Modern life increasingly is defined by the activities we engage in online: Zoom meetings at work, Netflix and Xbox marathons at home, and a steady stream of YouTube, TikTok, and Facebook video clips in the nooks and crannies in between.
There are many benefits to life online, yet there are also undeniable social, economic, and environmental costs. While global emissions from video streaming and other digital activities comprise somewhere in the neighborhood of 3% of the total,a the voracious and growing appetite for bandwidth is raising concerns about sustainability—and prompting some to wonder whether it is possible to keep up with the demand.
"We're seeing the digitization of everything—work, entertainment and shopping. There's a huge shift in lifestyle and it's sharpening the focus on how all of these devices impact things," says Eric Williams, a professor of sustainability at the Golisano Institute for Sustainability of the Rochester Institute of Technology.
As bandwidth demand ticks upward and carries the demand for power with it, "There's an emerging discussion about the role of all the digital services we've come to rely on," says Mike Hazas, a professor in the Department of Information Technology at the University of Uppsala in Sweden. "It's an important discussion, because how we design and use systems will define our future."
There's a common assumption that life online is cleaner and greener than life in the physical realm. There is near-zero cost to sending an email message or viewing a YouTube video. While it is true a Zoom meeting consumes only a fraction of the energy of a commute to work or a flight across the country, it does require bandwidth and electricity. Of course, as millions of people venture online for billions of video calls, the energy and bandwidth requirements accumulate, and can spike.
The ability to click and instantly watch videos—and even autoplay them in various apps—has changed behavior in profound ways. According to networking firm Sandvine, upwards of 60% of the traffic on the Internet is now related to consumer video streaming, and sites such as Netflix, Facebook, Instagram, TikTok, and YouTube carry the bulk of this traffic, which is growing at an annual clip of about 24%.b The Carbon Trust, an independent U.K.-based advisory organization comprised of experts in sustainability, reports that long-form video streaming accounts for 45% of all Internet traffic.c
Artificial intelligence, machine learning, deep learning, cryptocurrency mining, Blockchain, and the Internet of Things (IoT) are poised to ratchet up the stakes further. "These systems will add huge volumes of traffic to the Internet, and much of this traffic is automated and not constrained by users," says Kelly Widdicks, a post-doctoral researcher at the School of Computing and Communications at Lancaster University in the U.K.
The direct use of devices, and how they draw power and bandwidth, is not the only factor in understanding how they impact things, however. About 90% of the energy a smartphone uses during its life cycle is embedded in the manufacturing process.d This includes collecting rare materials for batteries, fabricating devices, and recycling and disposing of components. What's more, after a smartphone handset is produced, about 90% of the energy consumption takes place off the phone, including on the network and in the datacenter.e
Further complicating matters: fast, persistent Internet connections modify behavior. A 2021 study conducted by a pair of researchers at the U.K.'s University of Sussex, Bernado Calderola and Steve Sorrell, found that the availability of telework may actually encourage people to move farther from their place of work and engage in additional non-work-related travel. The authors noted that such "results provide little support for the claim that teleworking reduces travel." Widdicks says there also is evidence that as people expand their social footprints online, they sometimes travel more to meet others.
Indeed, the relationship between infrastructure and streaming is complex, Hazas says. Growth in infrastructure initially made it possible to offer streaming services, which over time came to be expected by consumers and streaming providers. This, in turn, has contributed to further growth in online infrastructure.
For now, there's no end in sight. The total footprint from digital technology (including manufacturing gadgets) is now on par with the airline industry, at approximately 2% to 3% of global carbon emissionsf Industry estimates predict that streaming video as a percentage of Internet traffic could reach into the 80% range within the next few years.
Understanding the real-world impact of streaming video, online gaming, and other digital activities is challenging. For one thing, devices continue to become more energy-efficient and smarter about how they use bandwidth. For another, "The equation varies greatly depending on the source of energy and the type of device someone uses," Williams says. Wind and solar energy create a very different cost structure than petroleum-based fuels. A 50-inch smart TV pulls 4.5 times more power than watching a video on a laptop, and 90 times more than watching it on a smartphone, according to the Carbon Trust.
For years, researchers and media outlets have inflated the carbon footprint of digital services. For example, Yahoo!, BigThink, Gizmodo, The New York Post, Phys.org, and others have reported that the emissions generated by watching 30 minutes of Netflix is the same as driving almost 4 miles (or 3.2kg CO2e (carbon dioxide equivalents) per hour). The figure originated from the Shift Project,g a French think tank, which later corrected this calculation downward by a factor of eight to 400g CO2e per hour.h A recent peer-reviewed study by researchers from Purdue and Yale universities and the Massachusetts Institute of Technology estimated that an hour of streaming Netflix emits 440g CO2e.i Yet another study published by researchers from Simon Fraser University claimed that 35 hours of watching HD video emitted 2.68 metric tons of CO2e, equivalent to 76kg CO2e per hour.j
It turns out that all these calculations missed the mark. George Kamiya, a digital energy analyst for the International Energy Agency in Paris, exposed these flawed calculations in a blog post published in February 2020k and updated in Decemberl His analysis showed that, on average, one hour of streaming video consumes power that results in the emission of 30 to 80g CO2e. "These earlier headline numbers [3.2kg CO2e per hour or 6.1 kW] didn't make sense to me," Kamiya says. "If true, this would be the equivalent to having over 60 big-screen TVs on at the same time."
