Commercial aviation accounts for less than 3% of global CO2 emissions. The relatively low share of global emissions is due to the fact that only a small fraction of the global population travels by air. An estimated 80% of the world population has never set foot on an airplane and 1% of the global population accounts for 50% of emissions from commercial aviation. According to ICAO forecasts, commercial aviation will grow at 4.2% per year globally from 2018 to 2038, and above global-average growth is projected in the Middle East, Africa, and the Asia/Pacific regions. Between 2000 and 2015 air travel doubled, and – prior to the COVID-19 pandemic – the number of passenger-trips was projected to grow from 4 billion to over 8 billion by 2035 (IATA 2018). Pictured below is the growth in passenger-trips up to 2018. The graph reveals a resilient growth rate of ~5% with temporary declines due to economic disruptions.
The COVID-19 pandemic caused a global downturn in air travel, but as shown in the graph below, air travel has returned to pre-pandemic levels. The growth trajectory of aviation is continuing as previously forecast (IATA, 2024).
Notwithstanding its low share of total emissions, air travel is not a low impact activity. Air travel can contribute a significant proportion of an individual’s or a company’s climate footprint. For example, the average European emits about 9 tons of CO2 per year. If a European takes one transatlantic round-trip economy flight, say from Frankfurt to New York, they will add a bit less than 1 metric tonne of CO2 to their climate footprint due to their share of the fossil fuel combusted by the aircraft. Moreover, the warming effect of CO2 is amplified when emitted at high altitudes. Some studies suggest that high-altitude emissions could amplify radiative forcing by an amount equivalent to 1.7 to 4.3 tonnes of CO2 per passenger (IPCC 1992, Lee et al., 2021, and Bramwell et al., 2023). These figures, however, are subject to high uncertainty.
Accounting for fossil fuel combustion alone, the high relative impact of air travel has led to growing calls for people to voluntarily limit their flying, and to offset emissions from the air travel they cannot avoid. Over time, use of alternative fuels and new technologies may reduce CO2 emissions from air travel, but it may be difficult to avoid the need for offsetting entirely.
Because there will be limited room for continuing to emit greenhouse gases in a net zero world, choosing low-carbon alternatives to air travel such as video conferencing or train travel should be prioritized over the purchasing of carbon credit credits. The Stockholm Environment Institute’s TR2AIL project provides practical information on air travel and strategies for avoiding it.
If flying is a necessity, then to be conservative, some travelers may wish to apply a multiplier (e.g., between 1.7 and 4.3) to determine the number of carbon credits they need to retire, to align with the evidence that high altitude aviation has added short term radiative forcing impacts.
Climate impacts from aviation
Learn how air travel contributes to climate change through CO2, Methane (CH4), Ozone (O3), and other climate forcers.
Passenger climate footprints
Passengers account for about 80% of the CO2 emissions of commercial aviation while freight accounts for the remaining 20% (ICCT, 2018). Learn about how individual passenger climate footprints are calculated, taking into account aircraft model, flight distance, seat occupancy rate, seat class, and other factors.
Don’t airlines already offset their GHG emissions?
Learn about the aviation sector’s Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) and the European Emissions Trading Scheme in regards to aviation.