Aviation and climate change: The climate mitigation potential of eco-efficient trajectories

By UC3M’s Aircraft Operations Lab

Non-CO2 Emissions: The Overlooked Culprit in Aviation’s Contribution to Climate Change

The aviation industry is responsible for contributing 2% to 5% of global warming. While CO₂ emissions from aircraft have been the primary focus of attention in the last decades, non-CO₂ emissions, such as nitrogen oxide (NOx), aerosols, water vapor, and contrail formation, have an even greater impact on global warming. Recent estimates (interested readers are referred to Lee et al. 2021) suggest that non-CO₂ emissions, particularly nitrogen oxide and cirrus contrails, contribute two-thirds of the global radiative forcing from aviation, making them twice as harmful as CO₂ emissions.

A promising solution by the UC3M’s Aircraft Operations Lab

The UC3M’s Aircraft Operations Lab (https://aircraftoperationslab.com) research team has proposed the idea of designing air trajectories to reduce the environmental impact of aviation on climate change. Unlike CO₂ emissions, non-CO₂ emissions depend heavily on meteorological factors, making it crucial to examine the geographical location of the aircraft, its altitude, and the time of the flight to understand the climate impact of non-CO₂ emissions. By analyzing these factors and understanding the spatial and temporal dependence of emissions, it is possible to mitigate the environmental impact of aviation.

While the development of new propulsion technologies is underway, it will take time to fully integrate these alternatives into the aviation industry. In contrast, a promising short-term solution to reduce the environmental impact of aviation is the design of climate-optimal aircraft trajectories. By modifying aircraft manoeuvres such as departure time, altitude, lateral trajectory, and speed profile, it is possible to avoid emission-sensitive regions and significantly decrease non-CO₂ effects. According to the final results obtained in the project FlyATM4E (https://flyatm4e.eu/), this approach has the potential to reduce the climate impact by 20-50%, with a minimal increase in operating costs of 0.5-3%.

Scientific Gaps

While trajectory optimization techniques show promising results, further research is needed to address scientific gaps in this field. It is important to improve the reliability and quantification of climate impacts associated with aviation emissions, considering factors like meteorological conditions. Incorporating sources of uncertainty into trajectory optimization methods will also provide more robust planning solutions. Studying climate hotspots and incorporating them into network models will enhance our understanding of demand-capacity balance, network complexity, and resilience to shocks.

E-CONTRAIL and RefMap: European Research Projects Paving the Way for Eco-Efficient Trajectories.

Fortunately, this is not the end of the story. European research projects such as E-CONTRAIL, coordinated by Universidad Carlos III de Madrid (Grant Number 101114795), and the RefMap project, in which the university is also involved, are exploring these scientific gaps. This will help to further develop eco-efficient trajectories that aim for a more sustainable future for air transport and contribute to mitigating global climate change.