What is a carbon footprint? What impact do we have on it? And it on us? We will focus on its link with greenhouse gases, the climate and how we calculate it.
The carbon footprint measures human activity's impact on greenhouse gases (GES). In particular, carbon dioxide, or CO2, emitted by burning fossil fuels (coal, petrol) to produce and meet all our consumption needs.
First off, the greenhouse effect: it is a natural process. This sustains a temperature enabling life on earth. It would be -18 °C on average on our planet without it!
It comes in the form of different layers of gas: moisture, carbon dioxide, methane or nitrous oxide. These are the famous greenhouse gases.
They absorb a part of the sun's energy and slow down the rate of heat loss, just like in a... greenhouse ! It subsequently gets warmer on planet earth the higher the concentration of these gases in the atmosphere.
This fragile balance is disrupted by humans' industrial activity, emitting some of these gases in casts amounts. The concentrations of carbon dioxide or CO2, in particular, have increased 47 % since the 18th century. It is thought to be responsible for 65% of this additional man-made greenhouse effect. These increases in gas emissions mechanically causes global warming.
The planet's temperature has already risen, on average, by 1°C in the 20th century. By 2040, it should continue to increase by 0.8 °C. According to the last report by the UN's Intergovernmental Panel on Climate Change (IPCC), the average temperature on earth could still evolve from 2.6 to 4.8 °C during the 21st century.
To better understand, Dominique Bourg, a climate change philosopher, compares the situation to that of the last ice age. "Barring accidental events, when we go from an ice age to an interglacial age, the average temperature evolves by 1°C every 1000 years. An increase we have experienced in only 40 years, from the 1970s until today!".
This is why in 2015, the Paris agreement, signed by 222 countries at COP21, planned to reduce their greenhouse gas emissions to sustain the temperature at 2 °C compared to the pre-industrial age until 2100. It is an ambitious target. However, it is not enough to prevent wide-scale disruption to our ecosystem, and some specialists expect there to be +2°C as soon as 2040.
As Dominique Bourg reminds us, "a variation in the average temperature of the whole planet is not comparable with a change in the weather. . +2°C, on average, on earth will lead to temperatures that could reach close to 50°C in summer in France".
It is therefore not "just" a few extra degrees, allowing us to spend nicer summers in the North of France. The temperature increases will, in reality, be much higher, going so far as drastically changing life conditions on earth, and even making them unbearable in some places.
Wildfires in Australia and California,
Heatwaves in Canada,
Ocean acidification,
Coastal flooding in Japan,
108-day record without a negative temperature at the Pic du Midi (mountain in the French Pyrenees),
Heavy rainfall in Germany and Belgium,
A free fall in biodiversity: 60 % decline in species of vertebrates within 44 years…
This climate change will, in all likelyhood, lead to the migration of populations. It will intensify air pollution, having a direct impact on everyone's health.
Skiing seems to be the sport the most directly threatened by global warming, but the spectre is in actual fact much broader. The rise in ocean levels and the erosion of beaches will, for example, make surfing much more complicated. A sport as popular and easy to do as running immediately becomes a great deal harder when it involves running at over 30°C.
And what about ice climbing on glaciers? The Sea of Ice (France) is losing up to 30 m a year! The impact of global warming on biodiversity also has consequences on our sporting habits: hiking or even scuba diving will be a lot less appealing without animals and plant life variety.
By drawing up a list of the consequences of global warming, we better understand why it is imperative to measure the impact of human activity on the concentration of these gases to the greenhouse effect, and, in particular, CO2.
This assessment lets us measure the most polluting activities, and, potentially reduce them. It is also thanks to these assessments that countries and companies will be able to know if they meet the ambitious reduction targets that they set themselves.
The responsibility of this breakdown also falls to each and everyone one of us. Industrial activity, in actual fact, reflects our needs and way of consumption. It is also possible for us to individually calculate our carbon footprint to determine the household areas having the largest impact on GES emissions.
People's average carbon emissions rate is grouped together into the 3 main categories, which we will take into account in the calculation. It is firstly housing, (with 27 %), followed by transport, (25 %), and lastly food (19 %). We divide the remainder of an individual's carbon impact between goods and services, health, education, public services, equipment and clothing.
There are several free calculators for finding out what your ecological footprint is, such as the "Foot print calculator" or "Nos gestes climats" (Our climate actions) by the French Government's Environmental Transition Agency (ADEME).
A carbon footprint is expressed as weight, generally, in kg or tons of CO2 emitted.
Good to know: we calculate the carbon impact of an activity, a product, a company, a territory or a person.
The idea is to add up the different life stages of these entities, likely to emit CO2, such as the energy consumption, resources, transport, purchases, or even eating habits for physical people.
In France, according to the ADEME's calculator, a person's average CO2 emissions per year is 11 tons.The objective would be to reduce this carbon footprint by 2 tons per French person.
It is possible to change your impact the moment everyone of us reduces the use of their car, taking flights, their red meat consumption, or renew their equipment if necessary. To reach 2 tons of CO2 per person, we have to go much further: thermal renovation of buildings, industry, agriculture and energy production that pollutes less…
To calculate a product's carbon footprint, we have to observe its entire life cycle:
- the birth of the concept
- production of raw materials,
- product manufacturing,
- transport,
- distribution,
- use,
- end of life.
