The Climate Impact of Aviation

Main conclusions from the report:

Technology development is crucial for reducing the climate impact of aviation

The historical and continuous growth in international aviation activity is significant, and greenhouse gas emissions from aviation are not on track to reach net-zero. In addition, aviation affects the climate through the aircraft contrails often seen in the sky and through other so-called non-CO2 effects. There are several ways to reduce the climate impact of aviation and the analysis of the Danish Council on Climate Change shows that early development and deployment of technologies is crucial.

Some technologies offer solutions that reduce aircraft emissions and other offset emissions from aviation through permanent negative emissions. Offsetting means that aviation industry actors continue to use fossil fuels but compensate for their emissions by purchasing carbon credits representing carbon capture and storage in another sector corresponding to emissions from fossil aviation fuels.

Most technologies with significant reduction potential are difficult to scale up quickly

Most of the technologies that could, in theory, enable aviation to reach net zero emissions are currently only on the verge of technological maturity, while also being costly and highly resource intensive. For biofuels, the use of bioresources is a particular drawback, while for synthetic fuels, the main challenge is the consumption of non-fossil electricity in a power system not yet fully transitioned.

The Danish Council on Climate Change examines two different ways of compensating for aviation emissions via deployment of permanent carbon removal technologies. One option is BECCS, which captures CO2 from flue gas at bio-energy plants or other plants and stores it permanently underground. This solution involves significant consumption of scarce bioresources. Another option is DACCS, which captures CO2 directly from the air and stores it permanently underground. Both technologies require underground CO2 storage capacity. This capacity may be limited and is also expected to accommodate CO2 from other sectors as well as CO2 removed from the atmosphere. In addition, using BECCS and DACCS to offset emissions from aviation maintains the sector’s dependency on fossil energy sources and associated infrastructure.

Horizontal measures such as energy efficiency and contrail avoidance rerouting are useful solutions, but they are not sufficient on their own. Overall, significant challenges remain in relying on technologies to fully address climate impact of aviation.

Flying less will ease the challenge

Although there is no doubt that technology will be crucial to reducing aviation climate impact, the challenges described above also make it clear that reducing this impact will become significantly easier, if people fly less. EU legislation plays an important role both in promoting genuine low-carbon technologies and in incentivising people to fly less by affecting airline ticket prices.

EU compliance rules should ensure low climate impact from technologies

The EU regulates emissions from European aviation through the Emissions Trading System and through increasing blending requirements for biofuels and synthetic fuels in aviation jet fuel. Regarding the fuel blending mandate, it is crucial that the corresponding greenhouse gas inventory rules for compliance are robust if the mandate is to ensure a genuine reduction in climate impact. The Danish Council on Climate Change finds that not all emissions from biofuels and synthetic fuels are fully accounted for, and that the EU compliance rules can be strengthened further to reduce the carbon footprint.

EU policy should promote technology and the polluter pays principle

By expanding the scope of the Emissions Trading System to cover emissions from all flights departing from the EU, rather than only intra-European flights, the EU can extend the advantages of the current system. The carbon allowance price reduces greenhouse gas emissions cost-effectively, particularly through energy efficiency as it will reduce air travel due to the impact on airline ticket prices. However, the ETS is not sufficient in its own as the carbon allowance price is too low to drive technology development in the aviation sector. Thus, sector-specific regulation such as the fuel blending mandate for aviation is relevant.

However, as the analysis of the Danish Council on Climate Change shows there are currently considerable challenges related to upscaling biofuels and synthetic fuels. Consequently, it is relevant to increase technology neutrality in the regulation. This can be achieved by allowing DACCS as a compliance option under the fuel blending mandate, as an alternative to biofuels and synthetic fuels, provided that the overall level of ambition is maintained. Moreover, the Council finds that EU should regulate global warming impacts from non-CO2 effects and the sector’s consumption of land-use intensive bioresources.

Due to the high costs of available technologies in the aviation sector it should be considered whether the level of activity is proportionate to its climate impact. Today, neither airlines nor passengers are faced with the true costs for society of flying. By ensuring that polluters pay a higher share of the costs of emissions, the EU can effectively reduce aviation activity.

Recommendations

Ensure robust carbon footprint compliance rules for technologies

• The EU should strengthen its existing accounting rules for biofuels and synthetic fuels. The EU should make all biofuels and synthetic fuels subject to carbon footprint requirements and tighten the rules to ensure accurate inventory of emissions and to further reduce the climate impact of biofuels and synthetic fuels.
• The EU should ensure accurate accounting of the climate benefit of carbon credits. If aviation industry actors are to be allowed to fulfil their fuel blending obligations through the purchase of carbon credits from permanent negative removals of CO2, those credits should only be allocated the share of the climate benefit that is in fact financed by the carbon credit. If the climate benefit of a project is co-financed through state aid or sales to the Emissions Trading System, carbon credit purchases should only be allocated a proportionate share of that climate benefit. 

Strengthen the regulation of climate impacts

• The Emissions Trading System should be expanded to include all departing flights. The expansion should be designed to ensure appropriate interaction with other sectors covered by the Emissions Trading System, as well as with aviation-related regulation at both the EU and UN levels. An expansion would also help ensure that the EU’s share of international aviation emissions is on track towards net-zero.
• The EU should regulate non-CO2 effects. The EU should regulate aviation non-CO2 gases and particles that affect the climate. In the short term, the EU could e.g. reward airlines actively avoiding contrails by rerouting or airlines using low-aromatic fossil jet fuel. In the 2026 revision, non-CO2 effects should also be integrated into the Emissions Trading System, at least based on conservative assumptions about the climate impact. Once the evidence base is sufficiently robust, non-CO2 effects should be fully integrated into an expanded Emissions Trading System equivalent to the CO2 emissions.
• The EU should reduce the consumption of bioresources. The EU should introduce measures to limit the consumption of bioresources in the long term. Within the current regulatory framework, the EU has several options, including strengthening existing accounting rules for the use of biogenic CO2 in the production of synthetic fuels.

Increase flexibility in the sector-specific regulation

• Sector-specific regulation of aviation should be maintained. The EU should maintain regulation of aviation emissions through the Emissions Trading System, complemented by a sector-specific regulation. The current fuel blending mandate and its level of ambition should be maintained and enforced to provide a stable and clear incentive across the aviation sector and the entire value chain of the fuel industry.
• Offsetting emissions through DACCS should be allowed as a flexible compliance option under the blending mandate. The EU should allow compensation of emissions through DACCS specifically as a flexible compliance option under the overall blending obligation in ReFuelEU Aviation. However, the DACCS option should be subject to periodic reviews and ongoing evaluation and be conditional to full compensation of the aggregated climate impacts across sectors. This is due to e.g. the drawback of continued fossil fuel consumption and the uncertainty associated with CO2 storage capacity.

Make costs explicit and prioritise support for development over operating subsidies 

• The full costs should be reflected in ticket prices. Currently, the EU subsidises the price gap between alternative fuels and fossil fuels, thereby lowering the costs of flying. These subsidies should be reduced or fully abolished so that passengers face the true costs of flying through the ticket prices.

• Financial support should prioritise development support over operating subsidies. The EU should aim to reduce investment risks in biofuel and synthetic fuel industries and other relevant technology areas, including DACCS, electric aircrafts and non-CO2 mitigation technologies, through support for development and early-stage scale-up.

   

Download the English summary or access the full report (in Danish) here.