Page 9 - SAFRAN DP 2021-DEFI-CLIMATIQUE-GB
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 Global CO2 related to human activities by sector in 20181
     Energy sector
Industry
Road vehicles
Land use*
4.8%
3.5%
2.1%
2.1%
0.7%
    Résidential
Other including services
37%
25.4%
14.3%
10%
   Shipping
 Aviation
Other transport
 ■ For example, engines emit water vapor which can form, depending on altitude and weather conditions, condensation trails, better known as contrails, or altitude clouds. These phenomena may cause some warming, but they only last a few days to a few weeks, as opposed to CO2, which can linger for a century! Both the cause and warming power of these non-CO2 effects depend on complex atmospheric factors, which are still difficult to measure and model.
■ In other words, the contribution of non-CO2 effects to global warming is still very difficult to quantify, and is highly uncertain. The international scientific community currently estimates the total contribution of aviation at 3.5%2 of global warming due to all human activities. Safran is fully committed to understanding these phenomena so as to better guide its research & technology efforts and identify the required technological solutions.
■ Abetterunderstandingofhowcontrailsformcould help define operational measures for flight paths to minimize their appearance.
AIRCRAFT MANUFACTURE
  ■ According to the United States Federal Aviation Administration (FAA), in 2017 the average age of airplanes withdrawn from service was 23.3 years. Given this period of intensive operation, their production and dismantling at end-of-life accounts for less than 5% of emissions during their lifetime. This percentage is significantly less than for sectors such as the automotive industry, where these activities account for up to 30% of total emissions3.
THE AIRPORT ECOSYSTEM
■ Over and above the airplanes themselves, the sector’s environmental footprint must include the entire operational ecosystem. Once again, making an accurate estimation is difficult because of the number and complexity of parameters involved and the diverse conditions across the world. The European chapter of Airport Council International (ACI) nonetheless pegs airport operations at 2 to 5% of the sector’s emissions. Then there’s the production and shipping of jet fuel, which increases emissions due to aircraft operations by about 20% – in the same ballpark as for the gas and diesel fuels used in land vehicles.
2 Source: D.Lee et.al 2020 3 Source: Mercedes study
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 ■ Aircraft engines also emit oxides of nitrogen (NOx), as well as fine particles and soot. International aviation regulations stipulate limits to these emissions, which damage human health and contribute to global warming. NOx may destroy methane, a powerful greenhouse gas, but it also creates ozone, which contributes to warming. Fine particles and soot may influence the formation of contrails or contrail cirrus, but these effects are still poorly understood.
1 Source: IEA CO2 Emissions from Fuel Combustion - SDES, from EDGAR, 2019. *Land use of ULUCF: Land use, land-use change, and forestry.





































































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