Abstract
The compact Earth system model OSCARv2.2 is used to assess the climate impact of present and future civil aviation carbon dioxide (CO2) emissions. The impact of aviation CO2 on future climate is quantified over the 1940–2050 period, extending some simulations to 2100 and using different aviation CO2 emission scenarios and two background Representative Concentrations Pathways (RCP2.6 and RCP6.0) for other emission sectors. Several aviation scenarios including weak to strong mitigation options are considered with emissions ranging from 386 MtCO2/year (Factor 2 scenario) to 2338 MtCO2/year (ICAO based scenario) in 2050. As a reference, in 2000, the calculated impact of aviation CO2 emissions is 9.1 ± 2 mK (0.8% of the total anthropogenic warming associated to fossil fuel emissions). In 2050, on a climate trajectory in line with the Paris Agreement limiting the global warming below 2 °C (RCP2.6), the impact of the aviation CO2 emissions ranges from 26 ± 2 mK (1.4% of the total anthropogenic warming associated to fossil fuel emissions) for an ambitious mitigation strategy scenario (Factor 2) to 39 ± 4 mK (2.0% of the total anthropogenic warming associated to fossil fuel emissions) for the least ambitious mitigation scenario of the study (ICAO based). On the longer term, if no significant emission mitigation is implemented for the aviation sector, the associated warming could further increase and reach a value of 99.5 mK ± 20 mK in 2100 (ICAO based), which corresponds to 5.2% of the total anthropogenic warming under RCP2.6. The contribution of CO2 is estimated to represent 36%–51% of the total aviation radiative forcing of climate including short-term climate forcers. However, due to its long residence time in the atmosphere, aviation CO2 will have a major contribution on decadal time scales. These additional short-terms forcers are subject to large uncertainties and will be analysed in forthcoming studies.
Highlights
The OSCARv2.2 compact climate change model In this study we use the OSCAR compact Earth System Climate Change Model to investigate the impact of CO2 emissions from the aviation sector on climate
The impact of aviation CO2 emissions on future climate has been quantified over the 1940–2050 period, extending some simulations to 2100 and using different aviation CO2 emission scenarios and two background Representative Concentrations Pathways (RCP2.6 and RCP6.0) for other emission sectors
Several aviation scenarios including weak to strong mitigation options have been considered, ranging from 386 MtCO2/yr (Factor 2 scenario) to 2338 MtCO2/yr (ICAO based scenario) in 2050
Summary
In 2017, worldwide flights carried nearly 4.1 billion passengers and produced 859 million tonnes of CO2 (ATAG 2019). The growing aviation sector is expected to experience a three-fold increase between 2000 and 2050 in terms of passengers (Berghof et al 2005, Horton 2006). Airbus plans a 4.6%/yr increase in the average annual global air traffic rate over the 20 years (2015–2034) (Airbus 2016), while Boeing forecasts a 4.9%/yr increase over the same period (Boeing 2015). Between 1995 and 2010, the aviation sector recorded an average yearly growth rate of 4.6%/yr in terms of revenue-passenger-kilometres, despite the drop linked to the world economic recession in 2008. The mean annual growth rate is projected to remain constant (4.1%/yr) over the 2015–2025 period (ICAO 2019a), which could make the aviation sector a significant fossil fuel CO2 emitting sector in the future (2050)
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