If we take the example of a T-shirt's life cycle, you will have to take into account water consumption to grow the cotton, the energy required for spinning, weaving, dyeing the cotton and assembling the fabric, etc. You also have to consider the channel it uses during the course of its use: incineration, recycling, etc.
Emilie points out that "depending on the products, there can be numerous very specific sub-steps. What is hard is getting the data from tiers 2 and 3 suppliers". In other words, from the manufacturer's own subcontractors. This is why the ADEME suggests different scenarios to get a clearer picture, allowing companies to formulate hypotheses about their products' CO2 emissions.
Emilie also reminds us that "the challenge is not to have the most accurate possible data, but actually about determining the activities that emit the most CO2 to then conceive of solutions that reduce these". The calculation step is therefore crucial.
The same principle applies to companies as it does to products. E. Aubry specifies: "ideally, we look at all the company's activities: whether they be direct CO2 emissions (or scope 1), energy purchases (or scope 2) and indirect waste (those of a supplier for example, a customer coming to a store, etc., which we call scope 3)".
These 3 scopes are the limits upon which companies base themselves to define the calculation of their emissions.
If the ADEME strongly encourages , companies are currently under no obligation to calculate scope 3 and reduce it. Even though these indirect emissions turn out, in many cases, to be an activity's most important CO2 tonnage scope. Conversely, the companies willing to put a figure on it commit to the Science Based Target initiative, supported, in particular, by the United Nations, to limit their impact to 2°C.
To better understand the activities included in the calculation, let's take a random example… DECATHLON.Here are parts of its activity (all scopes included)the company reports CO2 emissions for:
- Manufacturing products
- Transporting these products
- Delivery to the customer when it is e-commerce
- Customers' journeys
- Employees' journeys warehouses and stores: waste, energy, construction.
If some data can actually be collected, a lot will be based on hypotheses. We can, for example, make a forecast concerning customer journeys using a survey of a representative panel.
There are standard international calculation methods like the "Greenhouse gas protocol" which let you calculate emissions, in particular, from sites, and tools such as Resource advisor, Metrio, Pace, Glimpact, etc.
These tools allow you, for instance, convert a unit - kWh, L, ton kg, etc. — into a ton of CO2 emitted by multiplying it by an emissions' factor. It will be different depending on the country concerned: China's emission factor, which uses coal power, will be higher than France's, which uses nuclear power. By the end of the calculation, litres of petrol consumed by lorries on the road and the kWh of energy are converted into tons of CO2.
Once the principal source of CO2 emissions is established, we can then go about reducing this impact.
If we go back to the 3 main areas of our carbon footprint, what can you put in place?
- Housing: to consume less energy and less water, we can opt for energy-saving household appliances when it is not repairable and it becomes necessary to replace it. You can also reduce your electricity consumption thanks to LED light bulbs, unplugging your appliances after use or lowering the central heating a bit. You can even go further by renovating your home.
- Transport: the personal car with a combustion engine is an important source of pollution. You can use a bike, especially for journeys under 5 km, or public transport: train, metro, bus, car sharing. For big trips, it is preferable to opt for the train instead of the plane. And then you can revise your flight travel destinations: go for longer, but less often.
- Diet: what generates lots of nitrous oxide and therefore lots of GES is the production of animal-based products, chiefly red meat. You can reduce your consumption. Eating local and seasonal produce will also help to reduce transport used for these consumer products.
Either as a private individual or a company, you can also opt for making "green" financial investments. The idea is to buy financial products that divest from supporting, for example, fossil fuel-based products.
For products
To reduce products' carbon impact, here are the reduction action plans with a strong potential:
– a longer life span by opting for second-hand rather than buying or producing something new. Put more emphasis on reselling second-hand,
– more recycled products,
– improve techniques for producing materials,
– use renewable energies in manufacturing and prohibit resorting to coal,
– manufacture products that are less energy-intensive.
For companies
In addition to what is put in place on their products, companies can also take action by:
– increasing their e-commerce sales share to avoid customer journeys to the store. So long as the energy required by data centres and home delivery have a lower carbon impact... not a simple equation :/
– or even build fewer new sites, opting to reuse existing sites.
Offset your CO2 footprint means counteracting your own carbon impact by investing in carbon sequestration projects working to reduce overall emissions. This may translate in the following ways:
- finance reforestation "" and sustainable forest management projects,
- support regenerative agricultural practices,
invest in start-ups working in innovative concepts helping to capture CO2,
- finance the development of carbon wells..
The concept: The concept: give money to an organisation in charge of planting trees on our behalf if we have taken too many flights this summer.Let's be honest, the method essentially consists of stop feeling guilty about not changing our habits. The practice goes so far as simply purchasing carbon credits without knowing how they will be used. It then becomes necessary to analyse the certification of these credits.
Some companies, by the way, would appear to be putting big budgets into supporting reforestation, deploying solar ovens or even carbon capture and storage in the ground. It is commendable, but according to Emilie Aubry, "the concept of offsetting is misleading. Offsetting doesn't exist. In fact, as a company, we contribute. Favouring offsetting over reduction is in actual fact buying a right to pollute. You sequester when unable to reduce emissions".
Let's evaluate the (carbon) situation
It is, therefore, well and truly urgent to reduce your emissions rather than offsetting them. In any case, this is what the "Net zero initiative" encourages, as supported by the ADEME and Carbone 4 consultancy firm. It has also set this goal as a priority, around which determined companies have come together and committed to carbon neutrality.
