The environmental impact of Aviation

Part 1: An exploration of the industry, the status quo, and what's been tried so far

Source: Wikimedia Commons

This is the first of what will hopefully become a series of deep dives into various sources of emissions across society, trying to understand why they emit, and what the options are for cleaning them up. I chose aviation as a starting point, partly because planes have been a life-long personal passion, but also because it’s a complex industry, with a lot of competing dynamics that make decarbonising it especially tricky. It has taken an unreasonably long time to put this post together - trying to condense a lot of information into a reasonably concise narrative is, it turns out, rather tricky!

I suspected this would be a long post, and even edited down, it’s still a bit much for one sitting. Therefore it’ll be coming to you in two parts: this first part will give some background and overview of the industry, the dynamics at play, and what’s been tried so far, whilst the second will dive into the technical solutions that we could see in the future.

Intro

Aviation has long been in the eye of the climate movement, though particularly so in the past few years. The rise of the youth climate strikes, Extinction Rebellion and Greta Thunberg has led to the phenomenon of ‘flygskam’ - flight shame, where people are made to feel guilty for flying. But how bad is it - does it deserve its bogeyman reputation?

Aviation by the numbers

This is an unusual time to be writing about the aviation industry, as it is one of the sectors hardest hit by the ongoing COVID-19 pandemic and resultant lockdowns and travel restrictions. Nevertheless, pre-pandemic, the aviation industry moved around 4.5bn people in 2019, along with over 60m tons of air freight. There are somewhere north of 25,000 airliners in service, and this is only predicted to grow, coronavirus notwithstanding.

The IATA predicts a 3.5% compound annual growth rate of the industry, with passenger numbers potentially over 8bn by the late 2030s. The full impact of emissions is complex, but aviation emissions are estimated at between 2 and 2.8% of total global emissions, but the full warming effects on the planet could be as much as twice that. More concerningly, emissions themselves grew around 2% a year, despite the energy intensity of aviation decreasing by around 2.8% annually. The difficulty of decarbonising aviation, combined with its rapid growth means that it could make up 15% or more of total emissions by 2050 if action is not taken.

How aviation impacts the environment

Source: Lee et al (2020)

Aviation’s full impact on the environment is complex. CO2 is perhaps the most well understood byproduct, and as the climate metric of choice, it gets the most attention, but aircraft produce a number of other emissions that make them particularly problematic. Amongst these other emanations are nitrogen oxides, sulphur oxides, soot and water, each of which have different effects. Nitrogen oxides, for example, reduce methane (a greenhouse gas) producing a cooling effect, but increase ozone, which has a heating effect.

Some of the largest effects are from ‘contrail cirrus’. These are high level clouds that sometimes form from the contrails aircraft leave in their wake. They can persist for up to 18 hours, and whilst they reflect some solar radiation, they also trap heat, resulting in a net warming effect. The impact of this is still being quantified, but studies put the radiative forcing effect of aviation contrails today as greater than that of the CO2 released from all powered aircraft throughout history.

Many of the emissions from jet engines also are produced by ground transport, but as jet airliners spend the majority of their time cruising at high altitude, these emissions are released directly into the upper atmosphere, where their effects are more pronounced.

Impact of COVID-19

Given the severity of the coronavirus pandemic, and particularly its effect on travel, it’s worth briefly looking at how the aviation industry has been affected. International travel has plummeted, and many airlines, which tend to run on razor-thin margins, required bailouts from their respective governments. Largely these bailouts have been condition-free - the US, Germany and the UK all placed minimal or no conditions on airlines receiving handouts. France was a rare exception, making its bailout of AirFrance conditional on the airline improving its environmental footprint, stipulating that it would need to reduce emissions and phase out flights competing with domestic high-speed TGV rail services.

Despite the dire state of passenger travel, air freight has continued, and indeed has played a vital role in keeping vital medical supplies such as PPE flowing across the globe throughout the pandemic. A number of airlines have temporarily repurposed their passenger aircraft for freight, filling seats with parcels in place of people in a bid to keep money flowing as passenger counts fell.

The pandemic has undoubtedly changed how many view air travel, with many businesses reviewing the need for business travel in particular, realising that in fact many interactions can be conducted remotely. Whilst tourism demand is likely to remain low for some time due to concerns from the public and government restrictions, not to mention financial insecurity for many, it will likely rebound in a year or two, and there is little sign that the crisis has dampened general enthusiasm for foreign travel.

Why are planes hard to decarbonise?

The decarbonisation of aviation is a multi-dimensional problem. The technical problem itself is extremely challenging due to the nature of flight, which I'll explore more in part 2, but as with many industries, there are other forces at play.

Politically, aviation is complex - it bridges borders and is a connecting force worldwide. Not only is it almost by nature an international problem, it also drives a huge volume of trade and tourism, both key economic forces. This means any conversation about aviation gets complex, fast. Everyone has an opinion and wants a say, and all it takes is one player not playing ball to scupper an international agreement.

