The Carbon Footprint of Browsing the Web

WRITTEN BY Jack Geraghty

April 9, 2022

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The Carbon Footprint of Browsing the Web

Jack Geraghty

9 Apr, 2022

Over 35 billion tonnes of CO2 are being emitted each year and with 4.8 billion people browsing 1.8 billion websites, maybe it’s time to look at measuring the carbon cost of browsing the web and taking action. University College Dublin Computer Science Ph.D student Jack Geraghty analyses the implications of our internet use. 

The way we use the internet has completely changed in recent decades. It’s gone from slow, wired internet connections for desktop computers to having any amount of 4K content in our pockets. With this change, the amount of time spent on the internet and the way in which we access it has changed. 

Browsing the web isn’t free. Each time a user requests a web page, data needs to be processed and sent over a network and then back to the user. The more data that needs processing, the more energy consumed. Work is done on both the client side and on the server side. This complicates measuring the full energy usage as to do so would require access to the servers of the website provider. 

Some Notes/Disclaimers

The experiment detailed below was carried out using a single desktop PC. There is a significant amount of mobile browsing which has not been included in the analysis. The energy measurements are specific to a power model developed to the specs of the PC used for the experiment, other PCs will have different measurements. Any CO2 emissions were calculated using the carbon intensity of Ireland unless stated otherwise.

Photo Credit: Browsing Cafe © Syda Productions |

The Energy Consumption of Websites

To try and get some estimate of the energy consumption of browsing a website, Beeyon’s Papillon Energy analysis tool, a data centre energy management tool, was used to measure the amount of energy consumed by different web browsers when browsing a range of websites.

These websites were tested across three different browsers, Firefox, Microsoft Edge and Vivaldi (Chrome, unfortunately could not be tested).

Four categories (News, Retail, Social Media and Video Streaming) were identified and for each category four popular websites were selected to perform the energy analysist. The energy consumption of browsing each site for 10 minutes was then measured several times. This can be converted into the equivalent carbon footprint by multiplying the energy in kWh by the Carbon Intensity (for Ireland = 0.3 Kg/kWhr).

The amount of energy consumed and the amount of carbon produced over a ten minute period for each category, averaged across the websites tested. These are small numbers compared to the 35 billion tonnes emitted globally. Things get a bit more interesting when you start to scale these numbers to account for many users.

The effect of scaling up the amount of users. Obviously this number is much larger than the impact of an individual. It’s also not uncommon for a lot of websites to have more than 1 million users per day and they’re also likely browsing longer than 10 minutes. 

53 Tonnes CO2 per month for every 10 million users browsing on a desktop for ten minutes is minuscule in the context of 35 billion tonnes/year. However, this small number becomes very large when mobile devices are considered due to the vast number of these devices and the extensive amount of time that is spent on them every day. 84% of the world’s population now have mobile phones, 6.7 billion people. Assuming that the average 155 minutes utilisation (2.5 hours approx.) is spent browsing with a 3 W smart phone, this equates to 50 million kWh per day. Taking the EU average carbon intensity 0.25Kg/kWh this activity generates12,500 tonnes CO2/day. Over a year, smartphone browsing will produce 4.5 million tonnes CO2/year.

Keep in mind that this is the energy consumed and carbon emitted in the process by the browsing device. Data has to arrive at the device and the energy involved in transmitting data expends between 0.01 and 0.05 kWh/GByte. 2.5 quintillion bytes are generated each day by humans (1018 bytes…that’s an awful lot of data, and it is growing exponentially). It is impossible to calculate how much of this data is sent into the internet, but it is not unrealistic to assume that just transmitting data of this order and will contribute a further 100 million tonnes CO2/year.

Measuring and Reducing the Impact of Browsing and Searching

We have looked environmental impact of the end browsing device and the transmission of the data, the last element in the chain is the server hosting the website. This is rather difficult to calculate because it depends on the location and efficiency of the  hosting data centre. However, there are website carbon calculators that accept website URLs and calculate the cost per website visit and rank its relative environmental impact. Websitecarbon is such a site and worth a visit as it explains the cost of a visit in everyday terms and how much of an offset is required to make it  carbon-neutral.

Additionally, it you want to pursue carbon-neutral searching on the internet, use this search engine:

Ecosia offset the carbon footprint of searching the internet by planting trees in over 30 countries, funded by on-site advertising. To date, they have planted over 140 million trees.

So, what are the lessons we can learn from these statistics ?

Over the past decade the median size (total amount of data transferred relating to a web page) of desktop web pages has increased 341% and 1206.4% for mobile web pages. We know that smaller files use less energy to process, so if a web developer can keep their website simple and minimal in terms of the amount of data transmitted (i.e. keep video and streaming to a minimum) they can reduce the total amount of CO2 emitted as a result of them running their service.

It’s important to remember that software has an environmental impact and that by being aware of this during development and keeping a minimalist mindset, it can help reduce the carbon footprint of developers, companies and business owners.



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