributions can be reason enough to make a change, and why should that stop at email?

Here at SEDNA, reducing the volume of emails businesses receive and creating an intelligent communication system has been our bread and butter for quite some time. It’s on this basis that we’ve helped transform our customers’ organizations, and it’s also close to our hearts that in some small way, we’re also helping them diminish their carbon footprint too. After all, we’re all in this together, right?     

Want to reduce your own organization’s email volume as much as 95%? Book a free, personalized demo of SEDNA to see how.


*0.8 g CO2e for a single text message, according to “How Bad are Bananas?” 2020