The 5 behavioral changes that reduce your carbon impact the most

Everyone, or just about everyone, knows what behaviors to adopt to reduce their CO2 emissions. But do you know, among all these measures, which are the most effective? This file attempts to quantify the impact of the 5 actions that should be adopted as a priority to reduce our individual carbon footprint.

To begin, a few orders of magnitude. The average French person emits 7.2 tonnes[1] of CO2 per year. According to climatmundi.fr, it is accepted that the long-term sustainable level of emissions to avoid major climate change on the planet is 2 tonnes per person per year[2], i.e. 4 times less than our current emissions. This is the objective that France has set for itself by 2050. By way of comparison, in 2017, the average European emitted 8.8 tonnes; a Belgian, 10.5 tons and a German, 11.3 tons. Globally, a Qatari emitted 49.2 tons in 2017, a Kuwaiti, 25.2 tons, while an American emitted "only" 16 .2 tons.

The top 5 most effective measures

Starting assumption: 7.9 tonnes CO2/capita/year

1. Replacing the thermal car with an electric one

This is obviously the measure that has the biggest impact on our carbon footprint. Driving an electric car saves 75% of the CO2 emissions of a thermal car. The annual emissions of a thermal car being on average 2.2 t/year, the savings amount to an average of 1.65 t/year[3].

These are of course averages: about 30% of French people take a plane once a year, while more than 95% of households own a car (32 million individual cars for 28.5 million households in France in 2017[4]), with which they travel an average of 15,000 km/year.

Result by applying measure 1: 6,250 tonnes/inhabitant/year

(Note: driving 5,000 km less per year with a combustion engine car reduces emissions by 750 kg of CO2/year).

2. Avoiding a plane trip

By avoiding one plane trip per year, lasting 2 hours (intra-European trip), we reduce our emissions by around 900 kg[5] of CO2. But if you forgo a trip to Thailand, you'll save 4 tons of CO2, or up to 7 tons if you refrain from visiting Australia.

Here too, the figures vary greatly depending on the source. These differences are explained by the fact that there are 2 methods for calculating CO2 emissions related to air travel: the first establishes the quantity of CO2 according to the average consumption of the plane, the distance travelled, the average load factor and the embodied energy linked to the manufacture of the aircraft and its maintenance. The second takes into account the rate of radiative forcing[6] linked to clouds generated by aircraft. In May 2018, the journal Nature Communication stated that the clouds caused by planes arguably had a greater impact than the fuel burned by the devices.

For information, the reports of the European Environment Agency estimate individual emissions related to air travel at 285 g of CO2 per passenger and per km.

Result by applying the measures 1 & 2: 5,450 tons/year

3. Reduce your meat consumption by 50%

According to the report of the FAO (Food and Agriculture Organization of the United Nations), the production of meat requires 10 times more energy than that of vegetable products (vegetables, soya, etc.). In addition, livestock require a large area of ​​agricultural land, which accelerates deforestation. Finally, meat production has a significant impact on climate change due to the significant emission of greenhouse gases throughout the production process. These gases come from (chemical) fertilizers, livestock digestion, inefficient use of agricultural land and other secondary sources, not to mention transportation.

It is estimated that not eating meat 2 days a week is equivalent to saving 340 kg of CO2 per person per year. Not eating meat 3 days a week saves 510 kg[7] of CO2 per person per year. By replacing half of the meals containing meat with vegetarian meals, you can reduce your carbon impact by around 600 kg CO2/year. It is estimated that the annual impact of average meat consumption (> 100 g/day) amounts to 1.2 tonnes CO2/year.

Result by applying measures 1 to 3: 4,850 tonnes/year

4. Insulate your home and reduce the temperature of your heating by 1°C

If we start from the hypothesis of a house emitting 4 tonnes of CO2 per year (70% gas heating and 30% electricity) , the insulation of the roof would save 840 kg of CO2/year. The insulation of the walls generates a saving of 700 kg of CO2/year, and the insulation of the floor, up to 280 kg of CO2/year .

