Which is more sustainable: SMS, instant message or email

Worldwide, mobile messaging usage is growing at a higher rate than any other mobile app. WhatsApp is the most popular messaging app in the world, with over 2 billion users. About 500 million people worldwide have a Telegram account. A survey by mobile data and analytics company App Annie, conducted this year, found that the average global time spent on mobile apps was 4.2 hours per day.

Worldwide, an estimated 294 billion emails were sent and received daily from 3.7 billion users last year alone.

All of these communications mean that there are a lot of data flows going on. Yes, data streams consume energy and therefore release CO2. So, from an environmental point of view, it is interesting to know which is the most sustainable option. Should we use SMS, an instant message through an app or send an email?

Different technologies, different impacts

You must be thinking that the impacts of messages have to do with the type of smartphone, right? So-so. The device needs electricity to work and send a message. But the energy required to manage, transport and store this data is what counts most.

An SMS, an IM or an email do not share the same environmental impact because they do not use the same technologies. While SMS uses conventional telephony frequencies, instant messages and emails use data streams from the Internet. These are different ways of processing data that use different amounts of energy.

A simple average email emits 4g of CO2. One SMS, 0.014g – these are some of the calculations that Mike Berners-Lee, one of the greatest sustainability researchers, wrote in his book How Bad Are Bananas? The work talks about the carbon footprint of various products. Among other variables, the author used data from cell towers, data transfers and data centers for his accounts.

Data provided by the multinational mobile operator Vodafone, an SMS with a maximum weight of 140 bytes emits 0.00215g of CO2 – less than an email.

Regarding instant messaging, there is still no concrete data to predict its carbon footprint. However, as these communications use internet networks, it is reasonable to think that their carbon footprint is closer to an email.

Yes, we can say that using SMS is more sustainable than using instant messages or emails. But a message with more than 160 characters would increase the energy spent and then that count changes as, by adding extra megabytes, we increase the carbon footprint. Remember that the more data to be processed, the more energy is needed?

It is estimated that the worldwide exchange of text messages emits 32,000 tons of CO2 a year, which is very little compared to humanity's total footprint: 40 billion tons in the same period. In other words, it is much more urgent to revisit other habits. Anyway, when we think about the environment, everything matters. In this case, if you want to act in the most sustainable way, it is best to go back to the good old SMS from years ago. Preferably without attachments.