Cost and emissions pathways towards net-zero climate impacts in aviation

Aviation emissions are not on a trajectory consistent with Paris Climate Agreement goals. We evaluate the extent to which fuel pathways—synthetic fuels from biomass, synthetic fuels from green hydrogen and atmospheric CO 2 , and the direct use of green liquid hydrogen—could lead aviation towards net-zero climate impacts. Together with continued efficiency gains and contrail avoidance, but without offsets, such an energy transition could reduce lifecycle aviation CO 2 emissions by 89–94% compared with year-2019 levels, despite a 2–3-fold growth in demand by 2050. The aviation sector could manage the associated cost increases, with ticket prices rising by no more than 15% compared with a no-intervention baseline leading to demand suppression of less than 14%. These pathways will require discounted investments on the order of US$0.5–2.1 trillion over a 30 yr period. However, our pathways reduce aviation CO 2 -equivalent emissions by only 46–69%; more action is required to mitigate non-CO 2 impacts. Decarbonization of the aviation sector is difficult due to increasing demand and the current lack of scalable mitigation technologies. This Analysis examines pathways towards a net-zero aviation system with improved fuel and aircraft technologies, efficiency gains and contrail avoidance.