We worry about emissions from car journeys and flights. We worry about the damage our diets do to the environment. We even worry that using too much paper contributes to deforestation.

But few of us ever stop to think about the damage our browsing habits are doing to the world.

Let’s change that. Consuming digital media comes with an environmental cost. A big one. And we should all understand what contributes to it.

At a time when we’re thinking about changing our cars and changing our diets, we should also be thinking about changing the way we use our devices.

How We Consume Digital Information

Before we can look at the environmental cost of consuming digital media, we need to understand what happens when we look up Apple News on our iPhones or browse The New York Times on our laptops.

There are three main areas that create energy demand: the device we use for browsing, the network that powers the connection and the data centers that host the content. When you load a website or open an app, your smartphone sends a request over Wi-Fi to the data center that stores the information. That data is then sent back virtually instantly to your phone and, presto, the website loads.

Energy and natural resources are needed to power this system, note Greenpeace’s Gary Cook and co-authors. Powering all of our devices requires the most energy, then networks, then data centers. And let’s not forget that it requires energy to manufacture all of the hardware.

Let’s take the components of this system one by one to get an idea for how much of a carbon footprint our consumption habits have.

Polluter No. 1: Data Centers

The entire digital world is stored in vast data centers spread across the globe. And those data centers guzzle electricity.

Nature’s Nicola Jones reports that data centers use around 200 terawatt-hours of energy each year. That’s more than some countries and half of the total energy needed to power the global transport system.

The problem is that almost all of that energy is dirty. Take Virginia’s Data Center Alley, which about 70 percent of internet traffic passes through. Greenpeace’s Clicking Green Virginia study, authored by Gary Cook and Elizabeth Jardim, found that just 5 percent of the energy used there is green. The rest comes from non-renewable sources. Worse still, the growth of Data Center Alley “continues to fuel and increase demand in coal and natural gas.”

Data centers have become more efficient over the last decade, notes Tachyum’s Radoslav Danilak. More efficient technology has been introduced such as server virtualization and solid state hard drives. As have better cooling systems. Google, for instance, now has a power usage effectiveness of 1.12 across all data centers, says Radoslav. That’s not far away from a perfect 1.0 score.

Big tech companies understand this, and in the past several years they’ve made efforts to keep their operations a little more sustainable.

“The good news is that a number of major Internet companies have begun taking big steps to green their cloud,” reporter Bryan Walsh wrote for Time in 2014. He reported that Apple’s iCloud was being powered 100 percent by renewable energy. The company also built what at the time was the country’s largest solar farm at its North Carolina data center. It also began powering its Nevada data center with solar and geothermal energy. Facebook, too, had pledged to use 100 percent wind power at its data center in Iowa.

But all of the easy efficiency optimizations have now been made. Without radical new technology, further efficiency gains will be minor.

What’s more, many servers aren’t yet fully running on renewable energy, reports Greenpeace’s Cassady Craighill. In Virginia, Facebook is at 37 percent, Microsoft 34 percent and Google at 4 percent. The big problem, though, is Amazon, whose data centers use just 12 percent renewable energy. Amazon’s AWS is the world’s largest cloud computing provider and powers platforms like Netflix, LinkedIn and Facebook. Even if you wanted to cut Amazon out of your life to lower your own carbon footprint, it’s virtually impossible, as reporter Kashmir Hill found out.

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Polluter No. 2: Networks

A massive infrastructure that includes ISPs, modems, cell towers and thousands of miles of cables is needed to get information from the data center to your device. This, too, has a significant impact on the environment.

It’s one that isn’t often reported, however, say Daniel Schien and Chris Preist at the University of Bristol in England. The pair, who co-authored a study on the energy consumption of YouTube, point out that tech companies report carbon emissions from data centers but never include the rest of the network. This is important because it’s often the journey from data center to device that uses the most energy. Their study found that the total carbon footprint of YouTube when everything is taken into account is 10 million metric tons of carbon, equivalent to a city the size of Glasgow, Scotland.

