For many years, the aviation industry has recognized its role in supporting climate goals in alignment with decarbonization initiatives worldwide. In new rules adopted August 30, airlines operating from European airports will be required to report the estimated climate impact of non-CO₂ emissions beginning next year. 

These new rules differ from previous EU environmental measures because they focus on the impact of non-CO₂ emissions.  Generally speaking, the climate impact of aviation is a combination of both direct aircraft engine emissions and non-CO₂ emissions.  These non-CO₂ emissions, such as nitric oxides, sulfur oxides (“soot particles”) and water vapor, are reported by many scientists analyzing climate change as having negative indirect effects on the atmosphere —in particular, a potential warming impact.

What must airlines do?

The new rules will apply starting January 1, 2025, for flights within the European Economic Area (EEA)—that is, the EU plus Iceland, Norway, and Switzerland.  Airlines subject to the regulations will be required to monitor and report non-CO₂ emissions for flights within the EEA. The details of this reporting are contained in the EU legislation, but generally require regulated entities to develop monitoring plans in accordance with detailed provisions of the rules. A valid monitoring plan should describe both the airlines’ monitoring procedure and reporting actions that it will take to ensure compliance. 

Airlines will be required to report once per year, and initially, the requirements will only apply to flights within the EEA.  There is a planned expansion of the new reporting requirements to all flights into and out of the EU by 2027. This phased approach is intended to facilitate the smooth launch of the new reporting requirements.

Debate over the efficacy of new measures 

There has been debate in the aviation industry over the efficacy of the new reporting requirements. After all, the amount—and impact—of non-CO₂ emissions are difficult to measure, due to the effect of variable conditions including engine design, ambient conditions, and fuel composition.  Moreover, the secondary climate effects of non-CO₂ emissions also vary depending on factors such as the location at which they are released, the background atmospheric chemistry, and weather conditions.  However, there is general agreement in the scientific community that, at an aggregate level, non-CO₂ emissions have a net warming impact on the climate. 

For its part, the EU maintains that this very uncertainty—the precise impact of non-CO₂ emissions on climate change—prompted it to pursue the new reporting measures. After all, according to the EU, the airlines’ reporting will provide data for further examination that the EU stated will “enhance” its understanding and contribute to further scientific study of the effect of non-CO₂ emissions.

Nevertheless, airlines have argued that this lack of certainty about non-CO₂ emissions places an undue burden on the airline industry. Notably, they argue, existing measures in the EU’s Emission Trading Scheme (ETS) have already placed requirements on airlines relating to CO₂ emissions.  Industry professionals have also criticized the exemption in the new regulations for certain long-haul flights in and out of the EEA.  These critics have emphasized that selective exemptions weaken the EU’s effort to address the full impact of aviation on the climate.  With more deliberation and data-gathering to come, the period beginning January 1, 2025 will unveil the ease and efficacy of the new reporting measures. Conclusions will then be drawn toward a planned expansion of the requirements in 2027.