Calculating the pollution effect of data

There are many ways that digital can create pollution. Let’s start by looking at how much data we use and what pollution it causes.

Analysis by Cisco indicates that an average US citizen is using 140 gigabytes (GB) of data a month. What sort of pollution is that causing? That’s not an easy question to answer. If you search for information about data energy usage, then you’re likely to find studies that state that transmitting and storing one gigabyte of data consumes 7 kilowatt hours (kWh), or 3.9 kWh or 0.06 kWh: a huge variance. You will find that the 7 kWh figure is quoted quite a bit, but if you dig deeper you will find that the study this figure is based on was published in 2009, and that networks have become much more energy efficient since then.

Here lies a data integrity problem. Not much gets archived or deleted on the Web. Wrong and out-of-date information is everywhere. Older content often comes up earlier in search results than fresher, more recently published content. As Norbert Wiener stated in 1950, “The idea that information can be stored in a changing world without an overwhelming depreciation in its value is false.” As the Web gets older, more and more of it becomes “fake” because the information it seeks to communicate is no longer accurate. You have to do your homework if you want to get close to the facts.

Turns out that the 0.06 kWh is a figure published in 2015 that was based on a review of multiple other studies and seems to be the more accurate one. According to this analysis, the amount of energy required to transmit and store data has been decreasing by half every two years since 2000. Extrapolating that trend outwards, we get a figure of 0.015 kWh per GB, and that is the figure I will use in my upcoming book, World Wide Waste.

The next step is to estimate how much CO2 is created per kWh. According to UK government figures published in 2018, the amount of CO2 created per kWh is 0.28 kg. Thus:
0.28*0.015 = 0.0042 kg of CO2 for every GB streamed/transmitted.

Interestingly, a widely discussed article published in February 2020 by George Kamiya, of the International Energy Agency (IAE), had a seven times higher figure. It estimated 0.06 kWh/GB and 0.478 kg CO2/kWh, which would result in 0.028 kg of CO2 per GB streamed. For various reasons, we are happy to stick with our much more conservative number, because even under very conservative conditions, digital pollution is substantial and growing at a frenetic pace.

According to Cisco, in the United States Internet traffic will grow 3.1-fold from 2017 to 2022, an annual growth rate of 25%. Average traffic per person per month will grow from 120.2 GB in 2017 to 304.6 GB in 2022. For World Wide Waste, I used a figure of 140 GB per month.

A monthly data usage of 140 GB per US citizen comes to 2.1 kWh or about 0.59 kg of pollution. The population of the US is 327 million. So, every year US citizens’ data production and consumption habits emit about 2.4 billion kg of CO2. You’d need to plant 230 million trees to deal with that pollution. (An average tree can absorb 10 kg of CO2 per year.) By 2022, Cisco estimates it will be 304 GB per person per month. We’d need to plant over 500 million trees to deal with that.

Electricity Intensity of Internet Data Transmission, J. Aslan, K. Mayers, J. Koomey, C. France, Journal of Industrial Ecology, 2015

Greenhouse gas reporting: conversion factors 2018, GOV.UK

What is the carbon footprint of streaming video on Netflix? George Kamiya, International Energy Agency in Paris

Cisco digital forecasts 2017–2022, Cisco