Globally, the aviation industry is responsible for 2% of annual CO2 emissions, according to the International Air Transport Association (IATA). Fuel consumption releases water vapor and nitrous oxide, among other greenhouse gases (GHG).
10% of ground and low altitude emissions pollute the same as the remaining 90% of the flight, which place at an altitude above 3,000 feet. For example, from the gate to the runway, an aircraft can consume an average of 250 liters of kerosene.
At busy airports such as Heathrow, aircraft emissions on the ground generated more than half of the nitrogen oxide detected. It is therefore necessary to introduce sustainable alternatives to reduce emissions on the ground.
1. Offsetting emissions
For many years, airlines have been offering customers the possibility to offset their emissions by paying a certain amount either at booking or check-in time. The money is then invested in projects such as protecting forests or growing natural reserves. Though data shows that many people are concerned or feel guilty about their trips, very few take any action.
There’s a big disconnect between passengers saying ‘yes, we want carbon offsetting’ and their response when prompted to take action. 99% will quietly say ‘no thank you we won’t do it’.Michael O’Leary, Ryanair’s CEO
CNN reports that according to the Civil Aviation Authority’s 2021 consumer research tracking study, 41% of respondents agree or strongly agree that they think about the impact of flying on the environment when considering traveling by air. 39% agree or strongly agree that they would pay more for flight tickets to reduce the environmental and/or noise impact of flying.
In November 2021, Ryanair’s CEO Michael O’Leary said that “the uptake last year was 1%,” CNN reported. O’Leary said there’s a “big disconnect between passengers on a customer survey going ‘yes, we want carbon offsetting, we want to do this’ and then ask them will you voluntarily offset, and 99% say ‘no thank you we won’t do it’ — so it’s a big challenge.” A study published by the Air Transport Action Group (ATAG) of 44 airlines found that “the typical current take-up of voluntary offsetting by passengers was 1-3%.”
2. CO2 calculator for air travel
The International Civil Aviation Organization (ICAO) has developed a tool for calculating carbon dioxide emissions from air travel. Google also offers a Google Flights calculator, though the way it calculates emissions changed causing some misapprehensions among consumers, the BBC reported. Flights appear to have much less impact on the environment than before.
According to the BBC, Google decided to take a key driver of global warming out of its online carbon flight calculator. “Google has airbrushed a huge chunk of the aviation industry’s climate impacts from its pages” Dr Doug Parr, chief scientist of Greenpeace, told BBC. The company said it made the change following consultations with its “industry partners”.
According to ICAO’s calculator, a plane trip from Hamburg to Munich would generate approximately 61 kilograms of CO2 per passenger and an approximate fuel consumption of 5000 liters of kerosene.
However, a factor called radiative forcing must also be taken into account. Radiative forcing is due to the condensation trails (contrails) that aircraft leave in the air and that block the radiation that should escape into space, increasing global warming.
Currently, radiative forcing means that CO2 pollution from airplanes has to be multiplied by 1.9, which almost doubles emissions to 122 kilograms of CO2 per passenger for the Hamburg – Munich route. The same journey by train would produce 20 kilograms of CO2 per passenger, about 6 times less. The emissions of a car are closer to those of an airplane than those of a train.
Ships pollute much more than airplanes, so their uses are displaced to routes where there is no alternative either by load capacity or by number of passengers transported.
This tool is not the only one that ICAO has published to raise awareness of climate change. Other tools include the fuel savings calculator, which allows airlines to design their air operations to reduce carbon dioxide emissions.