28 February 2020
Every time you search the internet or stream a video, a computer in a data centre somewhere in the world spins into action. With internet use ever on the rise, there have been fears that this is driving a big increase in energy consumption, undermining efforts to limit climate change.
The good news is that according to the most detailed study to date, the energy use of data centres has risen just 6 per cent, despite a 550 per cent increase in demand. Dramatic improvements in efficiency have almost cancelled out the big increase in use, according to Arman Shehabi at the Lawrence Berkeley National Laboratory and his colleagues.
And that’s not all. Video streaming in particular has been singled out as a major driver of rising energy use, with several media outlets reporting that the emissions generated by watching 30 minutes of Netflix are the same as driving almost 4 miles.
This claim is based on figures in a 2019 report by the Shift Project. But according to an analysis by George Kamiya at the International Energy Agency published by CarbonBrief on 25 February, errors in those figures mean it overestimates emissions from viewing Netflix by a whopping 30 to 60 fold.
So does this mean we can stop worrying about the climate impact of internet traffic and streaming videos in particular? Not quite.
The main conclusion of the Shift Project report was that the transmission and viewing of online videos generates 300 million tonnes of carbon dioxide a year (mtCO2), or nearly 1 per cent of global emissions, as New Scientist reported (we never reported the unlikely driving claim).
Kamiya thinks the Shift Project did overestimate overall streaming video emissions, but his analysis applies only to Netflix. “I haven’t done any estimates of the global emissions from all streaming video,” he says. “This would require quite a bit more analysis.”
The author of the Shift Project report, Maxime Efoui, says his team welcome a transparent discussion and will be contacting Kamiya to discuss the differences in numbers. Kamiya makes the same recommendations as the report did, Efoui points out, so these will not change.
However, an independent study by Chris Preist at the University of Bristol, UK estimated that YouTube alone generates 10 mtCO2 a year, and Preist says nothing in Shehabi or Kamiya’s work alters this conclusion.
According to the Shift Project, YouTube accounts for less than a fifth of total streaming emissions. If that is correct, overall emissions due to streaming would still be more than 50 mtCO2 a year – a lot less than 300 mtCO2 but still substantial.
And while big efficiency gains appear to have limited the rise in energy demand from data centres, we can’t assume that this will continue, says Shehabi. Data centres may already have implemented all the easy wins.
Meanwhile, Anders Andrae, an efficiency researcher for Huawei based in Sweden, thinks Shehabi’s team has got it wrong. He is sticking with his forecasts of huge rises in electricity demand due to the internet and computing.
Resolving these conflicting numbers will not be easy. We have very little data on the data industry, as companies do not disclose much. All studies are essentially educated guestimates.
Another complication is that rising energy use in this sector might sometimes lead to lower demand in others. For instance, demand for streaming video might shoot up this year if millions of people are forced to spend more time at home because of the coronavirus outbreak. But if they are doing this instead of driving or flying places, overall emissions will be much lower.
“Netflix and chill might be one of the more energy-efficient things you can do,” says Shehabi.
Journal reference: Science, DOI: 10.1126/science.aba3758
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