The aviation CO₂ challenge

The aerospace industry has long been a leading CO₂ emitter. According to ATAG, in 2019 (the last year before COVID-19 disrupted air travel) flights accounted for 2.1% of global emissions, totaling 915 megatons (Mt) of CO₂. This put aerospace industry emissions ahead of numerous industrialized countries including Germany, Iran and Indonesia.

With air travel expected to far surpass pre-COVID-19 levels and approximately double in coming decades, aviation CO₂ emissions will escalate if decarbonization measures are not taken. If 2019 fleets and operations continue, ATAG projects that commercial aviation will generate almost 2,000 Mt CO₂ annually by 2050. A joint study by Shell and Deloitte puts this figure even higher at 2,180 Mt CO₂ — nearly the entire 2019 emissions of India.

The International Air Transport Association (IATA) has taken significant steps to rein in aircraft CO₂ emissions and help decarbonize aviation. Fly Net Zero, an IATA resolution passed in October 2021, aims to bring aviation in line with the objectives of the 2015 Paris Agreement. Fly Net Zero commits the industry to achieving net zero emissions by 2050, with the goal of helping limit global warming to below 2 °C (ideally 1.5 °C) compared to pre-industrial levels.

The aerospace industry has various tools at its disposal to reduce aircraft CO₂ emissions and achieve the ambitious goals of Fly Net Zero. Chief among them are sustainable aviation fuel, efficiency enhancements and carbon offsets.

Sustainable aviation fuel

Sustainable aviation fuel (SAF) is widely considered the industry’s foremost long term decarbonization option. SAF refers to non-fossil-derived fuel approved for commercial aircraft use. Sustainability is typically assessed by third party organizations such as the Roundtable on Sustainable Biomaterials.

Compared with conventional jet fuel, SAF can reduce emissions by up to 80% over the lifecycle of the fuel. Any aircraft certified for the current specification of jet fuel can use SAF with no major changes to aircraft design or supporting infrastructure required.

In 2020, SAF constituted 0.03% of the commercial aviation fuel supply, enabling a reduction of 0.11 Mt CO₂ annually. Extrapolating 2050 data from current trends, SAF will likely range from 6% to 39% of fuel use depending on deployment rates. This will enable an emission reduction of 95-615 Mt CO₂.

Certain “backcast” scenarios suggest that up to 90% SAF fuel use by 2050 is possible if aggressive production, deployment and/or technological advancements are undertaken. These scenarios would enable an emission reduction of well over 1,000 Mt CO₂.

See the Waypoint 2050 report (pp. 72-91) for complete details.

Efficiency enhancements

Efficiency enhancements include design, operations and infrastructure improvements aimed at maximizing fuel economy. Because they can be implemented faster at scale than technological advancements such as SAF, efficiency enhancements will be integral to near term aviation decarbonization efforts. However, long term impacts will taper off as opportunities are exploited and maximum efficiency is approached.

In-service aircraft enhancements include lightweighting, aerodynamic improvements for reduced drag and systems improvements for optimized operations. Infrastructure enhancements include streamlining air traffic management operations and boosting airport energy savings by limiting auxiliary power unit usage, shortening taxi times, employing single engine taxiing and more.

With substantial investments in operations and infrastructure, a net CO₂ reduction of 0.10% per annum (3% overall by 2050) is estimated. In the best case scenario, a reduction of 0.20% per annum (6% or greater by 2050) is possible.

See the Waypoint 2050 report (pp. 60-71) for more details.