Understanding Carbon Offsets

Don’t airlines already offset their GHG emissions?

Prospective carbon credit buyers may have heard that the aviation industry is already taking steps to reduce their GHG emissions. While this is true, the reality is that regulatory coverage of aviation emissions is highly uneven, and even where it exists it does not fully address their climate impacts.

Aviation GHG emissions have been a subject of international climate negotiations for decades, but reducing them has proven challenging. The Kyoto Protocol called for richer countries to limit emissions from international aviation, working through the International Civil Aviation Organization (ICAO). In 2008, seeing little progress under ICAO, the European Union (EU)  adopted legislation to include emissions from both domestic flights (within the EU) and international flights (to or from the EU) in its Emissions Trading System (the EU ETS). However, the international aviation industry objected to the inclusion of international flights, and in 2012 the EU granted an exemption for them, allowing ICAO time to develop its own emissions reduction plan.

ICAO subsequently established a goal of “carbon-neutral growth” in international aviation emissions after 2020. Under this framework, emissions may continue to rise overall, but participating airlines agree to reduce what they can (through improved efficiency and use of alternative jet fuels) and offset any remaining emissions. In 2016, ICAO adopted the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) to help achieve this offsetting goal.

While the EU and ICAO regulatory efforts are laudable as far as they go, individual flyers concerned about their carbon footprints should keep in mind several qualifications:

  • Not all airlines will initially participate in CORSIA. As of April 2020, 83 countries – representing just over ¾ of international aviation activity – plan to participate in CORSIA’s pilot phase (2021-2023) and first formal phase (2024-2026). Notable exceptions include China, India, and Brazil. For international flights on airlines based in non-participating countries, emissions will not be offset by CORSIA.
  • CORSIA will only address a portion of emissions. As noted, the goal of CORSIA is to offset any growth in emissions from international aviation after 2020. The baseline for measuring this growth will be set at the average annual emissions over 2019-2020 (this is now under debate, because of the effect of the COVID-19 pandemic on aviation in 2020). This decision means that net emissions from international aviation will likely continue to be around 600-700 million metric tonnes of CO2 per year, leaving plenty of emissions for individual travelers to voluntarily offset (CORSIA is set to run through 2035).
  • Outside the EU, there is little – if any – regulation of GHG emissions from domestic flights. There are no parallel restrictions in other major countries for emissions from domestic flights, which leaves a large percentage of aviation emissions uncovered – about 2/3rds of global GHG emissions from commercial aviation are from domestic flights (ICCT, 2018).
  • Regulation by the EU ETS will not eliminate emissions from domestic flights. Under the EU ETS, all airlines operating in Europe are required to monitor, report, and verify their emissions, and to surrender an equal amount of allowances (emission permits). The EU ETS aims to make CO2 intensive activities, such as flying, less cost-effective. But the price pressure has been limited so far, and domestic flights still result in net emissions.
  • None of these regulatory systems account for the knock-on effects of combusting jet fuel at high altitudes. As noted in the preceding pages, aviation emissions have a greater impact on climate than the simple radiative forcing effect of CO2. Yet regulatory approaches so far have addressed aviation emissions as if they were equivalent to emitting CO2 at ground level. Thus, even with complete regulatory coverage, it would still be advisable to avoid air travel and – where avoiding it is not possible – offset its (remaining) climate impact.