The footprint of an email comes from the electricity needed to power the equipment used at each stage of the process

The next time you write a quick “thank you” note in an email, think twice before pressing the ‘send’ key. According to energy supplier OVO’s “Think before you thank” campaign, changing that habit across the UK population would equate to taking 3,334 diesel cars off the road for an entire year.

Every 18 seconds

Our demand for internet and smart technologies is increasing rapidly, and by 2025, every person in the developed world will have at least one ‘interaction’ with a data centre every 18 seconds of their lives. In 2023, the world’s 4.4 billion email users are predicted to send 347.3 billion emails each day.

But that demand brings with it an additional strain on the power grid. And the statistics and forecasts make for sobering reading. Data centres are major energy users, with some of the largest consuming more electricity than several entire countries put together.

In fact, the International Energy Agency estimates that 1% of all global electricity is used by data centres, and that by 2025, they will consume some 20% of the world’s power supply.

On a more positive note, though, while average energy use is increasing steadily, the data centres are becoming more and more efficient. They are actually consuming energy at a rate only little higher than they did 20 years ago, thanks to advances made in cloud storage facilities (often called hyperscale centres) and in other areas.

The impact of email

So, what can we do about it? Perhaps the best place to start is by getting a good idea of our own carbon footprint. Calculating it isn’t an exact science, but numerous attempts have been made over many years to provide some kind of measurement.

Mike Berners-Lee is a researcher at Lancaster University in the UK, author of the book The Carbon Footprint of Everything and founder of Small World Consulting, a company that researches the carbon footprints of the general public. He estimates that the “cost” of a short email from one laptop to another is some 0.4g CO²e, while a longer one that takes 10 minutes to write and 3 minutes to read, sent laptop to laptop, weighs in at around 17g CO²e. One with a large attachment can reach up to 50g.

The book also reveals that the footprint of an email comes from the electricity needed to power the equipment used at each stage of the process: the device it is written on, the network that sends it, the data centre it is stored on, and the device it is read on. It’s the devices at each end that are the key factors, even when large attachments are being sent.

Streaming compared to car driving

Is streaming movies and music your thing? Rabih Bashroush, a scientist at the EU-funded Eureca project, worked out that the five billion streams of a music video from 2017 used up as much electricity as the entire countries of Chad, Guinea-Bissau, Somalia, Sierra Leone, and the Central African Republic put together in a single year.

"Could video streaming be as bad for the environment as driving a car?", asked physics professor Stefano Bonetti recently on the commentary website The Conversation. Since he is a physics professor, he calculated the energy use and concluded that streaming a two-hour movie on a normal phone or computer is comparable to the emissions from a 45-minute car drive. This is quite mind-boggling for something that we perceive as immaterial.

This text is an excerpt from article “Cleaning up the planet, one footprint at a time”, written by Geoff Mortimore, featured in PAPER #5.