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The UK government is set to back plans for a third runway at Heathrow, the country’s busiest airport, and to expand two other airports near London: Gatwick and Luton. The move is designed to support the government’s “mission” to grow the economy.
Air transport is notoriously hard to decarbonise. Unlike the energy system, or even road transport, there is no renewable alternative to switch to immediately. If electric or hydrogen planes become reality, it won’t be for many years yet. Therefore it’s not clear this airport expansion can fit within the UK’s legal and arguably moral requirement to cut emissions and remain within its carbon budget.
It certainly goes against what the government’s official advisory body the Committee on Climate Change (CCC) recommends. The CCC’s 2023 report to parliament stated that: “No airport expansions should proceed until a UK-wide capacity management framework is in place to annually assess and, if required, control sector GHG [greenhouse gas] emissions and non-CO₂ effects.”
Those non-CO₂ effects of aviation include water vapour, soot and other gases like nitrous oxides and sulfur dioxide, all released directly into the high atmosphere where they help form heat-trapping clouds. Estimates suggest they could triple the greenhouse impact of aviation.
In 2019, the last year of available data pre-COVID, domestic and international aviation accounted for around 8% of the UK’s total emissions. The non-CO₂ effects makes aviation a larger contributor to climate change than that number suggests.
The sector itself struggles to build a coherent decarbonisation roadmap based solely on “supply-side” improvements to things like fuel efficiency or, in a recent example from EasyJet, thinner paint. The demand side – taking fewer flights, frequent flyer levies, or restrictions on domestic flights as have been introduced in France – is rarely mentioned.
Unfortunately aviation is a prime example of the Jevons effect where any improvement in efficiency has been wiped out by increased demand. With a growing global middle class pursuing a higher consumption lifestyle, aviation emissions continue to grow even while other sectors have shows some efforts to reduce their own.
The UK has mandated that synthetic aviation fuel (SAF), a more sustainable alternative to regular jet fuel, must make up 10% of aviation fuel by 2030. But only 1.2% of aviation fuel is currently SAF and the industry has not published any plans to show it can scale up in time. Indeed, the sector’s own plans for growth will outstrip efforts to decarbonise through synthetic fuel, delivering a neutral effect at best.
The consumer-facing airport sector has also been accused of greenwash. For instance, Luton Airport recently published adverts making the claim that its own expansion would be stopped if it did not meet stringent environmental targets. However, the Advertising Standards Authority found that consumers would naturally believe that would include air traffic and not just terminal operations (a terminal’s heating or lighting is, of course, largely irrelevant when its core business is as emissions-intensive as flying).
The difficulty of decarbonising aviation while the sector still grows is exemplified by the government’s recently launched consultation on adopting the Corsia carbon offsetting scheme for international flights and how it might work with existing cap and trade schemes. All of which encourage or excuse excess emissions through a charging mechanism.
Growing pains
“Kickstarting economy growth” and “Make Britain a clean energy superpower” are two of the UK government’s six “missions”. However, by expanding airports in support of the former, it risks failing the latter.
A new report by thinktank the New Economics Foundation shows that airport expansion could balance out all of the emissions saved by the government’s clean power plans by 2050.
There is evidence that airport expansion can bring some of the economic benefit that government needs. However, another New Economics Foundation report has found that air travel is no longer a catalyst for productivity growth. So the economic benefits of a new runway are really confined to the airport operation itself – projects for engineers and builders, service jobs for people living near Heathrow, and so on.
Aviation is the privilege of the richer part of society, both globally and within the UK. Figures from Our World in Data shows the richest 50% of the global population produces 90% of the aviation emissions.
While many more UK residents have experienced flying than in the past, most flights are still taken by a small, wealthy subset of the population, which will typically capture the largest share of any new capacity. Each year, around half of British residents do not fly at all.
The focus on London airports for the largest scale expansions will shift the balance of the economy further towards south-east England, and increase inequality within the UK economy. And while these plans might bring some of the GDP gains the government is desperate to deliver, all the evidence shows they will be at the expense of its environmental targets.
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Richard Sulley receives funding from the Grantham Foundation for the Protection of the Environment