The industry itself also brings its own challenges to the table. Flight is inherently more risky than ground transport - if something goes wrong the stakes are far higher - so preventing issues is a primary concern. Regulation and certification of aircraft is a hugely complex and involved process - it can take years and hundreds of millions of dollars to certify a new aircraft for flight. These high standards have pushed the safety of air travel to extremely high levels, with accidents not only extremely rare, but far more survivable than ever before.

These safety requirements also push strongly towards the known over the unknown. As an example, if you’ve flown a domestic or short-haul flight, chances are high that you flew on some variant of either a Boeing 737 or an Airbus A320, both of which were first introduced over 30 years ago (the A320 family launched in 1984, and the 737 first flew in 1967!). These aircraft have been regularly updated and improved over the past several years, but the core designs and basic airframe have not changed in all that time - certifying an update to an existing airframe is significantly simpler than getting approval for a clean sheet design.

Certification and regulation along with ever more cutting edge engineering has also pushed costs of aircraft development higher and higher. This changes how successful an aircraft programme must be - aircraft need to secure ever larger portions of the market to pay off the costs of development, meaning there is room for fewer and fewer players. These forces took the market from dozens of airliner manufacturers in the 50s and 60s to just two main players today.

The short- and long-haul airliner market is now essentially a duopoly between Boeing, a vast US aerospace and defence company, and Airbus, a similarly large entity from Europe. Both have close ties to their respective geographic regions, and roughly split the commercial aviation market in two. There are a few manufacturers of smaller aircraft, such as Bombardier and Embraer, but by and large if they compete with the big two, they get bought out - Airbus took a large stake in Bombardier’s C-Series regional airliner program, and Boeing was until recently in talks to buy a majority stake in Embraer’s entire commercial aircraft program. China and Russia have airliner programs, but Russia’s is part of a vast state-owned industrial complex mired in bureaucracy, and China’s is still in its infancy.

Even with the gigantic scale of these companies, the costs of airliner programs continue to spiral upwards. The Boeing 787, one of the few clean-sheet designs in the last couple of decades, cost an estimated $32bn to bring to production, and was delayed for multiple years. Boeing has been very cagey about profits and revenue from the program, but numerous analysts have suggested that the program will likely never make a profit, even after selling a thousand or more aircraft. All this for an aircraft that, whilst innovative, is still remarkably similar to the basic tube-with-wings design that has been the norm for half a century or more.

Finally, it is worth considering the role of airlines in the market - as the primary customer for airliners, their demands in many ways dictate the market. Airlines are squeezed at both ends, facing enormous capital costs - aircraft, fuel, maintenance, crew, flight/landing fees - and a competitive market where ticket prices are being forced ever lower. The famous Richard Branson quote, “If you want to be a millionaire, start with a billion dollars and launch a new airline”, is very apt. Airlines are a very hard business to make money in, and they are thus extremely risk-averse when it comes to new designs - they would almost universally take a safe design over a risky innovation.

All these factors combine to make an industry that is hard to regulate, inherently tied up with geopolitics, immensely expensive, slow moving and incredibly risk averse.

What has been tried

Solutions largely fall into three different camps - technical improvements, offsetting carbon emissions, and trying to limit flying.

Technical improvements have driven significant improvements in aviation. As I mentioned earlier, the energy intensity of aviation has fallen by around 2.8% annually, driven largely by cost and noise factors. Ever tightening noise regulations have forced out older, louder jets, and the hunt for cost savings has driven a push for more fuel efficient planes. Environmental factors are starting to influence technical choices, and may have a larger influence on future new aircraft designs, but for now, cost and noise are the primary drivers for improvement.

Unfortunately, the progress that has been made has been more than offset by huge growth in passenger numbers, meaning that overall, emissions have still increased. There is also concern from some industry figures that efficiency gains are reaching their limits for current aircraft designs, and that further gains will cost more for smaller improvements. The other problem with improving by increasing efficiency is, as Saul Griffith aptly puts it, “You can’t efficiency your way to zero”. To radically reduce or eliminate emissions will require a step-change in technology - something that is not only technically challenging but that the industry is extremely averse to.

Given the lack of achievable current technical solutions, industry and regulators have turned to two principal tools to mitigate their emissions - offsetting and sustainable fuels. This suits both airlines and aircraft manufacturers well, as it allows them to make visible efforts to appease environmentalists without fundamental changes to their business models or the aircraft themselves.

Offsetting

Carbon offsetting is the name for balancing emissions from one source with removal or mitigation of emissions elsewhere. They work on the concept that the atmosphere is a shared resource, so in theory, a ton of carbon is roughly equivalent to any other ton of carbon, no matter the source nor sink. It’s a complex and nuanced topic that is well beyond the scope of this post, but it’s something I’ve written about before, and may look at again in future.

So, efficacy aside, how do offsets work in the world of aviation? Until the last couple of years, the responsibility was almost entirely on consumers, who would have to calculate the emissions of their flights, find an offset provider, and pay themselves. In recent years, tools and top-level aggregators have appeared to make the task easier, but airlines have mostly avoided the blame.

