Streaming has a dirty secret. The carbon footprint produced by fans watching a month of Netflix’s top 10 global TV hits is equivalent to driving a car a hefty distance beyond Saturn. The world’s largest video-sharing site, YouTube, is responsible for emitting enough carbon dioxide annually to far .

Streaming has a dirty secret. The carbon footprint produced by fans watching a month of Netflix’s top 10 global TV hits is equivalent to driving a car a hefty distance beyond Saturn.

The world’s largest video-sharing site, YouTube, is responsible for emitting enough carbon dioxide annually to far surpass the equivalent greenhouse gas output of Glasgow, the Scottish city where world leaders will be gathering from Sunday at the Cop26 climate summit.

While much of the focus of campaigners falls on sectors that emit the most CO2 – such as aviation, automotive and food – the explosion in popularity of services from Disney+ to Netflix is raising the question of just how bad the streaming boom is for the planet.

Every activity in the chain required to stream video, from the use of huge datacentres and transmission over wifi and broadband to watching the content on a device, requires electricity – the majority of which is generated by emitting greenhouse gases.

“Strangely, environmental impact is a very young story in the streaming industry,” says Dom Robinson, the founder of Greening of Streaming, a fledgling body that aims to address the sector’s energy impact. “People talk about the bottlenecks in internet traffic caused by the growing demand for streaming and gaming services, but there is plenty of capacity, it is actually about the growing demand for power supply.”

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Netflix has estimated that one hour of streaming by one user on its platform produces “well under” 100g of carbon dioxide equivalent (CO2e) – a unit of measure that indicates carbon footprint. More specifically, the Carbon Trust says the European average is 55g to 56g of CO2e for every hour of streaming video. That is equivalent to driving about 300 metres in a car.

Netflix recently gave a rare insight into its most popular global hits by total hours viewed, a metric it said last week it intended to publish more frequently. It reported that fans clocked up more than 6bn hours watching the top 10 shows – which included Squid Game, Stranger Things, Money Heist and Bridgerton – in the first 28 days after each show was released.

This equates to about 1.13bn miles (1.8bn km) of travel in a car based on the Carbon Trust estimate – the approximate equivalent of the current distance between Earth and Saturn.

As for YouTube, a report by researchers at Bristol University based on estimates of the streaming site’s usage in 2016, calculated that watching videos on the streaming site produced CO2e of more than 11m tonnes a year, similar to a city the size of Glasgow or Frankfurt. Given YouTube had 1.4 billion users that year, and now has more than 2.4 billion users globally, the company’s carbon footprint will be significantly bigger today.

Earlier this year, Netflix announced its aim to reach net zero greenhouse gas emissions by the end of 2022. The move follows similar climate-friendly aspirations announced in recent years by the large Silicon Valley companies such as Microsoft, Apple and Facebook. In the UK, companies including BT, the BBC and Sky have promised to hit net zero by 2030.

Robinson says such strategies must involve major reductions in emissions rather than just investing in green projects if they are to achieve carbon neutrality.

“Net zero has become the new carbon tax off-setting, to be able to say: ‘This is not my problem.’ There has to be a reduction engineered within businesses, not just an accounting trick, to make a difference,” he says.

“We have created Greening of Streaming because we know there is sufficient appetite within the streaming sector to make positive changes to...