Did you know that writing an email can send 17 grams or more of carbon dioxide into the atmosphere? Or that going audio-only on Zoom calls reduces carbon emissions by up to 96%?

It’s easy to think of our computers as clean, green productivity machines — it’s not like there’s a smokestack sticking out of our laptops or a tailpipe at the bottom of our smartphones. Still, internet use comes with an invisible carbon footprint. Every search query, podcast download and Netflix binge requires the use of energy, water and land.

How Does Using The Internet Create Carbon Emissions?

How can the internet cost environmental resources like energy, water and land to use? Large rooms filled with servers (data centers) require electricity to store and transmit data, and producing all that energy electricity emits carbon. Where do we store it all? Enter the land footprint, with masses of land dedicated to these numerous rooms filled with servers that send information to and from your laptop or smartphone. Don’t all those servers running all the time next to each other overheat? Enter the usage of water. Data centers run hot and liquid is used to cool it all down. Air conditioning is used too — adding to the electric bill and the carbon footprint. The result? Internet activities, even small mundane ones, come with a tiny tax to the environment — a tax that compounds when we consider the internet’s scale. Newer technologies like ChatGPT and generative AI are only making that footprint bigger, not smaller.

How much bigger? Let’s talk numbers. Here is the invisible carbon footprint of just a few internet activities:

Video Calls

Video call usage skyrocketed at the start of the pandemic. From 2019 to 2020, Zoom went from 10 million daily participants to 300 million. Nowadays, in 2023, the number is more than double.

But videoconferencing comes at an energy cost. According to a study by Purdue University, a one-hour Zoom call produces between 150 to 1,000 grams in carbon dioxide. Comparatively, a gas-powered car burning a gallon of gasoline emits 8,887 grams of carbon dioxide, potentially making your Zoom calls more green than driving to meet your colleague in person. But that same one-hour call also requires between two and 12 liters of water and an iPad Mini’s footprint worth of land mass (those data centers filled with servers for all those Zoom calls have to go somewhere).

All that is for a one-hour call. Now multiply that by the 55 billion hours of Zoom meetings that take place in a year. We said it above and we’ll say it here too: you can reduce the footprint of your call by 96% by going audio-only. Next time you get called out for going face mute, tell your coworkers you’re saving the planet!

Downloading Podcasts

You probably know by now about Mozilla’s IRL Podcast. Surely you’ve listened to our most recent season 6, where we discussed how AI appears in and affects our real world. But if you’ve listened to the show for a while, you’ll know season five contained an episode on the carbon footprint of the internet, including podcasts.

In the episode, we tallied up the amount of carbon dioxide an average installment of the IRL podcast produces. The answer: an average podcast episode emits 1.16 metric tons of carbon dioxide (that equates to the same amount of harm as around three barrels of oil per episode!). Where does most of that waste come from? Mainly electricity and how it’s produced. Some electricity is made using harmful sources like coal or natural gas. Or it can be created using less harmful sources like wind and solar. IRL Podcast took an average between those sources and arrived at 1.16 metric tons of carbon per episode.

Streaming Video

200 million subscribers, 3+ hours of video per day: popular sites like Netflix stream a lot of video to a lot of people each day. One study found that the average Netflix users collectively download 18 million terabytes worth of data in a month.

So what’s the carbon footprint of all of this? According to Netflix in 2020, the company says one hour of streaming video on the service produces 100 grams of carbon dioxide equivalent (CO2e). One person watching four hours of Netflix is like driving a gas-powered car one mile. Netflix can produce around 1.1 million metric tons of carbon dioxide annually — the equivalent of 240,000 passenger cars.

The streaming media picture is obviously much bigger than Netflix. A study published in January counts annual carbon emissions at around 6.5 million metric tons of CO2e for YouTube. TikTok’s carbon footprint is more than double YouTube’s. TikTok produces around 14.7 million metric tons of CO2e per year.

Using AI

Before you or I can use a product that incorporates AI, software engineers need to train the AI, instructing it on the things it needs to know. This training can be extremely costly to the environment.

The energy needed to teach an AI model like ChatGPT could power an average American’s home for hundreds of years — this is how Gizmodo sums up a research paper by Stanford’s AI division. Other estimations measure the amount of energy used to train ChatGPT at 1.3 gigawatt hours, or the amount of energy that 120 U.S. homes use in a year.

Not every AI is similar in this regard. The paper compares the training of four major AI models, including ChatGPT, and ranks the energy-efficiency of the data centers used to train the four AI models. ChatGPT’s GPT-3 released the most carbon into the atmosphere, 500 metric tons worth. Compare this to the AI model BLOOM which is similar in size to ChatGPT but emitted 22.7 metric tons of carbon dioxide. Much less in comparison, but still sizable — training BLOOM consumed more energy than the average American does in one year.

Those are some gassy lessons. And that’s just to train the AI tools, not use them. It isn’t fully clear just how much a service like ChatGPT costs to the environment with each use, but some estimate that ChatGPT emits 7.6 metric tons of carbon dioxide into the atmosphere each year.

The kicker? Groups are solving AI’s carbon problem with, you guessed it, more AI! Models like BCOOLER are being used to optimize energy usage.

A Disproportionate Impact

The environmental impact of streaming video or chatting with ChatGPT doesn’t affect everyone equally. Lorena Regattieri, a senior Trustworthy AI fellow here at Mozilla Foundation, notes, “In the era of AI and internet services at scale, it is crucial to critically examine the impact of our digital consumption on the environment and marginalized communities, particularly in the Global South.” In addition to the toll it takes for computers to process all this info, Lorena points out that creating the computers themselves comes at a cost too. “The extraction of minerals like lithium, cobalt, and rare earth elements for technology components often occurs in regions with environmental and social concern,” says Lorena. “These issues disproportionately impact marginalized communities, particularly in the Global South, where mining operations can harm local ecosystems and communities.”

So what can we do?

At the top of this article we mentioned the ability to reduce Zoom call emissions by over 90% just by switching to audio only. There are other tips you can take advantage of, like using a search engine like Ecosia to help plant trees, turning off autoplay on video sites you visit or cutting back on unnecessary newsletters. But, really, the onus should be on the companies that create these apps and services which can make broad, sweeping changes with better choices.

If you’re wondering what you can do, here’s Lorena with a few tips:

• Opt for energy-efficient devices (and support companies that prioritize using renewables)
• Demand transparency from companies regarding their carbon emissions
• Support initiatives that make use of clean energy for computing, like Mozilla Awardee Solar Protocol
• Support movements and global organizations that advocate for fair working conditions and the protection of communities impacted by the tech supply chain. A few examples: Fairwork, Foxglove in the UK and OCP over in Brazil
• Consider the environmental impact of device production and disposal. Recycle electronic devices through certified e-waste programs or donate/sell functioning devices you’re done with instead of trashing them

Or, if you work for a tech company and are reading this, here’s what you can do to create sizable change:

• Optimize algorithms and models for energy efficiency
• Power data centers with renewable energy and implement proper waste management
• Establish responsible sourcing policies that prioritize environmental sustainability and respect for indigenous rights

The Internet’s Invisible Carbon Footprint

Written By - Xavier Harding

Edited By - Audrey Hingle, Carys Afoko, Kevin Zawacki, Tracy Kariuki

Special Thanks: Lorena Regattieri!