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The carbon footprint of data (& why I quit AT&T Wi-Fi)

I quit my home Wi-Fi service from AT&T and am completely happy with that decision. I was paying $55 a month for very slow Wi-Fi service (about 5 Mbps, megabits per second) and now I simply use my phone as a mobile hotspot – it’s cheaper, requires no additional hardware, and is actually much faster than my old Wi-Fi. There are several reasons why quitting home Wi-Fi made sense for me:

  1. It reduces the amount of electronic hardware in my home
  2. It encourages me to use my time more productively
  3. It simplifies my life, reducing expenses and my carbon footprint
  4. I feel better having severed a contract with a company that does very little for me

Here’s some more detail on why I quit AT&T.

AT&T Fiber upgrade?

I’ve gone through what’s probably typical evolution of home internet service. Initially, I had a phone landline which also carried my (DSL) internet signal. A decade ago, I got rid of the landline and switched to cable-based internet, using cable that was already connected to the apartment. Over the summer of 2021, AT&T started making it known (mostly via annoying junk mail) that they were more or less discontinuing cable-based internet. I called to check if I could just continue my existing service and was told that everyone needs to upgrade to fiber. Here’s a description of DSL, cable and fiber in case it’s of interest.

Why didn’t I just upgrade like everyone else? Well, for the reasons outlined above, but it was also triggered by becoming fed up with AT&T’s customer service. Here’s a brief summary of my departure from AT&T:

  1. Customer service tells me that I will basically have to upgrade, sooner or later.
  2. An AT&T agent literally laughs when I tell her my current internet speed (5 Mbps) – she’s basically mocking me for the crappy service that I’m receiving from her own company!
  3. When I tell her that I’m ready to quit I had to be transferred to a specialist – that is, a guy whose job it is to intimidate people into not quitting. Once he figured out that I had no intention of changing my mind, he bizarrely switched tactics to being ice cold with me. Perhaps it was the last-resort tactic outlined in his script. I asked him if I could return the Wi-Fi router to AT&T for recycling and he told me to trash it – AT&T doesn’t want it or particularly care what I do with it. So much for, “Thank you for being a customer for two decades!”

I have to say that it felt good to sever that contract. I don’t dislike AT&T as much as Comcast /Xfinity (which I cut the cord from years ago) but I certainly don’t love the company.

Hardware required for AT&T fiber service

If upgrading to AT&T fiber was straightforward, I probably wouldn’t have had such a big issue with it. But the installation of fiber internet involves quite a lot of hardware:

Here’s a video showing this equipment

Don’t get me wrong: Fiber is overall a more sustainable choice for connecting new homes to the internet (and for servers, data centers, etc.). In my case, I already have a wired connection and switching would involve the installation of a lot of new equipment. Given our situation with plastic pollution and many the social and environmental issues of the electronics industry, I figured I would skip all of that and try out the alternative – relying solely on my phone.

In the meantime, my mission was to figure out the actual carbon footprint of that data because the estimates that I found online varied wildly.

The carbon cost of internet data

Quitting AT&T is not just about saying no to the equipment or to the company that clearly doesn’t care about me (or recycling their old equipment, for that matter). It’s about being conscious about the amount of data that I use. As mentioned in a post on Amazon ethics and social responsibility, the information technology and communications (ICT) sector now has a significantly larger carbon footprint than air travel. The sector accounts for more than 3.7% of global CO2 emissions, eclipsing the carbon footprints of most individual countries.

The efficiency of data transfer increases over time but the rate of data use is growing at a larger pace. In an age when everyone is focused on reducing carbon footprints, the energy demand for data is increasing at an alarming rate. Some companies (e.g., Google, Apple) have made good progress towards adopting renewable energy while others (e.g., Amazon, which powers a lot of the web) has not lived up to its promises.

A projection of the electricity demand by the ICT sector (Anders Andrae, Nature, 2018). The sector is projected to use around 20% of global electricity by 2030, with the largest growth in demand coming from networks and data centers.

Let’s take a look at the carbon footprint per gigabyte (GB) of data.

What’s the carbon cost of 1 GB of data?

Calculating the carbon footprint of internet data is not straightforward. That’s partly because it’s a fluid situation – data transfer efficiency increases over time and there’s also a big difference in renewable energy use across networks. Some analysis has got it badly wrong, and I’d recommend reading this article from the International Energy Agency (IEA), correcting assumptions about the carbon cost of watching Netflix.

