What's the carbon footprint of ... email?

I’d never thought about the impact of spam messages on the environment, and the “rebound effect” that occurs when a low-carbon technology results in higher-carbon living simply because we use it more. From today’s Guardian.

techspotlight:

Our recent piece on the carbon footprint of the internet generated plenty of coverage, so next up in our map of the world’s carbon emissions is … email.

Of course, sending and receiving electronic message is never going to constitute the largest part of our carbon footprints. But the energy required to support our increasingly heaving and numerous inboxes does add up.

Very roughly speaking (remember that all complex carbon footprints are really best guesses), a typical year of incoming mail for a business user – including sending, filtering and reading – creates a carbon footprint of around 135kg. That’s over 1% of of a relatively green 10-tonne lifestyle and equivalent to driving 200 miles in an average car.

According to research by McAfee, a remarkable 78% of all incoming emails are spam. Around 62 trillion spam messages are sent every year, requiring the use of 33bn kilowatt hours (KWh) of electricity and causing around 20 million tonnes of CO2e per year.

McAfee estimated that around 80% of this electricity is consumed by the reading and deleting of spam and the searching through spam folders to dig out genuine emails that ended up there by accident. Spam filters themselves account for 16%.

The actual generation and sending of the spam is a very small proportion of the footprint. Although 78% of incoming emails sent are spam, these messages account for just 22% of the total footprint of a typical email account because, although they are a pain, you deal with them quickly. Most of them you never even see. A genuine email has a bigger carbon footprint, simply because it takes time to deal with.