What is the website carbon footprint?
AuthorJustyna Weronika Łabądź
At first, it may sound shocking and unbelievable, or even weird and funny to others, but it's true: A website can produce CO2 and increase environmental pollution. How? Let's dive into this topic.
Table of contents:
The weight and the cost of digital
The internet can be an attractive and valuable space; some people can treat it even as an alter and more important reality. It helps us get information quickly, work effectively, and communicate with people beyond distance and borders. Without a doubt, it has changed the world in so many ways. But just like any other part of life, it has its downsides, such as carbon emissions.
We got used to treating digitality as immaterial, invisible, with no body, so not weighted at all. But to be accurate:
Digital is physical. Every byte is supported by an atom. Every single action in digital costs the Earth energy. Turn the electricity off and you turn digital off. Digital is demanding an increasing share of the Earth’s energy and resources and is a major contributor to the generation of toxic trash (...)
The internet might be a virtual place, but it still has a real-world impact on the planet.
So how is it possible that every web has its carbon footprint and generates greenhouse gases? It's not as we would imagine, though. Computers, monitors, and other devices don’t have pipes releasing toxic gases that escape into the atmosphere and cause climate change. Internet carbon emissions come more from data centers, but sometimes we don’t realize its impact on a global scale.
The IT sector and the internet need an appropriate amount of energy to achieve its goals and serve its services and goods. And it’s not a small number. Researchers calculate that right now, the need for digital data costs us about 416.2 terawatts per year - that's the amount of electricity used during a year by the entire United Kingdom.
It is estimated by Internet Health Report 2018 that in 2025 the entire internet will emit more CO2 than any country except the U.S, China, and India.
The IT industry, through its consumption of electricity today, contributes to about 4 percent of all global greenhouse gases: even twice more than the aviation industry. What can make us worried is the prognosis that those values will change rapidly.
In the Cisco Annual Internet Report, the company predicts that in 2023 two-thirds of the world population will be connected to the internet. That means there will be about 5.3 billion total Internet users (66 percent of the global population) hungry for data and, unfortunately, generating a staggering amount of CO2 emission while surfing the web and using electricity.
Predictions go even further - Lotfi Belkhir and Ahmed Elmeligi, authors of the paper published in “Journal of Cleaner Production” in 2018, estimated that in 2040 communication technologies will consume 14% of the global energy, so about 10% more than in 2020.
And in all this hunger for more data, more users, and a need for the fastest and most engaging digital experience, we will have to think about how to make this unstoppable growth environmentally friendly and achieve net-zero emissions in the IT sector.
Firstly, let’s check what we exactly mean when we say that websites generate CO2e*.
* * * * *
*CO2e - stands for “Carbon dioxide equivalent” and it describes different greenhouse gases in a common unit: carbon dioxide (CO2), methane (CH4), nitrous oxide(N2O), Hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), nitrogen trifluoride (NF3). In articles on this website, we use the term CO2 instead of CO2e to make the content less confusing and easier to understand for a general audience.
* * * * *
How do websites produce CO2?
CO2 is a gas that is released when fossil fuels are burned. It's also created when electricity is generated by burning fossil fuels and when certain chemicals are made or used.
Digitality equals electricity. Without it, there is no internet, and we can't turn on the computer, router, TV, or charge any electronic devices. Data centers don't work without electricity. The IT sector's existence depends on energy even when it seems to produce immaterial sources and services.
So, from the web perspective, CO2 is emitted not only when we turn on devices that we need to surf the web. Every email, post published on social media, video watched, and article read cost us energy – it generates CO2.
The most critical factors in generating greenhouse gases in the IT sector:
- Data transfer
This is the most significant contributor to internet-related CO2 emissions and accounts for between 30% and 50%. Data is everywhere! The internet is data. Every day, users and web owners create over 2.5 quintillion bytes of data. By 2020, it was estimated that 1.7MB of data was created every second for every person on earth. That’s a lot!
According to estimation, while transferring the 1GB of data, we produce 3kg of CO2. The amount of it is equivalent to driving 7 miles (11.2654 km) in a car, so when you multiply that by billions of people around the world, it quickly adds up.
In 2018, 33 zettabytes* of data were created. By 2025, it’s estimated that there will be 175 zettabytes, and that by 2035 there will be more than 2,000 zettabytes, according to Statista.
*Zettabytes is a trillion gigabytes, so thousand billions of gigabytes.
Of course, the most polluting web activity is streaming videos. For example, one hour of streaming videos on Netflix in 2020 emits about 100g of CO2.
We produce CO2 as internet users when we:
- transfer data
- download data
- upload data
Activities such as emails, video watching, playing games, listening to music, writing articles, meeting online with clients, or reading news can generate CO2. That means that navigating and surfing through websites is also connected to data transfer, so it has its carbon footprint.
The weight of the web
One of the most significant impacts of carbon emissions on the web is its weight - so how much data it contains. We can calculate their carbon footprint by considering some factors, which we write below, in the section “How can we measure the website's carbon footprint?”.
