Climate emissions of videostreaming

Table 1: Estimated carbon intensity of one hour of streaming.

There are varying estimates of the carbon footprint of streaming video, as shown in Table 1. 2019 estimates from The Shift Project [48] put the emissions at 394 g CO2e per viewing hour, a correction to a prior study in which they had mistakenly claimed streaming video was equivalent to driving over 10 km [26]. However, the Shift Project’s estimates are not considered reliable [26], with even a recent study sponsored by Netflix [45] estimating a footprint of just 55 g CO2e, 1/8th as much. The primary factors driving this low footprint are the technology trends described above - more efficient video codecs, the shift to cloud encoding from edge decoding, and the rapid adoption of renewable energy by cloud operators. The Netflix study finds that user devices still account for a large fraction (>50%) of overall energy usage in the streaming ecosystem. This suggests that major improvements are still possible, especially in reducing the environmental impact of devices. But even Netflix’s footprint can be further reduced through the streaming optimized devices described earlier, as the International Energy Agency (IEA) finds that 55 g CO2e/hr is still far too high and a more realistic number is 36 g CO2e/hr, which they compare as similar to boiling a kettle at 35 g CO2/hr [26]. The IEA goes on to show that if streaming is done in countries where energy is low-carbon, such as France, then the carbon footprint is only 4g CO2e/hr, a figure that serves to show the potential future benefits worldwide of streaming from carbon-free energy in data centers and using low-carbon streaming devices.

We understand that the energy consumption of data centres and networks currently represents about 2-3% of global electricity consumption, driving 0.6% of total GHG emissions.

Streaming has a relatively small energy and carbon impact as an entertainment activity, especially compared to other daily activities; one hour of video streaming (use-phase) emits about as much as microwaving four bags of popcorn, or three boils of an electric kettle in the UK

one hour of video streaming emits less carbon than driving a petrol car 300 metres, i.e. approximately 23 seconds of driving on a residential street

the conservative European average emissions attributable to video streaming are 55 gCO2e per device hour

The European average footprint estimated in this white paper is approximately 55gCO2e per hour of video streaming for the conventional allocation approach.

The marginal impact over fixed network as resolution and bitrate increase, is relatively small, where the transmission emissions grow from just under 1gCO2e/hour to just over 1gCO2e/hour between SD and 4K. This represents an increase of 26% in aggregated core and access transmission emissions from SD up to 4K.

For users, the most effective way to reduce their carbon impact of streaming depends on the network being used. Over a fixed network, using a more energy efficient or smaller viewing device has a far greater impact than changing video quality, particularly as enduser devices dominate the total emissions from streaming over fixed network. In fact, this analysis demonstrates that changing video quality while streaming over a fixed network has a negligible short-term impact. For a typical user streaming over a mobile network with a smartphone, emissions are small even at higher bitrates, estimated at less than 5gCO2e/hour in this scenario using the power model approach.

As video streaming consumption increases in the future there may well be a rebound effect of increased energy use and carbon impact, potentially to the point where efficiency gains in network transmission and end-user devices are outweighed by the increased consumption of streamed video content. This highlights the importance of the continued uptake of renewable electricity to power transmission networks, so that increased network energy consumption does not translate directly to increased emissions.