However, in France, many households use electricity for heating. Since the French electricity mix is ​​mainly composed of nuclear energy, insulating the roof and walls will therefore have less impact in terms of CO2 emissions than in the case of a gas-heated house. The insulation of the roof allows a saving of 30% of energy (on average 20,000 kWh/year for heating). With an energy mix emitting approximately 50 kg CO2 /MWh[8] produced, the savings made would amount to 6,000 x 0.05 = 300 kg of CO2/year.

Coupled with wall insulation, we arrive at an overall saving of 475 kg of CO2/year.

These measures, although stimulated to varying degrees by the government, are often more difficult to implement given the investment cost they involve. On the other hand, reducing the ambient temperature does not require any investment. ambient temperature can reduce emissions by 75 kg to 300 kg of CO2 per year depending on the energy source used. Given that 47% of French people heat with electricity, 23% with gas, and the remaining 30% with oil or wood, we will assume a saving of 250 kg of CO2 per year.

Result by applying measures 1 to 4: 4.125 tonnes/year

5. Buy clothes in organic and local cotton

Studies estimate that the textile industry is responsible for 3% to 10% of global CO2 emissions. The best t-shirt is of course the one you don't don't buy. Because the manufacture of cotton clothing requires a very energy-intensive process: a white cotton men's T-shirt weighing 155 g emitted 6.5 kg of CO2. And we are not talking about the 2,500 liters of water, as well as the pesticides, insecticides and dyes loaded with heavy metals that its manufacture required...An equivalent t-shirt made with renewable energy and organic cotton does not emit than 0.67 kg of CO2. Ten times less. And each French person buys an average of 9.2 kg of clothing per year.

By buying only organic cotton clothes, he could save 340 kg of CO2 per year.

Result by applying measures 1 to 5: 3.785 tonnes/year

The implementation of these 5 measures is obviously difficult to achieve in a short period of time. It is expected that for their application, a delay of 10 years is necessary. In addition, these 5 measures do not make it possible to reach the recommended threshold of 2 tons/capita/year, but they nevertheless contribute to reducing its CO2 footprint by almost half.

We have selected here only 5 measures among those which seem to us to have the greatest impact on our carbon dioxide emissions. The figures quoted do not detract from the interest of eating organic and local, of aiming for zero waste, to keep your mobile phone for one more year, to ride an electric bike or to install a water tank, but they give orders of magnitude, which will undoubtedly allow some of you to better prioritize these different measures. .

[1] Source: https://ec.europa.eu/eurostat. The figures are expressed in CO2 equivalent units, and include all greenhouse gas emissions contained in the “Kyoto basket” (CO2, CH4, N2O, fluorinated gases and SF6). The emission of an average French person varies according to the sources: the figure differs depending on whether we are talking about individual CO2 emissions (CO2 emitted in the country) or the carbon impact which includes indirect emissions (imported products). The Planetoscope.fr site speaks of 11.9 tons of CO2/capita/year.[2] The figures also vary according to the methodology applied: depending on whether one calculates the total allowable CO2 emissions, related to the number of inhabitants of the planet, or whether one takes into account the fact that several countries already emit significantly less than the threshold of 2 t/capita/year, which would allow industrialized countries to emit up to 4.5 t/capita/year.[3] The emissions of an electric vehicle are estimated at 40 g CO2/km, compared to an average of 160 g for a thermal vehicle (taking into account the undervaluations of the actual figures). Changing the propulsion mode therefore saves 75% of the emissions of an internal combustion engine.[4] http://www.economiematin.fr/news-demographie-la-taille-moyenne-d-un-foyer-francais-est-de-2-2-personnes-seulement[5] http://calculateurco2.org/ airplane/?lang=en.[6] Radiative forcing expresses the man-made imbalance between incoming energy (solar radiation) and outgoing energy from the atmosphere. The percentage of anthropogenic radiative forcing related to the aviation sector is estimated at 4%.[7] EVA, www.vegetarisme.be[8] http://electricitymap.tmrow.co