Usually, we are unaware of how much the website weighs, let alone how much CO2 it generates. At Dodonut, we achieved 0,04g of CO2 for the homepage. As an aware brand promoting a sustainable web design and development approach, we proudly share our results in the web footer. Many other mindful companies do the same on their websites. Why are we proud of these results? Some would say that there is nothing to be proud of regarding CO2 emission, but when we compare it to an average website, I think we can say we are doing our best.
The average web page tested produces approximately 0.5 grams CO2 per page view. For a website with 10,000 monthly page views, that's 60 kg CO2 per year.
Website Carbon Calculator
However it is estimated that an average website can emit even more CO2! But, if we would like to compare values from Website Carbon Calculator, 60 kg is the weight of one average adult orangutan or more than the average weight of four Dodo birds! (if they would luckily still exist…)
And we should admit that an average page view per session for a website is around 2.6 pages per visit, so to be accurate, we should multiply the results by this number.
How about other data that shows that on the internet, there are over 2 billion websites, and 200 million of them are actively used?
The internet is getting obese. It greedily devours and generates more data, becoming an increasingly heavier colossus. The median size of a web page has grown by 30 percent from 2017 to 2020. Does it mean that they are better? Not really. Usually, they represent fancy, intriguing carousels, overcrowded visual forms with badly optimized files and images, and poor user experiences that may look appealing but are slow, overweight, and not accessible at all. Designing and developing with sustainability in mind and web efficiency could help overcome this trend of increasing the weight of web pages and the web carbon emission.
Data transfer is the factor that can be changed with two or even more sides. Firstly, the owners and creators of the websites can look for a more sustainable solution in their development and hosting. On the other hand, users can also be aware of their impact while surfing the internet, clicking or tapping on the next image, playing another video, and sending and receiving emails.
- Hosting and data centers
Data centers store information before it's sent to devices so that users can access it quickly. These centers require lots of energy and infrastructure, which causes them to emit CO2.
Due to the exponential increase in data traffic, data centers have become one of the fastest-growing sources of electricity demand globally. Although much of the world's energy is still produced by burning fossil fuels, they also are the biggest challenge in reducing carbon emissions.
Data centers are unavoidable. Every company, from big giants such as Facebook or Google to small companies that run their websites, needs a server on the internet that pulls energy from the electricity grid 24 hours per day, 365 days a year. Their need for electricity run primarily on fossil fuels causes enormous amounts of CO2.
This is important because according to a 2013 post in the New York Times, digital warehouses use about 30 billions watts of electricity, about the same output as 30 nuclear power plants. A single data center can use as much electricity as a small town.
According to the same article by James Glanz in the New York Times, Tim Frick quoted next estimations that data centers use 6 to 12% of the total electricity to power their servers. The rest is mainly used to cool servers down, keep them inactive, and guard them against overvoltages. That means that data centers can more or less waste 90% of used electricity.
And still, only a tiny percentage of them use renewable energy. Individual users don’t have an impact on it, sometimes even unaware of what kind of energy is used to power the server. However, this is the point for conscious designers, developers, and web and app owners that can choose if their product will run on green hosting and, this way, green, renewable energy.
- Devices, cables, batteries, and… new devices
Devices themselves also consume a lot of electricity when they're in use because they need batteries to run and cables to connect them to the internet. The vision when we connect to the internet through our brain so far stays in the area of science-fiction movies. Till now, we need some electronic devices to visit websites, download and upload data, send emails, and watch streaming videos. And nowadays, there are so many devices to do it: not only PC, laptops, tablets, smartphones, and ebook readers, but also Smart-TVs, smart fridges, and smartwatches.
Every time you connect your device to the internet, it uses data and is empowered by energy, which is the cause of CO2. Even if it runs on the previously charged battery, somehow, it has to accumulate the energy. The amount of energy also depends on how many devices we have connected, which means that we generate more CO2 when the computer is connected to a monitor, printer, keyboard, or smartphone to Bluetooth headphones.
Different devices will need different amounts of electricity to work and transfer data. Old devices can also emit more energy than newer ones; this means they're responsible for emitting even more CO2 than newer devices.
But not only this has an impact on greenhouse gases emission. Finally, they also had to be manufactured somehow, and all of their parts: cables, batteries, and their production emitted appropriate amounts of CO2.
The critical factor here is our consumption behavior. Do we need a new laptop or smartphone, while the old one still works correctly? According to the research, the natural lifecycle of the laptop and its use is 3 years for businesses and 5 years for individuals.
What can cause this fact is both the individual need to be surrounded by the newest models and electronic gadgets. But developers, designers, web and app owners also impact it because:
(...) if we build web applications that require the user to have up-to-date, powerful devices, people throw away old devices much more frequently. This isn’t just bad for the environment, but it puts a disproportionate financial burden on the poorest in society.
Designing and building websites that don't force anybody by their weight and the way of performing to buy the newest device can help to reduce CO2 emission.