From the IEA article, the electricity cost for transferring 1 GB of data over 4G mobile (in 2019) was around 0.1-0.2 kWh. 2020 estimates for data transfer range from 0.025-0.23 kWh/GB – a fairly wide spread. If we take the mid-point of this range, we have an average electricity cost of 0.1275 kWh /GB (which roughly match with projections made here). The IEA estimates the average carbon cost of electricity in the US at 0.42 kg of CO2 emissions per kWh. So, multiplying those together, the average carbon cost for transferring 1 GB of data is around 0.054 kg (54 grams) of CO2.  

The carbon footprint of data, per person (US)

Note that estimates for the carbon cost of transmitting data vary widely, mainly due to uncertainty about the electricity cost. This guy, estimates the cost at 0.0042 kg of CO2 for every GB, while this article claims that it’s 700 times higher than that at 3 kg per GB.

In 2022, Americans are expected to use around 3,650 GB of data per person per year, so going by those two estimates, that carbon footprint would ranges from 15 kg to 11 tonnes per person! Clearly the higher number is incorrect and those calculations have been shown to be flawed. I think the low estimate is too low and that the correct number is closer to 200 kg CO2 per person (based on 0.054 kg per GB).

What’s the carbon footprint of my phone plan?

My personal data carbon footprint, with my 35 GB per month phone plan, is around 1.9 kg CO2 per month, or 22.7 kg CO2 per year (using my estimate of 0.054 kg of CO2per GB) That’s not a huge amount, but bear in mind that I’m on a fairly strict “data diet” – it requires some effort to stay within that 35 GB/month limit. Streaming video on TV for an hour will bring me close to the 1 GB daily limit.

It would be incredibly easy to blow past my monthly data diet. The data cost of streaming Netflix ranges from 0.25 GB/hr for mobile to 0.7 GB/hr for standard definition (SD) and a hefty 7 GB/hr for ultra-high definition (UHD/4K). So that’s a big difference – I can watch an hour of SD Netflix (or 4 hours on mobile) and stay within my daily data budget but I’d use up a month’s worth of data with just five hours of 4K video!

Yes, limiting myself to 35 GB per month is a challenge but….

A data diet is good for mental health!

Don’t I want to watch 4K Netflix on an 86” 4K TV for 5 hours every night? I kind of do, sometimes, but I also very much don’t.  Don’t get me wrong – since going on this data diet I do stream a lot less video, but I do borrow movies and TV shows from my wonderful local library. Support your local libraries folks – they are not guaranteed to stick around. For example, the UK has closed one fifth of its libraries since 2010.

Despite the AT&T and Xfinity ads insisting that happy families are all online all the time (multitasking with TVs, phones, and iPads as if they were day traders), I don’t want my life to be like that. Don’t get me wrong – I love the internet and do “need” internet service. I just don’t need gigabit speeds right now.

One of The Minimalists reported on the benefits of quitting home Wi-Fi, including having more time and less stress. I’m not at all ready to say goodbye to home Wi-Fi – I’m just using a different version of it and capping my usage. But I agree that it’s a good idea to think about the internet as a privilege and a limited resource, rather than to take it for granted.

Paying a flat rate for gigabit Wi-Fi pretty much encourages people to use tons of data – and that’s not a good thing.

Is internet data a significant proportion of my total carbon footprint?

The carbon footprint of my 35 GB per month data plan (22.7 kg CO2 per year) is pretty insignificant compared to my total carbon footprint, which I recently calculated using the CoolClimate model – roughly 7000 kg (7 tonnes) of CO2 per year.

However, let’s say I was watching five hours of 4K video per day (35 GB of data) – that would translate into a carbon footprint of 700 kg CO2 per year, about 10% of my total footprint. Not insignificant, especially since we should be aiming to reduce our personal carbon footprints to 2 tonnes (2000 kg) per year. 

Bear in mind that the carbon cost of running devices needs to be added to the carbon footprint of streaming the video. A large TV requires around 200 watts of electricity. I’ve gone through calculating the carbon footprint of home appliances before, but here it is again. Watching a 75” TV (200 watts) for 5 hours per day would consume 365 kWh of electricity. If we assume the same carbon cost as before (0.42 kg of CO2 emissions per kWh) then that TV’s footprint is around 153 kg CO2 per year. For most homes, a TV is the largest energy expense after heating and cooling (central heating, water heater, air conditioner, fridge).


That was a rambling post so I’ll summarize my thoughts, together with a few final factoids:

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