Understanding the carbon footprint of our emails

Updated: Sep 25, 2020

Little by little, we are becoming aware of the environmental impact of our electronic equipment, as well as the constant impact of the use we make of it.Indeed, the carbon footprint of the internet (emails, streaming...) is growing every year and is becoming a real problem that needs to be addressed today. Let's start by understanding the impact of our emails.

Computer and digital footprint of our devices. The hidden footprint of our digital uses and habits. Carbon footprint of emails, computer, phones. Global Warming. Climate Coping.
Digital footprint

TLDR: The numbers are still widely disputed, but recent studies suggest that the carbon footprint of emails is lower than previously thought, and would reach around 0.4 g of CO2eq.

What happens behind our emails

To understand what happens when you send an email, we have to break down the whole process behind it. There are different actors involved in this matter:

  1. A sender (you for example) uses an online messaging service to write an email.

  2. The sender data center (servers) of this messaging service processes the sending request and store the message in the sender letterbox (as well as the attachment if there is one).

  3. The receiving data center the processes the reception of the email and store it in the receiver's letterbox (you guessed it, with the attachment).

  4. The receiver (your friend or colleague for example) finally receives the message and store it locally.

  5. And to connect all this, there is the Internet network: a gigantic mesh of equipment (cabling, routers, etc).

Once the email has been received, it will remain on the transmitting and receiving data centers, sometimes for a very long time (decades).

Infographics. How do emails work. The path of an email from the sender to the recipient through the DNS servers. Global Warming. Climate Coping.
The Email System, by Mocomi

Let's dive in!

Sending an email and storing it are the two things that can have an impact in terms of greenhouse gas emissions. But then, how much are we talking about?

On average, sending an email with a 1 Mb (megabyte) attachment would be responsible for emitting 20 g of CO2 equivalent (CO2eq). This is still a pessimistic scenario though as 1 Mb is already quite big for an email (well depends on your line of work). So if we were to apply that to our lives, we would reach numbers such as:

  • Sending an email with an attachment would be equivalent to keeping a light bulb on for an hour.

  • The emails of a company of 100 people would emit 18 tonnes of greenhouse gases every year, the equivalent of 18 return trips from Paris to New York and back.

However, these numbers are still widely disputed, ad more recent studies reached a much lower amount of 0.4 g of CO2eq, i.e. 50 times less. So, to date, we don't really know what the right figure is, but everyone agrees that it is lower than the initially thought figure. On the plus side, these revised numbers make emails a smaller threat to environment than most things we consume everyday such as fossil fuel, food, etc. With the figure of 0.4 g of CO2eq, despite the incredible number of emails sent per day around the world (293 billion, excluding spam!), they would only represent 3% of the impact of digital technology. Watching videos, for example, has much more impact.

Infographics. The carbon footprint of a letter made from recycled paper from reception to recycling. The carbon footprint of a standard email in normal length with no attachement. The carbon footprint of a text message. Global Warming. Climate Coping.
Another view on carbon footprint, by Esendex

The manufacture of user equipment is responsible for 90% of the impact of an email stored for 15 years

The electricity needed to run the data centers around the clock is not the main problem. Although they are always on, a lot of effort is made to optimize their electricity consumption (and therefore their cost!). This has borne fruit with significant progress made in recent years. The reason why manufacturing equipment is so expensive is because the cost of extracting metals, refining them with a lot of chemicals or transforming them into electronic components is very energy-intensive and environmentally destructive. Added to this are serious environmental and health problems related to water pollution, as well as tensions over the acquisition of "conflict minerals" such as coltan and gold.

Infographics. Comics. Understand carbon footprint of emails and how to reduce your digital carbon footprint. Global Warming. Climate Coping.
A fun and nice summary, by Tonecreative

Tips to reduce your emails' impact

So, as we discussed it, the main impact of an email is due to the cost of manufacturing user equipment. In order to downplay your impact on the environment, the best advice we can give you is to extend the life span of your equipment.

Then, to limit the impact during emails shipping, you can try to develop the following good digital habits:

  • Think carefully about the necessity of sending an email.

  • Add only the relevant recipients.

  • For the attachment, prefer an online storage platform to avoid storing it in multiple locations. Even better: use platforms like WeTransfer where the storage time is limited in time.

  • When forwarding an email, remove the recipients that are not relevant, delete the attachment if it is not needed.

  • Avoid heavy signatures, especially with images.

  • When you receive a newsletter, ask yourself: "Is it really useful?". If not, go to the bottom of the email and unsubscribe. Although it may not be very effective in the fight against global warming, it will always leave you with fewer emails to read.

Of course, emails are only a drop in the bucket. However, as is often the case, these thoughts invite us to be more sober and to think carefully about how we use them. A good email is a useful email.

Infographics. 9 tricks to reduce the digital carbon footprint in an ecology movement. Global Warming. Climate Coping.
Reduce your digital footprint with these 9 tips, by Digital for the planet

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- Tips and tricks to reduce your digital carbon footprint on a daily basis

- Are renewable energies really that clean?

- Another look at plastics: the German deposit system