The last mile of transfer matters most, says Lutz Stobbe, a researcher at the Fraunhofer Institute for Reliability and Microintegration. Data transfer to mobile phones uses the most electricity, as it suffers from the most transmission loss. Copper cables used in broadband are also much less efficient than fiber-optic cables, says Stobbe.

According to a report by The Centre for Energy-Efficient Telecommunications (CEET) in Australia, wireless networks account for 90 percent of total cloud energy consumption, compared to 9 percent for data centers.

What’s being transferred matters, too. Deutsche Welle’s Jeannette Cwienk points out that the vast majority of data transferred online is video.

“The problem: transferring videos online is data-intensive. In 2018, online video traffic was responsible for more than 300 million tons of CO2, equivalent to what a country the size of Spain releases in a year — for all sectors combined. The higher a video’s resolution, the more data that’s required.”

As technology advances, the environmental cost of networks may grow significantly. Take 5G, for instance. The high-frequency waves used by 5G don’t travel half as far as 4G waves, notes science and tech writer Kashyap Vyas. That means many, many more antennas will need to be erected to provide adequate reception. These won’t be as large as traditional cell towers, but their creation will still have an impact on the environment.

Polluter No. 3: The Devices We Use

Finally, we come to the devices we use to consume digital media. Both their use and manufacture have a footprint.

The Guardian’s Christopher Hodgson believes that when everything is taken into account, devices account for the largest part of a digital media carbon footprint. In the case of The Guardian, almost half of the company’s digital footprint is created by readers’ devices.

Smartphones are particularly damaging to the environment, says Fast Company’s Mark Wilson. First, they are considered disposable, with consumers choosing to upgrade every couple of years on average. But the cost of building phones accounts for almost all of the device’s carbon footprint over two years. “That means buying one new phone takes as much energy as recharging and operating a smartphone for an entire decade,” Wilson writes.

Smartphones will soon dominate laptop and desktop devices when it comes to energy consumption, say McMaster University researchers Lotfi Belkhir and Ahmed Elmeligi. Between 2010 and 2020, the pair estimate that the carbon footprint of smartphones will increase from 17 megatons of CO2 to 125 megatons.

Then there’s the cost of disposing of electronic devices once we’ve finished using them. “E-waste management is an urgent issue in today’s digitally dependent world, where use of electronic devices is ever increasing,” says Houlin Zhao, secretary-general of the International Telecommunication Union (ITU).

A report by the ITU found that almost 45 million metric tons of e-waste were created in 2016, more than 3 million tonnes more than in 2014. Expect more than 50 million by 2021. Further, only 20 percent of that e-waste was recycled in 2016.

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Our Digital Media Carbon Footprint Could Grow Exponentially

Internet use is going to soar in the next few years. Cisco predicts that internet traffic between 2018 and the end of 2022 will be more than in all previous years combined. Specifically, global internet traffic will increase from 122 exabytes per month in 2017 to 396 exabytes per month by 2022. There will also be an additional 1.4 billion internet users in 2022 compared to 2017.

That’s going to lead to a big increase in the amount of environmental damage caused by our digital world. Research by The Shift Project, a think-tank in Paris, has found that current levels of digital consumption aren’t sustainable. Digital technology’s share of global greenhouse gases increased by half between 2013 and 2019, moving from 2.5 percent to 3.7 percent. In six years’ time, it’s likely the figure will be above five percent.

The trouble is most people just don’t think about how their digital consumption impacts the environment, says socio-technical researcher Danah Boyd. At most, they think about the impact of the physical materials needed to build smartphones and laptops — but not abstract things like the cost of keeping every notification or email you’ve ever received, all of which are stored on servers that need to be powered at massive environmental cost.

For the most part, there’s no escaping the environmental impact of our media consumption, digital or otherwise. But we still have a role to play. Limiting mindless browsing, holding onto devices for longer than a couple of years, supporting tech companies that go green and boycotting ones that don’t are just some of the measures we can take to make our digital media consumption greener.

Images by: Nathan Dumlao, Taylor Vick, Bruce Mars