20 | New Scientist | 16 November 2019
ONCE, we had to wait to watch
television programmes when they
were broadcast. Now, video on
demand is taking over. Globally,
more than 600 million people
subscribe to streaming services
like Netflix, and so many services
exist that it is hard to keep track.
This month alone has seen the
launch of Apple TV+ and Disney+.
This is great if you are excited
about Jennifer Aniston’s return
to the small screen, or the prospect
of a Star Wars TV show, but it isn’tso great when it comes to
climate change. According to
one estimate, online videos
generate 300 million tonnes
of carbon dioxide a year, or nearly
1 per cent of global emissions,
and this is forecast to soar.
This puts streaming in the same
league as flying, which produces
around 2.5 per cent of global
emissions. Can it be true? And
if it is, can’t streaming be made
green by using renewable energy?
With broadcast TV, each
transmitter uses lots of power
to deliver TV signals directly
to a huge number of people.
But downloading or streaming
video requires more equipment
and energy because it is one
to one, not one to many.
When you hit play on the next
episode of your latest binge-watch,
the request goes out to a vast data
centre full of computers, which
sends the video file in return.
The video typically goes to a
Wi-Fi router in your home that
may send the signal to yet
another box before it reaches
the TV. Or, if you are watchingon a phone, the video may be sent
over the cellular network.
Totting up the resulting
greenhouse gas emissions from
all this is far from simple, but there
have been a few attempts to do it.
One, by Chris Preist and Daniel
Schien at the University of Bristol,
UK, looked at YouTube.
Earlier this year, they reported
that the total emissions from
people watching YouTube globally
in 2016 was the equivalent of
10 million tonnes of CO 2 – the
same as from a small country
such as Luxembourg. Mobile data
accounts for the biggest chunk of
that because sending data to
phones takes more energy than
sending it down a cable (see graph,
right). YouTube is a special case,
though, as people are more likely
to watch it on the go, says Preist.
The astounding figure of 1 per
cent of all global emissions being
due to online video comes from abetter than driving to a shop to
hire or buy a DVD. In fact, a 2014
study estimated that the switch
from DVDs to streaming video
would lead to a small drop in
emissions in the US.
But streaming video is worse
than broadcast TV, because it
happens in addition to broadcast
and the energy used to transmit
video increases with the number
of viewers. Everyone expects
video streaming and thus the
associated emissions to rise fast.
“Globally, loads more of us are
doing it,” says Preist.
The growth of high-speed 5G
networks will play a big part in
this, by making it possible to
download data faster. 5G uses
less energy per byte than 4G,
but energy usage will rise overall
as people use more data.
So what can we do? Many
streaming firms say they are
using renewable energy.
“We match 100 per cent of the
power we use, and the power
our partners use, through
renewable energy and carbon
offset projects,” says a Netflix
spokesperson. “We prioritise
use of renewable energy,” says
an Apple spokesperson.
However, buying renewable
energy from existing wind or solar
farms does little to stop emissions
rising. What matters is whether
companies are creating additional
renewable energy sources to cover
the increased demand. This is
something environmental
organisation Greenpeace looks at
in its Click Clean report evaluating
the green credentials of tech firms.
In the most recent report in 2017,
Netflix scored a D for not investing
directly in new renewables, says
the report’s lead author Gary Cook.
“They have not really improved,”Ooh, just one more
episode? Maybe not...Online streamingSE
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Estimated share of global CO 2
emissions due to online video
News Insight
The dark side of bingeing
Streaming video services like Netflix, Apple TV+ and Disney+ are on the
rise – but so are their carbon emissions. Michael Le Page reportsFrench environment think tank
called The Shift Project. It says
that digital technologies produce
4 per cent of greenhouse gas
emissions, with end devices
being the single biggest source
and data centres a close second.Growing emissions
The Shift Project says the
streaming of movies and TV
shows by companies such as
Netflix accounts for 34 per cent of
the emissions due to video alone.
This is followed by pornography at
27 per cent, with other streaming
such as YouTube and videos on
social media making up the rest.
There are uncertainties, but
Preist thinks the overall emissions
figure is in the right ballpark.
However, this doesn’t necessarily
mean that video streaming has
led to a big rise in emissions.
Watching a movie on Netflix is