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Opinion: How COVID-19 cast a cloud over emission-reduction checks

June 25, 2021

The fall in total aviation CO2 emissions last year implies a huge change to the commitment post-2020.

Richard Evans airline consultant

By Richard Evans, Senior Consultant at Ascend by Cirium.
Originally published in FlightGlobal.

The collapse in passenger traffic due to the COVID-19 pandemic is making life more complicated for anyone wishing to evaluate progress towards carbon-reduction targets.

In 2009 the aviation industry set three global goals: improve average fuel efficiency by 1.5% per annum from 2009 to 2020; net carbon-neutral growth post-2020; and longer term, cutting net carbon dioxide (CO2) emissions to 50% of 2005 levels by 2050.

The most obvious impact is that the fall in total aviation CO2 emissions last year implies a huge change to the commitment post-2020. This has been addressed by the decision to change the baseline for ICAO’s Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) to 2019, rather than the average of 2019 and 2020.

The situation also highlights the lack of clarity around what is meant by an improvement in fuel efficiency, and how progress towards these goals is measured.

The original 2009 commitment did not specify the method of assessment. However, IATA has used emissions per revenue tonne-kilometre (RTK) as the metric, taking into account passengers and cargo.

In its December 2019 Airline Industry Economic Performance report, IATA stated that an annual average improvement of 2.4% had been achieved from 2009 to 2014. The report then quotes a 1.9% efficiency improvement in 2019 versus 2018, but in terms of fuel use per available tonne-kilometre (ATK). At this point, the prediction for 2020, based on the delivery of more fuel-efficient aircraft, was for a further reduction of 2.1%, expressed as per ATK.


The data for 2020 clearly shows the divergence between passenger demand and capacity, and that for cargo. Air freight demand only fell by 9% in 2020, and flights by full-freighter jets grew by over 30%. This highlights that efficiency metrics based purely on passenger figures would clearly give very different results from those derived from aggregate data, including cargo.

Publication of CO2 data by airlines varies enormously, as does their use of efficiency metrics. Airlines that fly relatively little cargo have often used figures for CO2/revenue passenger-kilometre (RPK).

However, on this basis, instead of showing an improvement in 2020, the drastic fall in passenger load factors resulted in an increase in CO2/RPK of around 37%, wiping out the gains of the last 10 years at a global level. This, despite total emissions falling by 48% in 2020 against 2019.

CO2 emissions relative to traffic measures

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Source: Cirium Fleet Forecast, Cirium Tracked Utilization, IATA, Ascend by Cirium analysis

Deciding on the metric, plus verifiable figures for CO2 emissions is key. However, airline traffic data is increasingly difficult to source as many airlines have ceased publishing numbers, other than in annual or quarterly reports. Cirium is developing fuel burn and CO2 models matched with actual flight data, both passenger and cargo, from the start of 2019. This provides a reference point for emissions data, but measuring aggregate industry performance remains a challenge.


Alaska Airlines published its latest environmental, social and governance (ESG) report in March 2021, and commented that its own goal, set in 2013, of cutting CO2/RTK by 20% by 2020 relative to 2009 – adjusted to a reduction of 17% when it merged with Virgin America – would have been met in 2020 if COVID had not intervened. It had achieved a 16% cut by 2016. By this metric, Alaska was 20% worse than 2012 in 2020. It has now restated its goal as being carbon-neutral against 2019 through to 2025, and a goal of net zero emissions by 2040.

EasyJet carries very little cargo, hence its efficiency is measured as CO2/RPK. It restated its target as being a 10% reduction in CO2 emissions per RPK by 2022, versus 2016. For the financial year ended September 2020, it noted that despite the fall in load factors, the focus on flying Airbus A320/A321neo aircraft meant only a marginal increase from 70.4g to 70.8g CO2/RPK was seen. This represents a 4.3% fall since 2016, with the 2022 target being 68g CO2/RPK.

Alaska and EasyJet are two of several airlines that have set goals well beyond the CORSIA target. Offsets will still be part of many airline roadmaps, but the Covid crisis implies the industry does not need these until 2024 at the earliest.

It appears there will be more focus on measurable targets for CO2 reduction, at least in the next four to five years, rather than relying on offsets under the CORSIA scheme.

Further reading: Is this the new way for aviation to track carbon emissions?

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