In the past 24 hours you might have watched a video recommended by YouTube, played a videogame in the cloud or asked a digital assistant to play your favourite song. These services, triggered by a tap, swipe or voice command, are delivered in an instant – cleanly, wirelessly and noiselessly – and it may never have occurred to us what impact they have on the environment.
But every innovation delivered across the internet is run from data centres, colossal buildings as big as nine hectares, situated well away from prying eyes in deserts or tundra. The statistics for their power usage are eye opening.
Some estimates predict that by 2025, data centres could be responsible for 20 per cent of global energy consumption, and bearing in mind Greenpeace's analysis that only 20 per cent of that electricity is renewable, it represents a significant burden on the environment. And yet it's all being driven by us, by streaming videos, using artificial intelligences and interacting with the cloud.
"The problem is quite literally 'out of sight, out of mind'," says Dr Matt Brennan, a reader in popular music at the University of Glasgow, who has studied the environmental impact of music streaming.
"We don't see the infrastructure that enables electronic devices to perform their magic. We have a better understanding that air travel has a big carbon footprint, because we get a glimpse of that infrastructure every time we walk through an airport. If you had to sit in a warehouse surrounded by towering servers every time you used your phone to pull data from the cloud, you'd have better awareness of the relationship between those worlds, as well as their environmental impact."
The loudest complaints on this subject have been directed at one sector in particular: cryptocurrency. The mining of Bitcoin has often been criticised for its enormous use of energy; 18 months ago the website Digiconomist estimated that the electricity used to mine Bitcoin was greater than the consumption of 159 different countries.
Last week, Christian Stoll at the University of Munich gave a bleak assessment of the situation to Wired magazine. "Coal is fuelling Bitcoin," he said.
But while cryptocurrency is considered environmentally damaging by those who see it as frivolous and unnecessary, there's a much broader problem: all number crunching requires energy, and all our digital habits require number crunching. This month, researchers at the University of Massachusetts published a paper on the environmental impact of training AI models, specifically speech recognition, and discovered that the carbon footprint of one such process is comparable to that of the entire life of one human being by the team they reach the age of 56. Technology consultant Rob Griffiths was quick to point out on Twitter why this was bad news. "Because most obviously, we're only at the start of this global race to build more complex systems," he said.
Among these systems are subscription services that we access via the cloud rather than locally on our own devices, such as Netflix, Spotify, Office 365 and Photoshop. In November, Google will launch a streaming videogame service, Stadia, which replaces the gaming console with the cloud, but environmental systems analysts have suggested that this is not a greener option. "Cloud-gaming will virtually always entail substantially more overall energy use than gaming on a local client," Evan Mills, leader of the Green Gaming project, told Digital Trends.
This mirrors Brennan's findings when he looked into the environmental impact of streaming music compared to listening to traditional music formats. Simply because there are no moving parts doesn't mean there's no energy consumption. Far from it.
Many services force us to use more energy than we really need to. YouTube is frequently used to listen to music rather than watching videos, and last month researchers at the University Of Bristol released a study suggesting that were YouTube to introduce a feature that turned off video that wasn't being actively watched, it could reduce annual carbon emissions by an amount equivalent to 50,000 cars. The authors of the study called such things "digital waste". Yes, data might be easy to store and easy to retrieve, but bloated design or unnecessary convenience can add up to an alarming use of energy when millions of users are involved.
These sums aren't arrived at easily. Some claim that using data centres leads to unacknowledged efficiencies in the workplace or in the home, but the biggest cloud providers, Amazon, Google and Microsoft, are under increasing pressure to take ecological issues seriously.
At an Amazon shareholder meeting last month there was a failed attempt to force the company to reveal its carbon footprint and reduce its use of fossil fuels that, according to Amazon's own figures, still power half of its data centres.
Microsoft and Google have taken more positive steps, with the former aiming for 70 per cent of its data centres to be powered by renewables by 2023. Google says it is committed to a 100 per cent renewable energy "match", meaning that for every kilowatt hour the company consumes, they buy a kilowatt hour from a renewable source.
But Brennan says he believes that a shift to cleaner energy doesn't suddenly make the technology environmentally sustainable. "It's a fallacy," he says. "Any successful effort to address climate change is going to require a change in behaviour, in addition to technological change, on a massive scale."
One company, Carbon Relay, is now using AI to try to minimise the environmental impact of data centre usage, a kind of fighting fire with fire approach. Founder Matt Provo says it's not merely corporate conscience that's triggering the hunt for efficiencies, but it's because consumers are starting to demand it.
"Brand perception is more important than ever and our clients understand that by investing in our platform they're able to show they are doing good," he says. "Many companies see the connection between investing in environmental, social and governance initiatives and increasing the value of their brand."
If our carbon footprint is something we care about, the course of action is clear: recognise that our everyday use of technology is unlikely to be carbon neutral, and use services that commit to using the leanest code, the most efficient data centres and the cleanest sources of energy.