Cities around the world have seen a reduction in pollution due to the brutal halt of economic activities. Paris air particles concentration is as its lowest in 40 years. Factories have stopped working and road transportation is reduced to the minimum as people are asked to work from home when possible.
Lockdown workers use digital infrastructure to maintain their activity instead of commuting. If these digital habits are here to stay, what are their impact on the environment and especially greenhouse gas emissions compared to commuting?
A step aside: keys on greenhouse gas and climate change
A greenhouse gas (GHG) is a gas that absorbs and emits radiant energy causing the greenhouse effect. The primary greenhouse gases are water vapor (H20), carbon dioxide (CO2), methane (CH4), nitrous oxyde (N2O), and ozone (O3). Concentration of greenhouse gas in the atmosphère is linked to global average temperature. There is scientific consensus that climate change is occurring and human-made CO2 emissions is predominantly causing it.
The warming power of the different gas as well as their persistence in the atmosphere are very different. Scientists have defined an equivalent between the different greenhouse gas and CO2. This way, greenhouse gas emissions can be expressed in one common unit, i.e., metric tonnes CO2 equivalent (t CO2e). CO2 has been chosen as it represents three quarters of total greenhouse gas emissions released in the atmosphere each year.
It is always useful to have a few orders of magnitude in mind to put things in context. Common sense and experience teach you how much €1, €10 or €100 are worth or how many calories are required per day without putting on weight. However we have hardly any references in our lives for greenhouse gas emissions.
Here are a few orders of magnitude
- 50 billion t CO2e are released worldwide each year by human activities 
- France emits 460 millions t CO2e per year 
- The total emission caused by the consumption of an average individual living in France (also known as carbon footprint) is 11 t CO2e 
- A Paris New-York return flight is 2,6 t CO2e per person 
- The average family car driving 15 000 km per year releases 3,3 tCO2e 
The key for the solution to climate change rests first and foremost in decreasing the amount of emissions released into the atmosphere.
- Individual carbon footprint should reach no more than 3,9 t CO2e by 2030 and 1,5 t CO2e by 2050 to maintain temperature increase below 2°C 
Digital services and GHG emissions
In our professional and personal life, we rely on digital services and devices a lot. The Covid-19 crisis reinforced the role of digital. Without the Internet and all the digital services, we would not be able to work remotely, keep contact with loved ones, exercise, study and entertain ourselves.
Sustainability awareness in electronics is new. Although digital technology is invisible and looks “clean”, it relies on equipments that need to be built, data centers and telecom networks that need electric power, end users equipment that need to be recharged, and finally equipments that need to be taken care of at the end of their lives.
As a result, the digital sector accounts for 3-4% of world total greenhouse gas emissions . This is already twice as much as the 2% emissions of civil aviation. Furthermore, it grows at 9% per annum, compared to a 1,5% in all other sectors. Video streaming accounts for most of the traffic on the internet and GHG emissions.
The digital sector can be a leveraging tool in the ecological and energy transition provided it takes into account the same constraints as all other sectors and reduces its impact on the environment: energy and mineral resources scarcity, climate change and natural ecosystems vulnerability.
Homeworking vs. commuting
When going to the office, you may drive a car, take public transport or even ride your bike… With the exception of riding a bike or walking to the office, like the majority of human activities involving combustion, car commuting releases CO2 and other greenhouse gases into the Earth’s atmosphere contributing to the acceleration of global warming.
How does car commuting compares to a 8 hour online video conference day of an “extreme work-from-homer”? Computing the impact of digital services is a difficult task. A rough estimate is shown in the graph below using simple assumptions and data from the Shift Project data repository . Everything else being equal, this calculation shows that if you drive to work you have a much lesser GHG impact if you stay home and video conference all day unless you drive less than 0,1km in France, 1,8 km in the USA or 2,5 km in China. Estimation is based on medium resolution video stream of 480p: the higher the video resolution the higher the resulting GHG emissions.
Countries show different results because their energy mix differs. For instance, France relies on nuclear electricity, a low carbon energy for 76% of its electricity. China electricity is from coal (70%), a high carbon emission energy. This results in more emissions per each unit of electricity in China than in France.
This is a first order analysis. To deepen the analysis, second order phenomenons could be taken into account:
- The analysis assumes that the video conferencing session is between persons in the same territory and that the service uses telecom and data center infrastructure in the same territory. As Internet relies on a distributed architecture, this is only partly true.
- If working from home means more equipments (computers, phones, servers…) in households and enterprises or causes indirect negative effects such as people deciding to live further away from work and shops, results have to be revisited to take into account the so called “rebound effect”.
Digital transformation has the ability to reduce commuting impact on GHG emissions by enabling work from home. However, negative impacts can be significant if not accounted for in a proper ecological transformation strategy. If you are interested in furthering the topic of digital transformation and the environment, there are more and more research and studies available, some of which are listed in the references below [7,9].
 Climate Data Explorer. 2017. Country Greenhouse Gas Emissions. Washington, DC: World Resources Institute. http://cait.wri.org
 Tableau de bord CITEPA https://www.citepa.org/fr/politique-ges/
 L’empreinte carbone by Commissariat Général au Développement Durable Services de la donnée et des études statistiques, April 2018 https://www.statistiques.developpement-durable.gouv.fr/sites/default/files/2019-01/document-travail-n%2038-empreinte%20carbone-avril-2018.pdf
 Computation from ADEME Base Carbone https://www.basecarbone.fr/fr/basecarbone/donnees-consulter/liste-element/categorie/191
 Computation from data from ADEME Base carbone https://www.basecarbone.fr/fr/basecarbone/donnees-consulter/liste-element/categorie/151
 Computation from population growth projection of UN https://en.wikipedia.org/wiki/World_population and 2°C pathway implying a 4% yearly decrease in global emissions
 The Shift Project, Lean ICT: towards digital sobriety, 2019 https://theshiftproject.org/en/article/lean-ict-our-new-report/
 Computation from The Shift Project Digital Environmental Repository data on video (10mn 1080p resolution video uses 100Wh of electricity), country electricity mix https://theshiftproject.org/en/article/lean-ict-our-new-report/, March 2019 and data traffic from 1080p and 480p resolution videos https://www.whistleout.com/CellPhones/Guides/How-Much-Data-Does-YouTube-Use
 The enablement effect: the impact of mobile communications technologies on carbon emission reductions, GSMA and Carbon Trust, 2019 https://www.gsma.com/betterfuture/wp-content/uploads/2019/12/GSMA_Enablement_Effect.pdf