International Aviation

Critically Insufficient4°C+ World

NDCs with this rating fall well outside of a country’s “fair share” range and are not at all consistent with holding warming to below 2°C let alone with the Paris Agreement’s stronger 1.5°C limit. If all government NDCs were in this range, warming would exceed 4°C. For sectors, the rating indicates that the target is consistent with warming of greater than 4°C if all other sectors were to follow the same approach.

Highly insufficient< 4°C World

NDCs with this rating fall outside of a country’s “fair share” range and are not at all consistent with holding warming to below 2°C let alone with the Paris Agreement’s stronger 1.5°C limit. If all government NDCs were in this range, warming would reach between 3°C and 4°C. For sectors, the rating indicates that the target is consistent with warming between 3°C and 4°C if all other sectors were to follow the same approach.

Insufficient< 3°C World

NDCs with this rating are in the least stringent part of a country’s “fair share” range and not consistent with holding warming below 2°C let alone with the Paris Agreement’s stronger 1.5°C limit. If all government NDCs were in this range, warming would reach over 2°C and up to 3°C. For sectors, the rating indicates that the target is consistent with warming over 2°C and up to 3°C if all other sectors were to follow the same approach.

2°C Compatible< 2°C World

NDCs with this rating are consistent with the 2009 Copenhagen 2°C goal and therefore fall within a country’s “fair share” range, but are not fully consistent with the Paris Agreement long term temperature goal. If all government NDCs were in this range, warming could be held below, but not well below, 2°C and still be too high to be consistent with the Paris Agreement 1.5°C limit. For sectors, the rating indicates that the target is consistent with holding warming below, but not well below, 2°C if all other sectors were to follow the same approach.

1.5°C Paris Agreement Compatible< 1.5°C World

This rating indicates that a government’s NDCs in the most stringent part of its “fair share” range: it is consistent with the Paris Agreement’s 1.5°C limit. For sectors, the rating indicates that the target is consistent with the Paris Agreement’s 1.5°C limit.

Role model<< 1.5°C World

This rating indicates that a government’s NDC is more ambitious than what is considered a “fair” contribution: it is more than consistent with the Paris Agreement’s 1.5°C limit. No “role model” rating has been developed for the sectors.

1.5°C Compatible< 1.5°C World

Definition of the sector

International aviation – which refers to flights that take off in one country and land in another - is generally not covered by countries’ NDCs. International aviation currently contributes 1.2% of global GHG emissions - or about 600 MtCO₂ annually (IEA, 2019). Total aviation emissions – that is emissions from both international and domestic flights - contributed approximately 2.4% of total global CO₂ emissions in 2018 (Graver, Zhang and Rutherford, 2019).

Our assessment is of international aviation only. GHG emissions from domestic aviation are considered as part of national totals and are included in the assessment of individual CAT countries.

Gas Coverage

Due to data availability, our analysis is limited to CO₂ emissions. However, international aviation is also a source of non-CO₂ emissions and impacts that contribute to global warming, including NO_x and water vapour (H₂O), which, when emitted at altitude, forms contrail cirrus (Owen, Lee and Lim, 2010). Contrail cirrus traps heat that is radiated from the Earth’s surface back to the atmosphere.

Historical emissions

Historical CO₂ emissions from 1990 to 2017 were taken from the IEA.

Sector Target

The sector’s target is to achieve carbon neutral growth relative to 2020 levels. In other words, international aviation’s net CO₂ emissions should remain constant at those levels.

The precise level for carbon neutral growth is set at the average of emissions in 2019-2020 (ICAO Assembly, 2016b, paragraph 11). When the ICAO Assembly set this target in 2013, the organisation and airlines anticipated 2020 CO₂ emissions to be approximately 682-775 Mt (ICAO, 2013b). However, due to COVID-19 international aviation emissions will be much lower than this level.

IATA has requested that the ICAO Council take 2019 emissions as the baseline to avoid that airlines face higher obligation requirements than previously expected. At the time of writing, however, it is uncertain what decision ICAO will take with regards to the baseline for the target of carbon neutral growth. This CAT assessment rates the target based on the 2019 baseline, but also provides a baseline composed of average emissions in 2019 and 2020 baseline as a reference point. To determine this latter baseline, we assumed 2020 emissions are 60% lower than those in 2019.

To calculate 2019 emissions, we extrapolated emissions from 2017, the last year for which data is available, using an average of the 2014-2017 growth rate. Considering economic conditions, we expect emissions in 2018 and 2019 to resemble the same growth rates as in previous years, when growth rates fluctuated between 3-6% and have therefore used an average rather than the growth rate of 2017 – which was at the high end of the range.

As of 1 January 2019, all ICAO Member States that had aircraft operators undertaking international flights are required to implement a CORSIA Monitoring Reporting and Verification (MRV) system (ICAO, 2018). This system allows ICAO to collect data on CO₂ emissions from international aviation on an annual basis; establish the baseline for carbon neutral growth; and compare emissions in future years to the baseline. ICAO’s data on international aviation emissions in 2019 is not publicly available and may differ from our estimate. We will update our assessment as more data becomes available.

Current policy projections

We based the pre-COVID current policy projections on the projections in ICAO’s Environmental Report of 2019 (ICAO, 2019b). As ICAO does not provide exact data points for future years, we extracted data points from the ‘optimistic technology improvements’ and the ‘low technology improvements’ trajectories for 2015 to 2050 with five-year intervals from the graphs in the report. The historical emissions used by ICAO are very close to historical emissions as provided by the IEA, so we did not need to harmonise the data.

We also developed two scenarios to evaluate the impacts of COVID-19 on international aviation emissions. The assumptions related to the impacts of COVID-19 are explained in the current policies section. To assess the impact on emissions until 2030, we applied the growth rates using the ICAO’s optimistic and low technology scenarios.

We used these two scenarios, so we could develop an upper and lower bound for emission projections based on current policies. The Environmental Report does not explain what assumptions these scenarios consider.