2.3. The ICT sector’s carbon footprint – variations in estimates

There is inherent complexity and uncertainty when calculating the footprint of ICT. As a result, estimating the carbon emissions of ICT has, historically, proven quite challenging. Previous estimations of ICT’s carbon and energy footprint vary substantially. This variation between footprint estimations results from differences in the scope, methodology and boundary definition for the ICT sector, that ranges substantially between previous studies (Freitag et al., 2020).

Firstly, defining the boundary of the ICT sector can impact the results of calculation. The ICT sector, unlike other more finite sectors is more difficult to define in terms of its boundary. The ICT sector actually consists of a variety of very different sub-sectors (e.g. ICT equipment manufacturing, component manufacturing, data centre operations, telecommunication network operations, software, IT services). Whereas, for example, global steel production has a well-defined boundary with a finite number of manufacturing operations/plants and value chain that covers its supply. Additionally, many steel companies report their emissions data, via the World Steel Association, enabling more accurate determination of the steel industry’s total footprint. This level of transparency has not yet been achieved within the ICT sector.

Therefore, defining ICT’s sector boundary is potentially more complex than other industries. The internet refers to a global integrated network of networks connecting millions of different users and devices, that are each capable of sending, receiving and processing data all of the time. Thus, it is harder to agree on a universal definition of its boundary. As such, previous studies may use differing definitions. Important considerations include the scope of technologies used for the calculation, such as the inclusion of TVs or types of IoT devices. Also, the inclusion of embodied emissions of ICT hardware and equipment is another key consideration. Studies vary depending on their allocation of these full lifecycle emissions. Namely, whether their estimation accounts for end-of-life emissions as well as upstream production and material extraction emissions (Freitag et al., 2020). The carbon footprint of ICT services is also dependent on the electricity mix, that varies between different countries. Thus, whether the calculation accounts for renewable energy portion of electricity used will significantly affect the estimation. Secondly, as a result of the ICT sector’s complexity, the methods and assumptions used for carbon footprint calculations differ between studies. Some adopt a topdown approach of global ICT energy estimates. This approach relies on the extrapolation of historic estimates of carbon intensity and estimating future trends from model projections. Alternatively, systematic bottom-up approaches have been applied, using real-world data to estimate the footprint of each ICT sector component such as global data centre servers (Masanet, 2020a) or network operator emissions (Malmodin & Lundén, 2018a; Malmodin 2020a). These tend to produce more robust estimations as they are based on detailed data points that can be scaled-up to provide a global figure.

In addition, some studies are actually scenario analyses – modelling what the impact for energy and emissions would be, based on differing growth assumptions. Then, these scenarios are often oversimplified and reported in the media to the public as either concrete projections or as facts, when they were simply answering a series of “what if” scenario questions.

Some studies have produced erroneous estimates by relying on previously published estimates of the ICT sector emissions (that may themselves be five to 10 years old), then extrapolating them to the current date using historical growth projections (which may also be five to 10 years old). Because the technology changes so rapidly it is not reliable to simply use extrapolations from historic data. The more robust estimates recalculate the emissions by using the latest available industry data: for data centres using industry data on the number of servers and server energy consumption; for telecoms networks using actual reported emissions from network operators; and for end-user devices using industry data on numbers of devices sold and the energy consumption of different device categories.

An additional complexity is that the emissions intensity of electricity generation varies over time and by location, and these variations are big enough to matter (more than an order of magnitude in some cases). It is therefore difficult to compare independent estimates of ICT emissions directly without supporting information on the energy intensity of ICT technology and the emissions intensity of electricity generation.