The reductions required under the Kyoto Protocol include domestic aviation but exclude international emissions from this sector (as well as emissions from international shipping). The UNFCCC has given responsibility for international aviation to the International Civil Aviation Organisation (ICAO).

Going forward, it is essential that both domestic and international aviation are covered by  a mechanism, or mechanisms, to reduce global emissions:

• Global CO₂ emissions from aviation (domestic and international) are currently 0.5-0.7GtCO₂, which is equivalent to about 1.9 - 2.4% of total global CO₂ emissions. Global international aviation accounts for roughly half of total aviation emissions.
• Global demand for aviation has increased at roughly 5% per annum over the past decade.  
• In the absence of policy action, future projections of aviation emissions suggest that global aviation emissions could reach 2.4 GtCO₂ in 2050. This would be around a four-fold increase on today’s levels.

How does aviation contribute to global CO2 emissions?

Global aviation (both domestic and international together) currently represents around 2% of global CO₂ emissions, but, if left unchecked, could account for 15-20% of all CO₂ permitted in 2050. This would mean other sectors having to make much deeper cuts in their emissions in order to meet a global emissions reduction target of 50% by 2050.

What can be done to reduce global aviation emissions?

In a letter last year to the Secretaries of State for Transport and Energy and Climate Change, the Committee set-out their advice to the previous Government on what options should be considered for reducing global aviation emissions. The former Government asked for this advice ahead of the climate change summit in Copenhagen in December 2009..

The Committee advised that:

• Aviation CO₂ emissions should be capped, either through a global sectoral deal or through including (domestic and international) aviation emissions in national / regional (e.g. EU) emissions reduction targets.
• Ideally all aviation CO₂ emissions would be capped. It may be necessary; however, that there is an interim phase where the cap applies to all departing and arriving flights in developed countries with exemptions for intra-developing country flights.
• The level of emissions reduction ambition under any international agreement should be no less than that already agreed by the EU (i.e. developed country net emissions in 2020 should be no more than 95% of average annual emissions from 2004-06).
• Emissions allowances should be fully auctioned to prevent airlines benefiting from windfall profits that would ensue under a free allowance allocation system.
• Auction revenues are one of a number of potential sources of funding for adaptation that should be agreed at Copenhagen.
• Radical innovation in engine, airframe and fuel technology is required to reduce aviation emissions in the period to 2050; and a funding source for aviation R&D should be identified as part of a deal.
• Emissions trading and offsetting offer useful short to medium term flexibility for meeting aviation targets, but in the long-term, the aviation industry should plan for deep cuts in its own CO₂ emissions, with developed countries keeping aviation emissions at 2005 levels in 2050.
• Additional non-CO₂ effects (e.g. NOx, cirrus, contrails) from aviation are contributing to global warming. The effects of these should be addressed within a global deal on aviation.

The CCC has conducted a review into UK Aviation emissions to analyse how emissions from UK aviation can return to 2005 levels or lower by 2050. This also includes analysis of how technology can be used to reduce emissions from planes. The insights from this report are relevant to the global context.

(Read the letter).

What is the UK’s share of international aviation emissions?

There are several ways in which international aviation emissions can be allocated. These include bunker fuels and nationality of the airline. These and other methodologies suggest that the UK is responsible for around 8% of global emissions from international aviation. The same methodologies give considerable variation for other countries’ shares of emissions, and there is no international agreement on an appropriate allocation methodology.

Why are international aviation emissions not included in the carbon budgets?

The budgets, in line with the Committee’s advice, exclude emissions from international aviation and shipping for the time being given complexity arising from differences in appropriate emissions allocation methodologies [insert link to advice on this from 1st report]. Aviation is, however, included within the EU’s 20% and 30% GHG emission reduction targets. Our budget proposals were based on that framework and do, therefore, implicitly take account of international aviation emissions.