Planes are the most contaminating vehicles regarding CO2 emissions. Compared to cars, trucks, buses and trains, planes have the largest carbon contribution per km. But most indicators only consider its contribution due to the amount of burnt fossil fuels during the operation stage. However, there is much more that needs to be addressed regarding this industry’s impacts on climate change.
In this article we will describe 10 reasons why air travel contributes to climate change.
1. Fuel production
Fuels used in aviation are all petroleum-based fuels. They can be kerosene-based fuels, military-based fuels or Avgas fuels. And although all of them come from oil, many additional products are added to them including antifreeze, hydrocarbons and antioxidants. The production of all these products requires large investments and involves highly-contaminating processes like oil extraction, distillation, chemical processes, transportation and also fugitive emissions that can be lost during these stages.
2. CO2 emissions released during fuel combustion
During the operation stage, fuels are burnt in order to obtain the necessary energy that will run the plane. During the combustion, large quantities of CO2 emissions are released. The grams of CO2 emitted in a flight per km are larger than those emitted in a car, bus or truck. And 42 times higher than those emitted in Eurostar trains!
3. Other pollutants from combustion
Aircraft engines not only emit CO2 during their operation but also other pollutants like nitrogen oxides (NOx), Sulphur oxides (SOx), carbon monoxide (CO) and particulate matter (PM). Although these pollutants are not GHG themselves, they can have a warming effect because of being emitted in higher altitudes. This effects are calculated and can be explained by the radiative forcing phenomena.
4. Planes manufacturing
Modern planes are made of titanium, steel and aluminum. Some other composites materials can be included as well like polymers and carbon fiber.
Steel industry is one of the most contaminating industries regarding GHG emissions. Therefore, its constant demand for planes manufacturing is also contributing to climate change. Considering a life cycle analysis, all the GHG emissions during the materials transport, planes manufacturing and disposal at the end-of-life should be considered as contributing stages to global warming.
5. Airport infrastructure
Airport direct GHG emissions are associated to its operations: terminals, stores, use of vehicles to transport passengers and maintenance units. All these facilities consume electricity and burn fossil fuels for energy. These emissions can be reduced by insulating the buildings (reduce energy used for cooling/heating), purchasing energy from renewables and using EV vehicles.
On the other hand, indirect emissions include emissions from passenger’s vehicles and emissions from waste disposal generated within the airport.
6. Airplane contrails and cirrus clouds
Airplane contrails are visible line clouds made of water vapor emitted by planes as they elevate in the air. In the cold air, this water vapor rapidly condensates and freezes to form cirrus clouds. These clouds can remain in the sky from minutes to hours, and because they have ice crystals inside them, they are able to trap heat. Therefore, these clouds have a warming effect in the planet than can contribute more to global warming than the plane’s net CO2 emissions.
As we all know, airports require not only a lot of infrastructure but also large amounts of space. This requires wild and fertile lands to be deforested in order to create these structures. Also, many animals, plants and in some cases human communities must be displaced from their original lands. Deforestation is a main driver for climate change since it removes the main CO2 capturing source (trees). But also, urbanization means eliminating all forms of nature, including plants and microorganisms.
8. Water pollution
Ethylene-glycol is used as a deicer in planes. If this chemical is not recaptured correctly, 50-80% of it may end up in local waterways. If it reaches the water, due to the high levels of biochemical oxygen demand associated with ethylene glycol, aquatic microbial populations will consume high amounts of oxygen in order to decompose it. This could eventually cause an oxygen deficiency in the ecosystem, which can lead to many fish deaths and therefore disruptions in the carbon cycle. Indirectly, this water pollution can lead to an increase in CO2 atmospheric concentrations through inducing these animals deaths.
9. Waste generation
Waste generation in airports can be separated in the following groups:
- Municipal solid waste: food scraps, newspapers, cans, etc
- Construction and demolition: renovations or reparations within the airport.
- Green waste: Generated during landscape maintaining
- Lavatory waste: this is a type of special waste and it is generated when airplane’s lavatory tanks are emptied with hoses and pumped into a lavatory service. The tanks are after cleaned with water and disinfecting and all the waste generated in this process contains heavy chemicals and must be correctly treated.
- Spill cleanup: waste generated during the cleanup of spills
- Hazardous wastes: generated during maintenance or routine activities. Include solvents, heavy metal paints, waste sludge, batteries, etc.
All these wastes must be treated and its process or disposing also generates large amounts of CO2 that contribute to climate change.
10. Ozone production
In addition to generating CO2 and other pollutants during combustion, air travel can also lead to indirect generation of ozone (O3). The NOx emissions result in ozone production, which is also a GHG. The warming effect of this gas, according to a study, may be of the same magnitude as the effect of CO2.
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Mehta, P., Aviation waste management: An insight, International Journal of Environmental Sciences, 2015.
D.S. Lee, G. Pitari, V. Grewe, K. Gierens, J.E. Penner, A. Petzold, M.J. Prather, U. Schumann, A. Bais, T. Berntsen, D. Iachetti, L.L. Lim, R. Sausen, Transport impacts on atmosphere and climate: Aviation, Atmospheric Environment, 2010.Image by ThePixelman from Pixabay