The carbon footprint of email

In 2013, Google released one of their biggest updates to Gmail—the segregation of the inbox into Primary, Social, and Promotions tabs. Inbox feeds were, almost magically, cleaned up. Every time you opened your inbox after the update, you were presented with important mails—ones you actually needed to read—only, with all the noise relegated to secondary tabs.

It’s easy to ignore emails in the Social and Promotional tabs. And with Gmail’s generous 15GB storage allowance, you never really need to worry about them piling up. Except, it turns out, you do.

Emails, like most things, have a carbon footprint. And considering the world sent and received nearly 300 billion of them in 2019, that carbon footprint can add up to quite a bit. In his book, How Bad are Bananas: The Carbon Footprint of Everything, Mike Berners-Lee, a professor in the environment centre at Lancaster University, estimates that an average spam mail has a footprint equivalent to 0.3g of CO2 emissions, a standard email 4g of CO2 emissions, and an email with “long and tiresome attachments” 50g of CO2 emissions.

The average office employee receives 120-180 emails per day. If one were to assume that 50 percent of these are spam mail, 25 percent standard emails, and 25 percent emails with attachments, that would create a daily carbon footprint equivalent to 1638g of CO2 emissions at the lower end of that estimate. Annually, that adds up to nearly 0.6 tonnes. That’s the equivalent of driving 4000 kilometres in a car.

Why does email have such a heavy carbon footprint? Composing an email on your device consumes electricity, and so does opening and reading it. Behind this simple transaction, however, lies a complex global web of computing and internet infrastructure. Emails are transmitted through and stored in massive data centers, which consume copious amounts of power. Berners-Lee estimates that data centers around the world will produce anywhere between 250 and 340 million tonnes of CO2 equivalent emissions in 2020. Instant messaging platforms such as Whatsapp too have a carbon footprint that is nearly as heavy, since they use much the same infrastructure to transmit text and media.

Luckily, reducing the carbon footprint of your inbox is relatively easy. Open the Pandora’s Box that is your Promotions tab and unsubscribe from all those marketing emails you will probably never open. Change your social media account’s communication preferences to stop receiving notification emails. Stop marking entire teams as CCs on work mails and stop sending “Thank You” replies. Ensure that your emails contain all the relevant information the first time around so as to obviate the need for follow-up mails. Delete your years of archives of daily newsletters. And finally, where possible, link to files or information online instead of sending them as attachments.

Cleaning your inbox is every bit as satisfying as cleaning your wardrobe, desk, or room. And a lot easier to boot.