- The way we use the web itself
And then there's always this factor, dependent only on users that have an impact on climate change - what are their customs and behaviors while using the devices and surfing the web. It is up to the end-users how they use the internet: from streaming videos (which takes up a lot of bandwidth) to downloading files (which takes up a lot of memory space), from shopping online (which means more deliveries) to playing games online (which means more data usage).
Whether you are a developer, investor, teenager watching Youtubers, or person working as a vet in the local pet care, you probably are an end-user too. Therefore, you can ask yourself those questions and many similar others that can help you think if you are a mindful user:
- If you subscribe to newsletters that you never read?
- Do you waste your time by unconsciously scrolling through social media
- Are you addicted to watching all-new TV series on streaming platforms?
- Do you play the music only from streaming, or do you use CDs and music files you bought and collected through previous years?
Look at your behavior and check how you can improve your digital experience to be more planet-friendly.
How can we measure the website’s carbon footprint?
Calculating carbon emissions for the web is difficult because the system constantly changes. Multiple factors contribute to carbon emissions, for instance:
- The number of servers,
- Their location,
- How much electricity they use,
- How much power each server uses when it's on and off,
- The energy of building the data centers,
- Manufacturing the servers,
- Producing the cable and wireless network infrastructure,
- Web data transfer, so its weight and how many connections API it has,
- The type of connection, 3G or Viber,
- Energy used by the end-users,
- The country where the end-user is while transferring data (it's up to the dominating source of power in the country),
- Producing end-user devices,
- And many more.
Not all of them, unfortunately, can be measured, but there are the most critical factors that can help to estimate the website's carbon footprint:
1. Data transfer
2. Web data energy intensity
3. Sources of energy for data centers
4. Carbon intensity of electricity
5. Visits on the page
Soon we will publish an article that explains those complicated calculations. But for now, if you want to learn more about it, we recommend visiting the Website Carbon Calculator and Sustainable Web Design. Both explain key metrics and formulas for measuring carbon emissions by the website.
The Covid-19 impact on the web carbon footprint
Covid-19 has had a significant impact on the usage of the internet and website carbon emissions.
It is estimated that internet use during Covid-19 has increased by more than 30%. According to the International Telecommunication Union (ITU), the number of internet users grew by 800 million during the COVID-19 pandemic, from 4.1 billion in 2019 to 4.9 billion in 2021.
The pandemic transformed life and internet behavior - many workers had to leave their offices and work remotely, using video calls, conferencing, and other internet tools to communicate and fulfill their professional obligations. Children changed classrooms for the online teaching system, staying on call for a few hours daily with their teachers. Individually, due to the lack of meeting possibilities and other "offline" entertainments, we started to meet more people online or surf the internet, scroll and publish on social media, stream videos, and play games. We also began to shop more online and order food at the restaurant via apps and websites.
The fact that the whole of the world was obligated to stay at home and use online tools to work, educate and communicate with others caused an enormous impact on the web's carbon emissions.
The volume of online data has exploded. This means that all of the forecasts above for growth in internet energy consumption will need to be revised upward.
Make the web a greener place
Awareness. That's the point where all of the action can start. Websites are not immaterial things floating around in the metaphysical space of virtual. They have their weight built with data, and by using them, visiting, transferring, downloading, and uploading, we need an appropriate amount of electricity for those processes.
For each metric, the ideal figure to minimize emissions would be zero. The ideal amount of data transfer to minimize emissions is 0 KB, the ideal amount of data storage is 0 MB, and the ideal distance from data center to web visitor is zero miles. You get the idea—if all the figures are zero, then the carbon emissions will also be zero.
In the new modern world, when we transform most of actual life into its virtual side, it will be crucial to be aware of the web's impact on carbon footprint. However, we can still make a change with conscious decisions by end-users and mindfulness and a knowledgeable approach to sustainable web design by web creators. The second ones can set kind or carbon budgets for websites and choose green hosting. From both sides, we can create an internet community aiming (unfortunately not reaching) to the idea of website carbon neutral and net-zero web emissions, and therefore to slow-down unavoidable climate changes which have a place even now.
Greenwood Tom, Sustainable Web Design, 2021
McGovern Gerry, World Wide Waste, 2020
Jungblut Sarah-Indra, What’s the Carbon Footprint of Your Website?,
Reset. Digital for Good, 16.01.2020
Cisco Annual Internet Report (2018–2023) White Paper,
Updated: March 9, 2020
Jones Nicola, How to stop data centres from gobbling up the world’s electricity, Nature.com, 12 September 2018
Bulao Jacquelyn, How Much Data Is Created Every Day in 2022?,
Techjury.net, Jun 03, 2022
Greenwood Tom, Greening the Web: How We Can Create Zero Carbon Websites, Kinsta.com, June 24, 2022
Griffiths Sarah, Why your internet habits are not as clean as you think,
BBC.com, 6th March 2020
Chan Delle, Your website is killing the planet, Wired.co.uk, 22.03.2021
Belkhir Lotfi, Elmeligi Ahmed, "Assessing ICT global emissions footprint: Trends to 2040 & recommendations", in: "Journal of Cleaner Production" Vol. 177, 10 March 2018
This article emits ~0.04g of CO2.