Can flying ever be green?

Our verdict at a glance

It’s unlikely that flying will ever be green, or at least not for many decades, because the technologies are currently just speculative at the scale needed. So, the best and only realistic option right now is to reduce flying. This requires more ambitious emissions cuts, an end to airport expansion and better alternatives to air travel.

How does flying affect the environment?

Many of us love to travel and explore more of our beautiful planet. But while flying is a popular form of transport, it has a significant negative impact on the climate and the environment. 

The carbon footprint of flying

In 2023, flying made up around 8% of UK emissions, largely due to international flights. This might seem relatively small, but despite a significant drop during and immediately after the Covid-19 pandemic, flying is on the increase.

Between 2000 and 2024, the number of passengers grew by more than 60%. And passenger numbers will have more than doubled by 2050, even if the advice from the Climate Change Committee (CCC) – the government’s independent advisor – to constrain growth is followed. By 2050, aviation will likely be the second biggest UK emitter after agriculture, responsible for 35% of emissions if the CCC’s recommendations are followed – or a much greater proportion if they aren’t.

Worldwide, most people fly rarely, if ever. In the UK, 10% of people are responsible for almost half of all flights. There’s also a big wealth disparity. In 2023 for example, over 70% of low-income households didn’t fly at all, whereas 20% of households with the highest incomes flew 4 or more times. These wealthy frequent flyers have a very large carbon footprint. That’s because flying is one of the most carbon-intensive activities we can do. For example, taking one return flight to New York would generate more carbon dioxide (CO₂) emissions than driving a car for a whole year.

Flying and other emissions

It’s not just carbon emissions impacting the climate. Aviation produces nitrogen oxides, sulphur dioxide, soot and water vapour, which also contribute to global heating. The science is imprecise, but it’s estimated that this increases the harm caused by flying by as much as 3 times. Although these impacts are relatively short-lived compared with CO₂, they must still be taken into account.

Air pollution and other environmental impacts

Air travel has other environmental impacts. These include noise and air pollution, as well as the sizable amount of land taken up by airports. This affects people’s health, wildlife and biodiversity.

It’s been estimated that global air pollution from aviation causes 74,300 premature deaths each year. Alongside habitat loss, noise and light pollution from airports can severely disturb animals in the area, making it much harder for them to breed or communicate with each other. And many airports will actively manage and deter local bird populations to prevent bird strikes.

Can flying be environmentally friendly?

It’s true that planes are gradually becoming more efficient, reducing emissions per passenger. But this isn’t happening fast enough to match the growth in flights, so overall emissions are still increasing. And there are no easy solutions from alternative technologies or approaches either.

Sustainable aviation fuel

There’s a lot of talk about sustainable aviation fuel (SAF), which currently uses biofuels (made from waste) or e-fuels (made using electricity) to power aircraft, rather than fossil fuels. In 2024, a transatlantic flight powered by 100% SAF reduced its CO₂ emissions by over 60% and non-CO₂ emissions by 40%. Sounds promising, right?

The problem is that there’s currently no sustainable way to produce enough SAF at scale using only waste materials. So, it’s likely that crops like maize and palm oil would be used, potentially requiring vast swathes of land. Even without aviation, crops are already one of the main causes of deforestation. Biofuels also risk competing with food production, making water scarce and displacing communities.

And while e-fuels might sound like a better option, they’ll require a lot of renewable energy to produce, at a time when we need it to replace fossil fuels in electricity generation, transport and heating.

We do need investment in these fuels, including innovating to make them cheaper. But realistically they won’t be available at scale for decades, so at least until then we need to constrain aviation use.

Carbon offsetting

Carbon offsetting supposedly allows individuals, companies and countries to make up for the carbon emissions they’ve caused by paying for projects that remove emissions from the atmosphere. For example, some airlines will encourage passengers to pay for tree planting to offset their flights. The International Civil Aviation Organization has also adopted a carbon offsetting scheme for airlines.

But in most cases carbon offsetting doesn’t work. The amount of CO₂ it’ll save is often overestimated, and a project’s impact can take a long time to be felt or not last long enough. Ultimately, carbon offsetting distracts us from what’s most urgent and effective – actively reducing emissions.

The CCC has recommended that the aviation industry pays for carbon removal using Bioenergy with Carbon Capture and Storage (BECCs). The Drax power plant in Yorkshire currently burns trees to produce electricity and plans to capture the carbon from the chimney stack and store it under the North Sea – an example of BECCs.

But the plant has been mired in controversy due to the harm to nature from its logging activities in the USA and for the impacts on communities living near its wood chipping facilities. Relying on this approach and a technology that’s not yet in operation to allow for aviation to expand is premature and reckless.

How can we reduce the environmental impact of air travel?

More ambitious targets and measures for aviation

The previous government set a trajectory for UK aviation emissions in its 2022 Jet Zero Strategy, from 35 million tonnes of carbon dioxide equivalent (MtCO₂e) in 2030 to 28 MtCO₂e in 2040 and 19 MtCO₂e in 2050. The Climate Change Committee has since recommended emissions are reduced to 23 MtCO₂e by 2050. Current emissions are 33 MtCO₂e.

But these targets aren’t binding, and there isn’t yet a clear plan for how they’ll be met. They also don’t address non-CO₂ effects. Steeper reductions are likely to be needed if the UK is to deliver its economy-wide climate targets and international obligations.

Measures to reduce emissions include removing tax breaks on aviation fuel and limiting the numbers of flights at airports. 

Stop airport expansion

Several airports across the UK are looking to expand. And the government has recently said it’s in favour of giving airport expansion the green light in the name of growth. It’s officially announced it’s “minded” to grant Gatwick the planning permission it needs, and it continues to make supportive noises about Heathrow.

But we need fewer flights and emissions, not more. Any growth will largely be enjoyed by wealthy shareholders and frequent flyers. The government must stop all plans for airport expansion.

Discourage flying and encourage alternative travel

Flying shouldn’t be dominated by a wealthy few. A frequent flyer levy would tax people’s additional flights – the more they fly each year, the higher the levy. Increasing the cost of frequent flying should lead to fewer flights. And curbing the number of flights taken overall would still allow people to enjoy an overseas holiday if flying was distributed more evenly.

Businesses should limit flying as much as possible. Flights for business purposes fell by almost a third in 2023, and this trend should continue in a post-pandemic, Zoom-savvy world.

Governments and transport companies also need to incentivise alternative methods of travel. Long-distance train journeys, for instance, are a great way to explore Europe, but public transport needs much greater investment to make these journeys affordable and better value for money than flying.