This article is an excerpt from a report commissioned by Greens/EFA and conducted by CE Delft called “Carbon footprint of unwanted date use by smartphones”. Read the full article here.

Recently, the European Commission has published its strategy on data (EC, 2020). This strategy mainly focuses on the opportunities digital technologies and data sharing can create and the privacy risks associated with it. Smartphone apps collect more user data (also called tracking) than most consumers prefer. Besides privacy risks, the collection of user data also results in a carbon footprint as sending this user data to third parties and showing personalised advertisements consumes network data.

When the user tracking is unwanted, also the consumption of network data for tracking is unwanted. Ideally, rules for smartphone companies to limit unwanted user tracking would also reduce this unwanted data use and the accompanying carbon footprint. So far, however, it is unknown what the carbon footprint of this unwanted data use is and what the potential carbon footprint reduction of limiting user tracking is. Therefore, the Green Party in the European Parliament has asked CE Delft to determine the carbon footprint of unwanted data-use by
smartphone apps.

In this study we define the unwanted data-use by smartphone apps as the network data (both cellular and Wi-Fi) used to transfer the data collected by third-party advertisement and tracking services (ATS) in smartphone apps to the third-party servers. As approximately 60% of the consumers indicate that they would turn off third-party tracking, 60% of the network data used by ATS is qualified as unwanted.

To determine the carbon footprint of unwanted data-use we have combined the information on the amount of network data used by ATS with the electricity consumption of the data network and the carbon footprint of electricity production, as shown in Figure 1.

As the information on data-use by advertisement and tracking services is limited, the technology is developing at a fast rate and the electricity consumption of data networks is uncertain, this study only provides a first estimate of the carbon footprint of unwanted data-use by advertisement and tracking services. To arrive at a more specific and certain carbon footprint, more research is needed.

We estimate that the total carbon footprint of data-use by tracker and advertisement services in apps on European smartphones is between 5 and 14 Mt CO2-eq. per year. When 60% of the consumers label these services as undesirable, the carbon footprint of the unwanted data-use by tracker and advertisement services on European smartphones is estimated to be between 3 Mt and 8 Mt CO2-eq. per year.

Enabling users to turn off these tracking activities could then prevent between 3 and 8 Mt of CO2 emissions per year, which equals the CO2 emissions of 0.7 to 1.8 1,000 MW coal-fired powerplants, the CO2 emissions of European cities such as Turin or Lisbon or the CO2 emissions of 370 to 950 thousand European citizens.

To compensate for 3 to 8 Mt CO2 emissions, 160 to 410 million trees need to grow for one a year or between 60 and 150 million PV panels need to be installed to replace the average European electricity production.

Editors Note

We are pleased that more studies are tackling the cost of digital products and services. Investigating the emissions from unwanted data like ads can help with policymaking and technology decisions as they intersect not only with the climate impacts and a warming planet but with consumer protection and ad tech reform.

We note, however, that the figure used in this study for 4G data transfer (i.e. sending data over 4G, which is more energy-intensive than other forms of transfer) is at the upper end of the numbers we are familiar with. This means the total figure reported here may be an overestimate of around 50%.

We, therefore, think it is safer to lean towards a lower range of about 3 – 8 megatonnes when talking about the emissions from unwanted data on mobile. This revised figure is still very worthy of discussion, and since many people have difficulty picturing a megatonne of carbon, the argument doesn’t lose much by using a more conservative figure. We think the central claim of this report—that 1/5 to 1/6 of all traffic sent on mobile is essentially wasted ad tracking— is still worth discussing, and represents societal costs of ad-tracking being shifted onto end users.