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The impact of flying on climate change
It is now widely known that the global climate is changing rapidly due to human emissions of greenhouse gasses, and that little time is left to keep global temperature rise within manageable levels. Most people probably also know that aviation has an enormous impact on climate change, and that as a society we therefore need to strongly reduce aviation, but the urgency of this is not widely appreciated. As a reminder of this critical issue, and as a tool for convincing those who may not be fully convinced by its severity, the Sustainability Committee of ISEB and IPMB has created this short list with reasons why we all should limit how much we fly:
Flying has an enormous impact on climate change. In 2018, globally flying accounted for 2.65% of all CO2 emissions. In addition, aviation contributes to global warming with emission of other greenhouse gasses (GHG) and processes such as contrail formation. At the beginning of 2020 the remaining carbon budget to stay within 1.5°C of warming compared to the pre-industrial era was 400 billion tons of CO2, i.e., about 1.5 tons of CO2 per year per person until 2050. One return flight between Zurich and New York has a climate impact of 3.6 t of CO2 equivalent per passenger (economy class).
The number of kilometres flown is continuously increasing. Between 1960 and 2018, the amount of flown passenger kilometres per year increased 75 times, to 8269 billion kilometres per year. The COVID-19 pandemic caused a drastic decrease in air travel, with about 55% less passengers in 2020-2021. However, the aviation industry predicts a return to pre-COVID conditions in a few years.
Figure 1: Total passenger kilometres flown. (Source )
The global distribution of flying is deeply unfair. While Europe and North America together contain circa 17% of the world’s population, together they accounted for 49% of all flown passenger kilometres in 2019. Moreover, it was estimated that every year only about 11% of the world population take a flight, and that the 1% most frequent flyers are responsible for 50% of emissions from passengers’ commercial aviation. This means that by flying this much, people in richer countries such as Switzerland are disproportionally exacerbating climate change, whose effects will likely be most keenly felt by those in poorer regions.
Flying emits far more greenhouse gas than travelling by bus or by train. A trip from Zurich to Vienna by plane emits six times as much greenhouse gas as traveling by train does. Flying to Paris emits more than ten times as much (see Figure 2).
Figure 2: Greenhouse gas emissions of different modes of transport (calculated taking into account the following occupancy rates: plane: 75%, car: 1 person, bus: 44%, train: 30-55%) (Data source / graph source)
