Aviation and Climate Change: A Brief Overview of the Issues

By Stephane Amant, Senior Manager in charge of the Mobility Division

CO2 Emissions from Commercial Aviation Today... and Tomorrow!

Today: approximately 800 MtCO2 excluding the fuel supply chain and approximately 1,000 MtCO2 including it. That is, approximately 2.5% and 3% of total global CO2 emissions, respectively (source: International Energy Agency, IEA). If we take into account other non-CO2 effects (contrails and induced high-altitude cirrus clouds), these figures must be increased (by 20% to much more, depending on the scientific studies; the uncertainty mainly stems from issues of measurement). That is as much as Germany’s emissions, and more than the combined emissions of France and the United Kingdom (source: SDES). If aviation were a country, It would be the sixth-largest emitter of the planet. That is 6 to 7 times less than road transport (passengers and freight), but as much as the chemical industry (source: IEA). Looking ahead: if we apply the ICAO’s central aviation development scenario (with an average annual energy efficiency gain of 1%) to the IEA’s 2°C scenario (for other sectors), aviation’s share of total CO₂ emissions will rise to 7% in 2035 … and 15% by 2050 (Carbone 4 calculations). That amounts to approximately 2,400 MtCO2—more than the entire steel industry emits today. It would become the second-largest emitting sector in the economy, after road transportation.

Why are carbon offsets only a short-term solution?

For at least two reasons, the aviation sector cannot rely on carbon offsets in the long term to comply with the Paris Agreement. The first reason (the most misunderstood, but the most decisive) is evident in the analyses conducted by the IEA based on the IPCC’s findings. These analyses clearly confirm that aviation must halve its emissions between 2005 and 2050 …but in absolute terms, without taking offsets into account. Why? Because the overall mitigation target is such that it requires very significant direct reductions across all sectors, on the one hand, and strengthened measures to carbon storage land-use type in addition On the other hand … what excludes the possibility of offsets. In other words, A reduction cannot be transferred from one sector to another (definition of the offset) because both are needed to achieve the goal. Furthermore, even assuming that a limited number of offsets remain available, strong competition from other sectors with equally ambitious reduction targets (such as the maritime sector) will mean that their availability for aviation alone will be low relative to its needs. Therefore, there remain energy efficiency and the Sustainable Aviation Fuels (SAF)!

The dilemma of traffic growth: Is it compatible with the Paris Agreement?

It is widely acknowledged that energy efficiency gains in operations, combined with improved airspace management, are largely insufficient to offset the sharp rise in traffic (which doubles every 15 years). As a result, emissions are rising rapidly, at a rate of about 2 to 3% per year. However, the sector’s long-term goal is to halve emissions between 2005 and 2050: How can we manage without carbon offsets?

It therefore seems essential to take action on three distinct fronts: (i) the supply of SAF must surge to reach about 30% of the energy mix in 2040 and more than 50% in 2050, (ii) energy efficiency gains must exceed 2.5% per year over the next 30 years, (iii) and, in addition, a traffic restriction by bringing the growth rate down to less than 3% per year (source: IEA), which raises interesting questions about regulation—and, beyond that, about intergenerational and international equity. If all these conditions are met, the sector could become “2°C-compatible.” If one of these conditions is not met, the other two will need to be further strengthened. It should be noted, however, that this forward-looking exercise proposed by the IEA is, of course, open to criticism, given its very strong assumptions regarding technological advances (in both aviation and fuel). It does, however, have the merit of illustrating the scale of the changes needed to get on the right track. Companies in the sector must therefore give greater consideration to an ambitious roadmap for 2050, without relying primarily on a market-based mechanism (CORSIA type).

 The other skeleton in the closet: the impacts of climate change!

Global land temperatures have risen by “only” 1°C since the pre-industrial era, but the effects of climate change are already becoming very tangible. The tragic events of the summer and fall of 2018 and the extreme temperatures currently being observed in North America and Australia are just a few examples.

The aviation industry is on the front lines: traffic was disrupted in Phoenix in June 2017 due to the heat, and in Osaka for several days in September 2018 due to rising Pacific sea levels… Did you know that 25% of the world’s busiest airports are located less than 10 meters above sea level (source: Airports Council International)? Airports are beginning to take climate change adaptation seriously, but what about flight operations themselves? It’s hard to say how the increasing frequency and intensity of extreme weather events will impact air travel… on the other hand, it seems unwise not to address the issue promptly: If you haven't started yet, now is the time to do so.To learn more, read our article on the impact of heat waves on airports.

 Finally, should the industry be concerned about climate-related litigation?

Climate litigation: what is it? More than 900 so-called “climate” lawsuits have now been identified worldwide (source: Bredin Prat): climate litigation is now shifting its focus to corporations, following the first lawsuits filed against governments (the Netherlands in 2018, France in 2019). In the United States in particular, oil companies are being sued by major cities (New York, San Francisco). Inevitably, there will be damage related to the effects of climate change and, consequently, to the victims (see the IPCC’s Sixth Assessment Report). Therefore, just as inevitably, there will be legal actions to address a simple question: Who has to pay? One can imagine that after the oil majors take their first hit, they will fight back against end users of fossil fuels on the pretext that they extracted it to fulfill a request. Airlines could then be targeted, and then, in a logical sequence manufacturers, located upstream of the chain … All of this is, of course, fiction at this point, but the risk is real, and the aviation industry as a whole must give this issue the attention it deserves.