The climate impact of aviation resulting from both $$\text {CO}_2$$ emissions and $$\text {non-CO}_2$$ effects is gaining attention from aviation stakeholders seeking to identify potential mitigation options. There is a need to consolidate the use of assessment methods and climate metrics, which are required to convert aviation $$\text {non-CO}_2$$ effects into $$\text {CO}_2$$ -equivalent emissions. We provide an overview of the operational, technological and scenario-based climate impact assessment methods that have been applied in literature as well as considerations and requirements for the choice of climate metric. We propose a four-layer technology climate impact assessment methodology, which includes: (1) the technology parameters, such as entry into service and temporal and spatial network use; (2) the calculation of three-dimensional aircraft trajectories and emission inventories; (3) the calculation of radiative forcing and induced temperature change time series; and (4) the overall climate impact, measured using a climate metric. We recommend two climate metrics that best fulfill the requirements, the Average Temperature Response (ATR100) and the Efficacy-weighted Global Warming Potential (EGWP100), both over 100 years. Additionally, we discuss further steps, such as the understanding of the most sensitive parameters in this approach, how uncertainties can be included to provide robust estimates, aspects of verification and update possibilities for new findings in research.

In the frame of the final analysis of the HERFUSE activities a life cycle assessment (LCA) has been planned to support the performance evaluation of the new Clean Aviation (CA) architectural concepts. The HERFUSE project is focused on designing innovative fuselage and empennages suitable for the future Hybrid-Electric Regional Aircraft (HER) that will contribute to the overall target to reduce greenhouse gas (GHG) emissions. HERFUSE will study the challenges in fuselage and empennage layout, material, components, manufacturing and assembly derived from the integration of the relevant fuselage systems for HER as defined in the strategic research and innovation agenda SRIA for a Hybrid-Electric Regional Aircraft and in HER-01 topic.

This work provides an extensive analysis of the different methodologies and related findings and implications of several projects that address the climate impact of aviation. By analyzing EU-funded initiatives and other significant projects worldwide, several critical insights have been drawn about how aviation contributes to climate change and the potential pathways to mitigate these impacts.