What's happening? Under the United Nations Framework Convention on Climate Change (UNFCCC), emissions from international aviation are treated separately in national accounting. The 1997 Kyoto Protocol requested developed countries to work through the International Civil Aviation Organisation (ICAO) to limit and reduce emissions from the sector. After years of waiting for ICAO to take action in dealing with the aviation sector’s climate impact, the EU agreed in 2008 that emissions from international aviation would be included in its emissions trading system (EU ETS) from 1 January 2012. Read more about aviation’s trajectory in the EU ETS here. In October 2016 ICAO agreed on a global market-based measure to address the growth in CO2 emissions from international aviation above 2020 levels. 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. However, it will be voluntary from 2021-2027, potentially only have mandatory effect after 2027, and will, at a maximum, offset only 21.6% of international aviation emissions. The problems with offsetting have been made clear by a recent European Commission study. This study has found that 85% of the offset projects under the UN’s Clean Development Mechanism (CDM) failed in the objective of reducing emissions. The aviation sector now runs the risk of repeating these mistakes by resorting to offsetting its emissions – particularly as rules governing the offsets’ environmental integrity in CORSIA are unknown. 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 CORSIA will provide no incentive for the aviation sector to drive efficiency improvements. And in any case, the measure will not reduce fuel burn or the alarming growth rate of emissions. It is therefore essential that other global measures are agreed, especially measures that advance in-sector reductions, such as an efficiency standard for aircraft and ending subsidies. While ICAO continues to set only minimal climate ambition, it is important that the EU joins other developed regions and countries in showing leadership on this issue. The EU should therefore ensure that reductions in aviation sector emissions make a fair contribution to achieving the EU’s overall 2030 climate target, and it should adopt measures that ensure the sector makes its fair contribution to reducing Europe’s emissions. This includes ending tax exemptions and subsidies and investing in low-carbon alternatives.