That has changed in the last year or two, with various airlines offering options to offset flight emissions when buying tickets, and this year, Easyjet, the UK budget airline, decided to offset all of its flights from 2020. Others will likely join them soon - more and more airlines are making commitments to reduce or zero out their emissions. As consensus builds internationally on climate action, industry and governmental efforts to reduce emissions will likely grow, and with few tools at their disposal, offsetting is likely to be the weapon of choice.

SAFs

I’ll explore sustainable aviation fuels (SAFs) more fully in part 2, but there are some options for reduced carbon fuels available already. These are mostly biofuels that have some certified reduction in carbon impact over traditional fossil aviation fuels. Biofuels are another complex topic in themselves, and the subject of heated debate due to the complexities of changing land use from either natural ecosystems or food production to grow the feedstock for the fuels.

Regulators have been cautious in adopting SAFs, approving increasing mixes of SAFs and regular kerosene, but takeup has been limited so far. Much of this has to do with the limited availability and high price of sustainable fuels thus far, but may change with more and more airlines making commitments to purchase and use the fuels as environmental impact becomes a higher priority.

Politics

So what about political solutions? The international nature of aviation makes sweeping political agreement complex - 65% of CO2 emissions from aviation are in international airspace, so don’t ‘belong’ to individual nation states. For this and other reasons, aviation was explicitly excluded from the scope of the Paris Agreement. Nevertheless, there have been a number of attempts to regulate aviation’s environmental impact, with varying success.

The EU made probably the first major attempt to regulate aviation emissions as part of its emissions market - the EU Emissions Trading Scheme (ETS). In 2008, the European Parliament voted to include aviation in the ETS from 2012, which would cause all flights into, out of and within Europe to be logged and counted against airlines’ carbon quotas. However, the airline industry, along with countries such as the USA, China, India and Russia reacted strongly against the move. The US even threatened to ban their national carriers from complying with the scheme. The EU eventually put the inclusion of international aviation in the ETS on hold for the indefinite future, although it did still cover flights within the EEA.

In 2016, the UN body responsible for aviation, the ICAO, finalised an agreement between 191 countries to take responsibility for aviation emissions. This scheme is known as CORSIA - the Carbon Offsetting and Reduction Scheme for International Aviation (aviation does like its acronyms!). One of its main aims was to achieve the ICAO goal of making all growth in aviation after 2020 carbon neutral. It enforces measuring and reporting of all aviation emissions by member countries. Airlines must offset all emissions over the baseline year (originally 2020, now renegotiated to 2021 after the precipitous drop in aviation traffic due to COVID-19).

The scheme will start in 2021, and is a voluntary pilot until 2023, covering all airlines with international emissions above 10,000 tons of CO2 per year. There will then be a phased transition to the full scheme, which will be mandatory from 2027. Currently the scheme is only agreed on until 2035 - a point of concern, as if it is not extended further, it will only cover around 6% of projected CO2 emissions from international aviation between 2015 and 2050.

Various countries (mostly in Europe) have implemented some form of aviation tax, often in the form of a distance-based charge on tickets, but approaches are fairly piecemeal at present, and subject to heavy pushback from airlines. The additional financial pressure imposed by the COVID-19 travel restrictions has also given airlines another reason to resist efforts to implement taxes. As with many environmental measures, taxes and policy tools are likely the biggest levers to enact change, but they are slow, and easily stymied by savvy aviation lobbying bodies.

Flygskam

Lastly, there is the most manual solution - fly less. There will always be a need for flying, whether for business, visiting family, goods transport, or countless other reasons, but modern flights are so cheap and easy that many of us indulge more than we should. Flygskam has become a well-recognised phrase in climate circles, meaning ‘flight shame’. Not flying at all is the most radical solution, but as with all such measures, absolutism isn’t as important as reduction - flying less will still have an impact. Frequent Flyer taxes have been touted as a potential solution - in the UK a mere 15% of the population take 70% of all flights.

Not flying in many places doesn’t have to limit travel either. Whilst some journeys will always be out of reach of all but the most determined non-flier, trains are a good alternative in many parts of the world. Europe has significant high-speed rail coverage, and whilst its systems are rather disjointed at present, efforts by retailers like TheTrainLine and RailEurope are helping to bridge these gaps. Night trains in particular are making a come-back in recent years across the continent, offering trips where the journey is part of the experience rather than just a means to travel from A to B. Resources like Seat61 also help to demystify some of the complexity of booking longer journeys by rail across the world.

Looking to the future

That brings us to the end of our tour through the current state of aviation. Now, you may be forgiven at this point for thinking that the future of aviation looks rather bleak - political solutions lack teeth, and the only options to reduce the impact of flying are to offset (with all that that entails) or not to fly. However, fortunately, that’s not the case. There are a host of technologies that have the potential to reduce or eliminate the emissions from flight. While the industry might be cautious to adopt them, they do exist, and that’ll be the subject of part 2, which hopefully will be winging its way to you next week.

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