A June 2021 white paper released by the Carbon Trust (partially funded by Netflix) confirmed that an hour of streaming video in Europe resulted in the emission of 55g CO2e, the carbon equivalent of boiling three kettles of water. In addition, using its own data, the BBC estimated that an hour on its streaming service, iPlayer, results in the emission of 33g CO2e per hour in the U.K.m
The story is also rosier at the datacenter level. In 2020, a group of researchers led by University of California, Santa Barbara professor Eric Masanet found that cloud-based datacenters account for only 1% of worldwide electricity use. Claims that giant datacenters would lead to catastrophic consequences have proved wrong. According to Google, the move to the cloud has resulted in up to seven times more computing output per datacenter than only a few years ago.n
Bandwidth concerns are another flash point. At the outset of the COVID-19 pandemic, Spanish telecom Telefonica, for instance, reported a 45% increase in data traffic. In fact, bandwidth demand shot up so fast that a top European Union official spoke with Netflix CEO Reed Hastings about switching to standard definition video if networks became too congested.o Havoc never ensued, yet fears persist that growing use of video streaming, online gaming, cryptocurrency mining, and artificial intelligence could eventually reach a tipping point and take down the Internet.
As 5G enters the picture, additional questions arise. While research firm IDC has reported that 5G delivers a 3x boost in spectrum efficiency and a 100x improvement in traffic capacity and network efficiency,p it's unclear what the overall impact will be, says Chris Bronk, an assistant professor in the Department of Information Technology at the University of Houston. "As you continue to add devices and introduce new technologies into the mix, the equation becomes a lot harder to figure out," he says. "There are estimates that 5G will pull 10 times as much power as LTE and increase bandwidth demands further but, in reality, nobody has a definitive answer."
Although reports of digital devices leading to the demise of civilization have been largely exaggerated, there are growing questions about what can be done to better manage both energy and bandwidth demands. Bronk points out that many ISPs and mobile providers already cap bandwidth. Customers who exceed limits pay steep fees, or wind up throttled down in speed, or even blocked from further consumption. Others have floated the idea of a consumption tax and tighter regulations about energy sourcing.
"Peaks are very rarely attained, even with the highest possible bandwidth services. There is absolutely no way to 'take down the Internet' with streaming."
Hazas says that one way to address growing video demand and bandwidth is to turn off the autoplay feature that streams one video after another on YouTube, Facebook, Instagram, and other platforms. Some organizations, such as the BBC, now stream video in standard definition by default, with high definition as an option for those viewing content on larger screens. Likewise, a recent study conducted at Purdue University also found that by turning off the camera during Zoom and Microsoft Teams calls, it's possible to reduce one's carbon footprint by 96%,q while streaming Netflix or Hulu in standard definition results in an 86% reduction.
Some, such as Dom Robinson, co-founder of consulting firm Id3as and an expert in content delivery networks (CDNs) and scaling streaming video, say that concerns over energy consumption are well-placed, but bandwidth fears are entirely misplaced. "A common myth propagated by vendors of streaming services is that there's a 'scarcity of resource.' The purpose of this is to decelerate a rapid commoditization of pricing for these services," he argues. ISPs and telecoms have enormous overhead in their networks, he says; "They are able to sustain many times peak network traffic. Peaks are very rarely attained, even with the highest possible bandwidth services. There is absolutely no way at all to 'take down the Internet' with streaming," he says.
In the end, Hazas believes it is vital to maintain a sense of perspective. Although information and communications technology will devour a greater share of electricity and bandwidth in the future, the overall carbon footprint for the sector has remained constant—and it could drop if efficiency gains continue.r
"The migration online is a net positive. If it comes down to Netflix or a drive to the local cinema, there's no doubt that Netflix is the better choice from an environmental perspective. … We need to pay attention to bandwidth and energy consumption and look for ways to improve efficiency and behavior. But there are much bigger problems, such as how we heat and cool our homes, use vehicles, and the foods we choose to eat."
Morley, J., Widdicks, K., Hazas, M.
(2018). Digitalisation, energy and data demand: The impact of Internet traffic on overall and peak electricity consumption. Energy Research & Social Science, Elsevier. 38: 128–137 https://doi.org/10.1016/j.erss.2018.01.018
Widdicks, K., Hazas, M., Bates, O., Friday, A.
(2019). Streaming, Multi-Screens and YouTube: The New (Unsustainable) Ways of Watching in the Home. In Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems, https://doi.org/10.1145/3290605.3300696
The carbon footprint of streaming video: fact-checking the headlines, IEA, December 11, 2020 https://www.iea.org/commentaries/the-carbon-footprint-of-streaming-video-fact-checking-the-headlines
Pelau, C., Acatrine, C.,
The Paradox of Energy Consumption Decrease in the Transition Period towards a Digital Society. Energies, 2019, 12, 1428; doi:10.3390, en12081428 www.mdpi.com
Carbon Impact of Video Streaming, June 2021. https://prod-drupal-files.storage.googleapis.com/documents/resource/public/Carbon-impact-of-video-streaming.pdf
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