Streaming a television show in standard definition can shave a little off your carbon emissions, scientists at the UK's Royal Society says.
4K video streaming - also know as Ultra HD - on a phone generates about eight times more in emissions than standard definition (SD), it says.
And, on a small screen, the viewer might not even notice the difference.
Platforms and regulators should limit streaming resolution and default to SD, the authors urged.
The scientists' report says digital technology’s estimated contribution to global emissions ranges from 1.4% to 5.9% of the global total.
Another simple way to save energy is for people streaming music to turn off any accompanying video if they’re just listening, not watching, the authors say.
They estimate such small moves could save up to 5% of the emissions from a streaming service – a reduction comparable to what’s achieved by running YouTube’s servers on renewable energy.
Keep phones longer
The report also suggests owning and using devices for longer before trading them in, because the emissions created in making a new device are significant.
Some of the numbers in the report are contested.
But it says that if you change your mobile phone every two years, the manufacturing represents about half of all the emissions it will generate through its lifetime.
But if individuals keep their phones for four years instead of two, that contribution is significantly reduced.
For the same reason, the report says buying a device second-hand - or sharing equipment - also reduce the share of so-called "embodied emissions".
Moving computing from home or business desktops and on to the cloud can also help, because the cloud allows more efficient patterns of server use - so they don’t consume energy while idle.
Tech firms must also play a part, by providing transparent information about the energy consumption of their digital products and services, the report recommends.
“There are many routes to net zero [carbon emissions], but digital technology has a central role to play,” said lead author Prof Andy Hopper from Cambridge University.
“We must stay alert to digital demand outpacing the carbon emission reductions this transition promises.”
Another co-author of the report, Prof Corinne Le Querre from the University of East Anglia, told BBC News: “To be honest, digital tech is a small fraction of your emissions compared with, say flying even once a year – but every bit of CO2 saving is significant.
"What’s more, we’re trying to prompt people to harness the power of digital to help tackle climate change.
"The way we heat our homes, for instance, is a nonsense. We occupy part of house but heat the whole thing. We can cure that by using digital technology.
“We have to make sure that the digital revolution supports the climate revolution – and we’re failing to do that at the moment.”
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Correction 10 December 2020: A previous version of this story said HD video streaming generated eight times the emissions of standard definition streams. This should have read "Ultra HD video streaming".