Every page on the Internet emits CO2

First published on Norma.

“Please consider the environment before printing this email” is an invitation used to be found written in green at the bottom of email messages. It exists in various forms, but the original one may come from thinkbeforeprinting.org (1).

The message is actually harmless, suggesting to avoid wasting paper (and especially ink) to print an email. However it also feeds the false belief that everything that is digital is totally virtual and has no corresponding impact in the real world.

Transferring 1GB of data on the Internet results in an emission of carbon dioxide between 2 and 3 kilograms. No precise data is available, but estimates like the one made by Emerge (2) or another one published on Energuide (3) are available. Although the estimates may be exaggerated, the Internet does indeed have a huge energy cost, and since only a few of the servers currently on the network are powered by renewable energy, this cost has an impact on the amount of carbon in the air.

The e-mail signature mentioned above, as a green .gif image, weighs about 3KB. It would take a thousand emails to reach 2 grams of CO2: definitely irrelevant if it wasn't that 280 billion emails are sent every day (4). If each one of those contained that innocuous environmental message as an image, 550 thousand kilos of carbon dioxide would be roughly consumed daily. In comparison, at least the paper can be recycled.

Discount messages for Black Friday and Cyber Monday account for one the highest volumes of emails sent. Often accompanied by heavy images, these messages often end up in the trash bin.

If three kilobytes of information can have such a strong energy impact, we must now weigh the websites to the same extent. A single Internet page weighs an average of 3MB today (5), a number almost quadrupled in the last 10 years. Do we have much better content today than in 2008 to justify its energy abuse? Sometimes yes, but the bulimia of irrelevant images published on social networks doesn’t help.

Videos, images, advertisements and complex pages use precious electricity at the source, during the transfer and at the final computer. Rationalizing the use of the network is up to the designer as much as the user.

Each article on this website usually weighs less than 450KB, which is even less than the average of pages 10 years ago. The point is that this article contains information, be it useful or not, and nothing else — to limit energy waste as much as possible. It would therefore require an act of responsibility to avoid designing websites with heavy background images or other CPU-intensive scripts that won’t add any content, because the weight of the choices isn’t just virtual.

(1) Think before printing: Put the message in your message! [thinkbeforeprinting.org]

(2) Julian Pscheid, "Does Irresponsible Web Development Contribute to Global Warming?" Examining the Impact of Bandwidth Usage on Greenhouse Gas Emissions [emergeinteractive.com]

(3) Do I emit CO2 when I surf the internet? [energuide.be]

(4) Heinz Tschabitscher, "How Many People Use Email Worldwide?" [lifewire.com]

(5) The average web page is 3MB. How much should we care? [speedcurve.com]