Simon Baker (Program Director)

The IT industry hasn’t been a major target of climate campaigners, and there are lots of good reasons why — its major players are poster children for carbon neutrality. Most of the big West Coast companies accepted straight off the dangers of climate change, the connection with emissions and their responsibility to reduce their own.

Facebook and Apple score particularly highly in most of the assessments of power sourcing from renewable energy, while Google is the world’s biggest corporate purchaser of green power. Microsoft recently made a pledge to remove all the carbon it has ever been responsible for emitting. The International Energy Agency (IEA) calculates that the overall ICT industry is responsible for half the global purchasing of renewable energy.

It would be misleading to say the issue is under control, however. A number of recent studies show that total emissions from the sector are not only growing fast, but are about to grow even faster. The reason is simple: burgeoning growth.

The Power-Budget Equation

If we start at the beginning and look at total power consumption by IT, including client devices, servers and the networks that connect them, in total they take up about 4% of global energy consumption. The client device side consumes less than the service side of servers and transmission, according to a study by the Paris-based researcher the Shift Project (based on 2017, and quoting researchers Andrae and Edler). In contrast, aviation, the subject of Greta Thunberg’s flight shaming, is commonly estimated to account for around 2.0%–2.5% of emissions.

Server Installed Base Shipments

Streaming Takes More Power Than Watching TV

Greta is not yet shaming us into cutting down on putting videos on YouTube or watching Netflix on account of the carbon footprint they cause, but should she be?

Rapid increases in data traffic and more power-hungry ways of consumption will quickly push up IT electricity consumption.

Central to this growth is video streaming, which has a CAGR of 46%, according to Cisco, with IP video traffic projected to make up 82% of all IP traffic in 2022. Sandvine, another industry source of statistics, says that in 2019 video equated to 60% of the downstream traffic on the internet.

Video streaming interrogates a server individually, so taking more power than television broadcasting, which continues meanwhile in parallel. The Shift Project says the carbon footprint of global video streaming is as big as the total emissions produced by Spain.

More viewing is taking place over mobile networks, whose signal propagation takes more power than relay through fixed-line networks. Again, according to Cisco, mobile data traffic is growing almost twice as fast as fixed, while Ericsson in its latest Mobility Report in November forecast that mobile data traffic would quadruple globally by 2025.

There are a few trends towards the power economy; viewing on small screen mobile devices, for instance, takes much less electricity than on big television screens, but on the other hand the move towards 4K definition will increase both the amount of data used in the signal and the power consumption of the screen. The Natural Resources Defense Council in the US believes that 4K screens typically use 30% more power than HDTV screens.

Trajectory of Growth Difficult to Pin Down

There is a good deal of uncertainty about how fast the upwards trajectory of total power consumption from the IT sector is going to be. One researcher who has looked in depth at the question is Anders Andrae, whose data was used by Shift for the overall industry picture quoted earlier.

In September 2018, in an article based on his research, the science journal Nature quoted his “expected case” scenario of this total rising to an alarming 21% of global total electricity consumption by 2030, with the tempo still accelerating at the end of the forecast. In his “best case” scenario, which involves a lot more implementation of power saving, the percentage was 8%.

These figures are controversial. In recent years datacentre power consumption has not increased substantially, as the new hyperscale datacentres that have come into use are much more efficient; Google has held down total power despite much higher data throughput. Hyperscale centres now make up close to half of all datacentre usage, says the IEA.

What is not clear is how far this rate of efficiency gain can continue.

Andrae’s studies were based on figures dating from 2013. In updating his figures, the Shift Project said in 2019 that he had underestimated the annual rate of power consumption, which it believes was around 9%. It sees a similar rate of increase through to 2025.

Traffic Grows in Places Renewables Do Not Figure

Another reason to believe that the emissions from data traffic growth will rise fast is territoriality. Data flows are getting much bigger in places that rely heavily on fossil fuel electricity generation, notably coal.

China has about 7% of global datacentres. Cisco says that Chinese mobile data traffic grew 180% in 2017 alone. A recent study by Greenpeace and the North China Electric Power University suggested that China’s datacentre power use would grow by two-thirds over the next five years, to a level equal to total power consumption in Australia.

Though the big Chinese internet players such as Tencent, Baidu and Alibaba do comment on their environmental impacts, they are scant on statistics on the level of renewables usage — there just is not as yet the climate concern shown by their big US West Coast counterparts. The Greenpeace report said that three-quarters of current datacentre power in China is derived from coal. China has a lot of renewable power, but most of it is in the Gobi and in the west of the country, whereas most of the datacentres are near the east coast, and are currently often not able to tap into much renewable energy.

The Shift Project calculated from this that while a Chinese person on average consumes about 12% of the average digital usage in the US, the emissions footprint in China for the same data volume would be 2.5 times as high.

I am not focusing here on the network side of the equation, but in brief the same factors play out as with servers — more data traffic will mean more power consumption. Most European telcos are moving towards renewables, but in many other countries they are not, or do not have access to green energy.

Should Consumers Be Made More Aware?

Greta Thunberg has yet to shame us on carbon emissions from our internet use, and indeed is a user of social media herself.

Though it is commonplace in the IT industry that servers take a lot of power, it is not very well known among consumers. The Shift Project calculated that watching Netflix for two hours would be equivalent to 6.4kg of emissions, about the same as driving a car for 24km. A 10-hour-a-week Netflix habit would mean 1.6 tonnes of CO2 a year, about the same as flying one-way from London to, appropriately, Los Angeles.

These remain complex and individual calculations. Netflix, which in 2015 claimed, improbably, that watching its streaming services caused fewer emissions than reading, is not in some ways a good example; Amazon Web Services, which manages Netflix’s playout, “pushes out” a lot of the Netflix catalogue to forward distribution servers installed at local ISPs, so transmission levels are reduced, and the power budget linked to that of the ISP.

However, it is not difficult to conceive of a system emerging where consumers will increasingly be presented with assessments of how much carbon emissions their viewing will produce, just as the relative CO2 emissions levels of different flight options may be shown on comparison sites, and producers of many consumer electronics devices already prominently show their power consumption levels.

In the history of climate change and our reaction to it, 2019 will probably go down as the year a lot more companies, at least in many developed countries, faced with mounting evidence of the speed of climate change, decided to take that message onboard and do their part to measure what emissions they are responsible for, and to mitigate and offset them.

Making clear to consumers the carbon impact of the internet and how it is being mitigated has only just begun.

A couple of hints: It is most efficient, in energy terms, to watch video on a small device on WiFi from a fixed-line connection. Avoid choosing high-definition options, for video or when taking pictures. And perhaps upload a few less.


If you want to read more…


The Tech for Sustainability and Social Impact Group, set up in IDC EMEA last year, helps IT companies and end users in their attempts to use technology to make their businesses more sustainable. Please contact Marta Muñoz for more information, or head over to and drop your details in the form on the top right.