Supporting research for monitoring non-CO2 effects in aviation
August 26, 2026
Supporting research for monitoring non-CO2 effects in aviation
DLR researchers outline potential pathways for integrating aviation non-CO2 effects into the EU ETS
Non-CO2 effects account for a substantial share of aviation’s climate impact. A DLR study published in the Nature Portfolio journal Communications Earth & Environment brings together the scientific foundations for monitoring these effects within the European non-CO2 monitoring system and examines the challenges involved in its further technical and regulatory development under the European Emissions Trading System.
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Non-CO2 effects account for around two-thirds of aviation’s climate impact.
A DLR study in Communications Earth & Environment summarises the scientific foundations of the European monitoring system for non-CO2 effects.
Further research and development is needed to determine the technical and regulatory framework for including these effects in the EU Emissions Trading System.
Aviation affects the climate not only through carbon dioxide (CO2), but also through so-called non-CO2 effects. These include nitrogen oxides (NOₓ), water vapour, soot particles and the formation of contrails. These effects alter chemical and microphysical processes in the atmosphere and influence the Earth’s radiation balance – often in complex ways that depend on location, time and weather conditions. Around two-thirds of aviation’s climate impact is attributable to non-CO2 effects.
As part of the reform of the European Emissions Trading System (EU ETS), it was decided at the end of 2022 that airlines would also be required to monitor these non-CO2 effects from 1 January 2025. To support implementation, EUROCONTROL provides NEATS (Non-CO2 Emissions Accounting and Tracking System), software that automatically calculates the non-CO2 climate impact of individual flights.
Assessing the climate effects of aviation more comprehensively and mitigating them more effectively in future
The study1, published in Communications Earth & Environment (Nature Portfolio), brings together scientific findings and methodological approaches developed by DLR that have contributed to the development of the European MRV system (Monitoring, Reporting and Verification). It describes how the climate effects of aviation can be scientifically assessed and what methodological requirements need to be met to avoid misleading incentives and support effective climate action.
At the same time, the study highlights the need for further research and development regarding the technical and regulatory design of the system. This is particularly due to remaining scientific uncertainties in the assessment and evaluation of non-CO2 effects, as well as the potential inclusion of additional effects, in particular the impact of aerosols on clouds and economic impacts.
The study was led by the DLR Institute of Atmospheric Physics, with contributions from the DLR Institute of Air Transport and the DLR Institute of Propulsion Technology.
1Grewe, V., Niklaß, M., Dahlmann, K., Eichinger, R., Matthes, S., Lau, A., Scheelhaase, J., Linke, F., Plohr, M. “Pathways for including non-carbon dioxide aviation climate effects in the European Emission Trading System”, Commun Earth Environ 7, 243 (2026). https://doi.org/10.1038/s43247-026-03265-w
