Why air travel is more sustainable than you think

The climate challenge is immense and the aviation industry often shoulders much of the blame. But rapid progress is being made towards more sustainable flying

September 18, 2019
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Protestors disrupted air traffic at Heathrow, by flying drones to bring attention to climate change. Activists were willing to break the law in order to get their message heard. One of those arrested claimed that “any disruption that might be caused to travelers is nothing compared to the imminent climate breakdown we are facing.”

This is just one example in a line of recent events designed to raise awareness about the environmental impacts of flying. Climate activist Greta Thunberg made a point of not flying to New York for the UN climate summit, instead opting to sail across the Atlantic. Her home country of Sweden has even invented a word for the feeling of shame you may have if you travel by air: flygskam.

There’s a push for aviation fuel to be taxed, and international flights out of France have already had a tax applied to them. The idea being that increasing the cost of flying will curb demand and people will find alternative means of transport, or simply not travel at all. However, research from Bright Blue shows scepticism among the public for demand-curbing measures such as these.

Happily, they may not be needed. Climate change is a challenge of immense importance and of course aviation must play its part. The industry has rightly been tasked with cleaning up its act. But is flying really as bad for the environment as you think? I would argue not. And indeed, efforts are underway to improve things further.

Contrary to what many believe, global aviation only contributes 2 per cent of greenhouse gas (GHG) emissions worldwide. That is still too high, but the industry aims to reduce net emissions by 50 per cent by 2050.

After speaking to several professionals across the sector, it is clear that there are a number of initiatives being taken to reduce the carbon footprint and bolster sustainability.

Just like road and rail networks, airspace networks need to be maintained and upgraded. Except UK airspace has not undergone significant changes since the 1950s. Outdated flightpaths often constrain aircraft from reaching their optimal cruising altitude more quickly, resulting in increased inefficiencies, greater fuel burn and subsequently more GHG emissions.

The good news is that there is now a major, government-backed programme of airspace modernisation which will enable aircraft to climb and descend much faster, as well as put an end to flight “stacking,” where aircraft are put into a holding pattern during times of air traffic congestion. A spokesperson for the UK Civil Aviation Authority said: “Where aircraft are able to follow more fuel-efficient routes, wider society will benefit because fewer Co2 emissions will reduce greenhouse gas impacts.”
“Today’s aircraft are 80 per cent more fuel efficient per passenger km than the jet aircraft of the 1960s”
Carbon offsetting is another initiative being used. The International Civil Aviation Organisation’s Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is the first ever global sectoral agreement to introduce carbon pricing, based on the goal of capping net emissions at 2020 levels to ensure carbon neutral growth from 2020 onwards. Airlines subject to the agreement will monitor and record their fuel usage on international flights. When total emissions covered by the scheme go above the baseline, calculated as average emissions between 2019 and 2020, they must be offset.

Airlines purchase an offset essentially by buying a carbon credit that has reduced emissions elsewhere. The offset cancels out their own emissions, and cannot be sold or purchased again.

There have been concerns in the past that offsetting harms others. “Offsetting emissions, which is the main measure of CORSIA, doesn’t deliver real emissions reductions and often leads to land conflicts,” explains Magdalena Heuwieser from Stay Grounded, a network that consists of more than 130 organisations around the world countering aviation and global warming.For instance, forestry credits have forced indigenous South American tribes from their land to make way for tree plantations.

However, CORSIA rectifies this by stating that offsets must “do no net harm.” Currently, the scheme is only applicable to international flights going between one country which has ratified CORSIA, to another. As it stands, there are 68 countries covered. The UK government could drive aviation sustainability globally by encouraging more states to sign up, which will prevent “carbon leakage”—carriers transferring their operations to other countries with more relaxed emissions constraints.

The use of Sustainable Aviation Fuels (SAF) is another encouraging innovation. Biofuels are one example. Derived from plant materials and typically mixed with conventional aviation fuels, biofuels are a fossil fuel substitute in use since 2008. Admittedly, the debate has been a controversial one, as a major downside to biofuels is the amount of land required that could otherwise be used for food production. To meet current demand for aviation with plant-based biofuels, arable land the size of Australia would be required, 7.6m square km to be exact. “Alternative aviation fuels include palm oil, with devastating effects on the rainforest and the climate,” says Heuwieser.These concerns are worth taking very seriously. Fortunately, there are SAFs which aren’t created using large swathes of arable land and whose production does not have such pronounced negative side-effects.
"Some new aircraft use less than three litres of jet fuel per 100 passenger kms, matching the efficiency of modern compact vehicles"
UK airlines are at the cutting edge on SAFs. British Airways’ waste-to-jet fuel programme will take over half a million tonnes of non-recyclable household and commercial waste that is destined for landfill and convert it to sustainable jet fuel. In doing so, it will deliver a net 70 per cent reduction in GHG emissions for every tonne of conventional aviation fuel it replaces. Virgin Atlantic has embarked on carbon capture and utilisation (CCU) as a form of SAF: CCU recycles existing waste carbon to create fuel. Virgin Atlantic trialled its first flight powered partly from recycled waste carbon, sourced from waste gases, in 2018. SAFs could offer up to a 24 per cent reduction in Co2 from the UK aviation sector by 2050. Currently in the UK, there are limited facilities to test and approve new fuels, therefore it takes place in other countries instead.

By renewing their fleets with modern aircraft, airlines increase fuel efficiency and decrease GHG emissions. As a result of purchasing new aircraft, Sustainable Aviation member airlines, which include major carriers such as British Airways, easyJet, Tui and Virgin Atlantic, have improved their fuel efficiency by 12 per cent since 2005—saving 20m tonnes of Co2. New aircraft, such as the Airbus A380, Boeing 787, ATR-600, Embraer E2 and Bombardier C-Series aircraft use less than three litres of jet fuel per 100 passenger kms, matching the efficiency of most modern compact vehicles. In addition, the retrofitting of winglets onto aircraft—which break up vortices and subsequently reduce drag—has saved 80m tonnes of Co2 since 2000. Today’s aircraft are 80 per cent more fuel efficient per passenger km than the jet aircraft of the 1960s, and new aircraft developed in future will only continue to make even greater fuel savings.

Such future aircraft may even abandon combustion technology entirely. Benjamin James, a New Zealand-based aircraft engineer stated that “in the medium-longer term future, hybrid and electric propulsion systems will also begin to play a role in the commercial aircraft market, bringing significant reductions in aviation greenhouse gases.”

The story of sustainable aviation is one not frequently told in today’s headlines. And of course there remains a long way to go. But through airspace modernisation, carbon neutral growth post-2020 thanks to CORSIA, SAFs, modern fuel-efficient fleets and future propulsion systems, the aviation industry does at least seem to be taking its commitment to GHG emissions reductions seriously. Perhaps next time you fly you won’t suffer from so much flygskam.

Patrick Hall is an Energy and Environment Policy Researcher at the Bright Blue think tank