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This page gives an overview of the contribution of aviation to climate change and describes how the inclusion of the sector in the EU-ETS works, and how effective it will be.

What is the impact of aviation on climate change?

Emissions from aviation are a significant contributor to climate change. The cumulative impact of aviation on man-made climate change in 2005 was estimated at 4.9%, which comprises the impact of greenhouse gas emissions including carbon dioxide (CO2) and nitrogen oxides (NOx), of the vapour trails and cloud formation triggered by aircraft under certain meteorological conditions, and of soot and black carbon, etc.

Emissions from aviation are growing faster than any other mode of transport. CO2 emissions from EU international aviation increased by 110% between 1990 and 2008. Meanwhile other sectors have reduced emissions. As a result, in Europe they’ve grown from 1.5% of total EU emissions in 1990 to 4.5% today. If unmitigated, aviation emissions are expected to double or triple by 2050 and consume up to one-quarter of the global carbon budget, completely undermining efforts to keep global warming well below 2 let alone 1.5 degrees.

Despite their considerable impact, no measures are in place at regional or global level to address aviation’s non-CO2 climate impacts. The European Commission committed to address cruise NOx emissions when aviation was integrated into the EU ETS in 2008, but has failed to do so. ICAO claims more research into non-CO2 impacts is needed first. Certainly more funding and research is needed to better determine the effects of non-CO2 and how to mitigate them. However, this should not prevent Europe from taking action which is urgently needed. This report, by consultancy CE Delft, examines the latest research on aviation’s non-CO2 climate impacts, and identifies ways to mitigate them. The major impacts come from cruise NOx emissions and contrail and induced cirrus cloud formation. Read our briefing about the non-CO2 effects of aviation here.

Was aviation left out of the Paris agreement?

As emissions from international aviation (and shipping) are not included in national inventories reported under UNFCCC, there was a push to provide specific language to address them in the Paris climate agreement. However, despite a failure to mention them, the objectives of the agreement (Article 4) covers all anthropogenic (ie, man-made) emissions, which therefore includes emissions from international aviation and shipping. It is now up to states to decide whether or not to include them in their NDCs.

The Paris Agreement is silent on who should address these emissions and how. For now, parties are working with the International Civil Aviation Organisation (ICAO). However, unless ICAO significantly increases its ambition, regional and national measures are clearly required. Domestic (national) aviation emission comprise some one-third of global aviation emissions and, of these, US domestic flights account for two-thirds themselves – or about 20% of global aviation emissions. Domestic and intra-EU emission are covered by the EU ETS (which needs strengthening) while China plans to cover its domestic emissions within its own ETS system. Canada has announced a tax on all its domestic aviation emissions, which account for 35% of its domestic emissions.

Does aviation receive subsidies to operate in Europe?

Yes, aviation is heavily subsidised. Firstly, aviation receives a direct subsidy of €3 billion a year for operation and infrastructure developments. Secondly, aviation is exempt from the basic consumer tax, VAT, that is placed on almost every good and service across the EU (apart from a limited number of necessities) leading to a shortfall of at least €7 billion per year in EU member state budgets. Finally, aviation does not pay any fuel tax. On average, across the EU consumers pay 48c per litre of fuel tax every time they fill up their cars, but airlines pay no tax when they fill up their 747s, leading to a shortfall of €32 billion a year across the EU. The aviation agreements negotiated between states (ASAs) contain language which makes it difficult to introduce such taxation. In addition, regional airports and airlines receive billions every year in state aid subsidies.

What is the EU ETS?

The European Union emissions trading system (EU ETS) is a scheme to reduce CO2 emissions by trading and selling emissions permits on a free market where the availability of permits reduces over time. The system operates in 31 countries (all 28 EU countries plus Iceland, Liechtenstein and Norway) and limits emissions from more than 11,000 heavy energy-using installations (such as power stations and metal factories) and, since 2012, airlines. It covers around 45% of the EU's greenhouse gas emissions. To read more, see Aviation in the ETS.

What is ICAO’s global market-based measure?

In October 2016 ICAO agreed the outlines of a global market-based measure to address CO2 emissions from international aviation, starting as a voluntary measure from 2021. The Carbon Offsetting and Reduction Scheme for International Aviation, or CORSIA, aims to stabilise CO2 emissions at 2020 levels by requiring airlines to offset the growth of their emissions after 2020. The measure will be voluntary until 2027 and mandatory thereafter. Some 71 states have so far opted into the voluntary phase meaning about 80% of the promised “carbon-neutral growth in 2020” will be addressed. However, the 2016 ICAO assembly did not finalise many of the details which will be critical in determining the CORSIA’s environmental effect. For example, environmental and double-counting criteria for offsets; whether and how an emissions register could function; monitoring, reporting and verification; how to account for aviation biofuel usage; compliance and enforcement. Protracted and difficult negotiations on these issues continue.

Even if offsetting can be made to work, it can only ever be a temporary solution as the Paris agreement requires all sectors and all states to reduce their emissions, not just pay others to reduce theirs. The low cost of offsets and weak ambition of the CORSIA will provide no incentive for the aviation sector to drive efficiency improvements.

How well does offsetting work?

In an offsetting scheme like CORSIA, a polluter pays others to reduce emissions in order to pollute more itself. According to a recent study commissioned by the European Commission, 85% of the offset projects under the UN’s Clean Development Mechanism (CDM) used by EU member states failed in the objective of reducing emissions. Many offsets examined failed to deliver "real, measurable and additional" emission reductions. The projects investigated made false assumptions of alternative scenarios or were likely to have happened anyway. This report calls into question the decision to rely almost exclusively on offsetting to meet aviation’s inadequate climate target after 2020.

The EU has decided to no longer allow member states after 2021 to use offsets when meeting their 2030 climate targets, marking a major step forward in European climate policy. Yet at the same time Europe is now endorsing just such an approach at ICAO to address international aviation emissions.

Will biofuels and technology bring aviation emissions down?

As present, there are no credible forecasts suggesting that sustainable biofuels can make any noticeable dent in aviation’s fossil fuel demands for the foreseeable future. Arable land is a limited resource. Land-based biofuels are therefore not truly ‘renewable’ since the land used is lost for other purposes, including food production, carbon sequestration, nature, and to ensure the livelihoods of communities. Sustainable feedstocks available for production of non-land-based biofuels, made of waste and residues, are limited and there are other sectors competing for access to them.

In a similar fashion futuristic aviation technologies, whether electric or hydrogen-powered aircraft, are many decades away. In addition, technological improvements of future aircraft in the 2030-2040 time frame have already largely been factored into the ICAO CO2 standard work and reveal no silver bullets – rather an ever diminishing annual improvement in new aircraft efficiency of about 1% or less is evident.