Simulation and evaluation of sustainable climate trajectories for aviation

TL;DR

This paper introduces CAST, a simulation tool for evaluating climate impact scenarios of aviation, analyzing how different strategies and growth rates affect the sector's contribution to global warming limits.

Contribution

Development of CAST, a novel simulation tool that models aviation's climate impact using a carbon budget approach and evaluates various mitigation scenarios.

Findings

Aviation could consume 2.9%-3.5% of the carbon budget for 2°C warming.

Air traffic growth rates between -1.8% and +2.6% are compatible with +2°C targets.

Mitigating contrails is crucial for reducing non-CO2 climate effects.

Abstract

In 2019, aviation was responsible for 2.6% of the world CO2 emissions as well as additional climate impacts such as contrails. Like all industrial sectors, the aviation sector must implement measures to reduce its climate impact. This paper focuses on the simulation and the evaluation of climatic scenarios for the aviation industry. For this purpose, a specific tool (CAST for "Climate and Aviation - Sustainable Trajectories") has been developed. This tool follows a methodology adapted to aviation using the concept of carbon budget and models of the main levers of action such as the level of air traffic, reduction of aircraft energy consumption or energy decarbonisation. These models are based on trend projections from historical data or assumptions from the literature. Several scenario analyses are performed in this paper using CAST and allow several conclusions to be drawn. For instance, the modelling of the scenarios based on the ATAG (Air Transport Action Group) commitments shows that aviation would consume between 2.9% and 3.5% of the world carbon budget to limit global warming to 2{\deg}C and between 6.5% and 8.1% for 1.5{\deg}C. Also, some illustrative scenarios are proposed. By allocating 2.6% of the carbon budget to aviation, it is shown that air transport is compatible with a +2{\deg}C trajectory when the annual growth rate of air traffic varies between -1.8% and +2.6%, depending on the considered technological improvements. However, in the case of a +1.5{\deg}C trajectory, the growth rate would have to be reduced drastically. Finally, analyses including non-CO2 effects compel to emphasize the implementation of specific strategies for mitigating contrails.