If “sustainable” means to sustain activity over and over, then the verdict for flying looks bleak. To avoid the most catastrophic consequences of the climate crisis – for example, displacing over 680 million people in low-lying areas – the Intergovernmental Panel on Climate Change (IPCC) states that we need to halt global warming at a 1.5-degree rise. To do this, we need to reduce global carbon emissions by approximately 6 per cent each year. Incidentally, this is roughly what was saved when the world was grounded during Covid-19.
Meanwhile, if we look back to the pre-pandemic days of 2018, when luggage allowance was the only barrier to whizzing over to Barcelona for tapas for £50, we might be forgiven for thinking that everyone was at it. But, in reality, only 5 to 11 per cent of the world's population flew. In fact, a staggering 1 per cent of frequent fliers were responsible for half of all carbon emissions from aviation. So, while aviation's global share of carbon emissions is, at 2-3 per cent, relatively small; it's benefiting a tiny proportion of the worldwide population. The predicted growth also rings alarm bells: the International Civil Aviation Organization forecasts that emissions from flying could increase by as much as 700 per cent by 2050 (mainly due to a growing middle class in Asia). If these predictions are realised, flying will be responsible for a global surge in carbon emissions.
On an individual level, sustainable flying doesn't quite stack up either. If we divide the IPCC's estimated global carbon budget per person, we get a carbon allowance of 2.3 tonnes of CO2 per year. Before even considering heating a home, eating or commuting, a round-trip by plane between the US and Europe equates to 4.3 tonnes of CO2 per person.
While the aviation industry still depends on fossil fuels, flying simply isn’t a sustainable mode of transport. However, if aviation can make the shift to clean tech, we might be able to talk about sustainable flying.
Several renewable approaches are in the pipeline, and, unsurprisingly, the industry is optimistic about innovating itself out of the carbon conundrum. Sustainable Aviation Fuels (SAF) have shown promising results for some airlines. For example, KLM reduced single flight emissions by up to 75 per cent using SAF, which can fuel existing planes. However, the sheer scale needed makes SAF unfeasible in the long term. Green hydrogen is also being explored by the likes of Boeing but is a long way from mainstream use.
Hybrid-electric planes offer more hope, but the weight and cost of batteries are still prohibitive. One of the most significant successes to date has been the nine-seater hybrid-electric plane eCaravan that completed a 30-minute flight in Washington in 2020. Meanwhile, Norway has committed to only using electric aircraft for short-haul flights by 2040, and easyJet has partnered with Wright Electric to fly a 180-seat fully electric jet 500km by 2030.
Elsewhere, several promising innovations are yet to be fully tested: for example, shifting routes to avoid the damaging non-carbon impact of contrails, which produce water vapour, aerosols, and nitrogen oxides, and using Big Data and AI to make global air traffic control systems more efficient.
For now, though, it's up to us to limit our impact as best we can. Here’s how best to do it when you have an essential flight to catch.
A first-class ticket on a long-haul flight emits approximately four times as much carbon as an economy seat. And, in fact, if you plump for a budget airline with one class of travel where the load factor (in layman’s terms, how full the plane is) is high, you’ll cut your carbon footprint even more.
Connecting flights not only travel a much greater distance than direct flights, they create more emissions on take-off and landing (approximately 25 per cent of a flight's overall emissions). Opting for direct flights is always more efficient. Once in a destination, avoid hopping around by plane and instead look for overland options – public transport is nearly always the most carbon-efficient way to get around.
Be aircraft savvy
As a general rule, the newer the aircraft, the fewer the emissions, so look out for the planes such as the Airbus A320neo and Boeing 787 Dreamliner. Boeing claims that its Dreamliner uses 20 per cent less fuel per passenger than the older planes it replaces. According to Airbus, CO2 emissions from aircraft built today are 80 per cent lower than those from the 1970s.
The International Council on Clean Transportation suggests that it's best to avoid very small or very large planes, which tend to be less efficient than a standard single-aisle or small twin-aisle aircraft.
After mapping the fuel use of 13 carriers on transatlantic routes, the OAG (an air travel intelligence company) found that the most efficient airline, Aer Lingus, has almost half the carbon footprint of the least efficient, Air France.
German non-profit Atmosfair produces an annual index of the CO2 emissions for each airline you can check, although the 2020 report has been delayed due to Covid-19.
The less weight, the less fuel needed; packing light isn't going to save the planet but every little helps.
Support ‘greener’ airlines
Greenwashing is rife, so be wary of “Most Sustainable Airline” claims on the back of banning plastic straws or getting customers to bring their own headphones. However, incremental changes do stack up, so it would be churlish to ignore them altogether.
Waste is a huge issue for aviation. Just think of all those single-use, individually wrapped utensils, for starters. According to the International Air Transport Association (Iata), airline passengers generated 7.3 million tons of waste in 2018. Look for sturdy commitments to reducing plastic, reducing weight, offering vegan and vegetarian menus, and reducing food waste. For example, JetBlue has a food composting facility at JFK Airport, easyJet is investing in lightweight Recaro seats, and most major airlines have committed to eliminating single-use plastic in some form.
In 2019, after discovering that it uses 27 million single-use plastic coffee lids every year, Etihad replaced 95 different single-use plastic items to complete the world's first-ever single-use plastic-free long-haul flight. It's yet to be seen whether this will result in a long-term change or whether it was just a PR stunt.
Offset your carbon
Sadly, the wonderful notion of offsetting whereby we can emit carbon via flying and pay to absorb carbon elsewhere (for example, by tree planting) is fraught with problems. That 6 per cent reduction in global emissions isn't going to happen if we aspire to absorb what we emit; we need to reduce overall carbon emissions. The offsetting industry is also rife with dubious claims and calculations. For example, many schemes focus on mono-crop tree planting rather than protecting existing forests or other dense ecosystems, which are more productive carbon sinks.
However, if you are going to fly, on balance it’s better to do something than nothing – but don’t just use the airline’s paltry add-on of a couple of quid to assuage your conscience. Research offsetting schemes that are fully transparent, third-party verified,provide additional carbon savings, provide sustainable economic opportunities to communities, and go above and beyond the cheapest possible carbon offsets. Protecting or regenerating existing ecosystems is better than monoculture tree-planting. Use an accurate calculator (such as Atmosfair’s) to work out how much you need to offset by, and be mindful that climate experts agree that negative environmental impact from flights is multiplied by other toxic gases like nitrogen oxide and altitude.
Make it count
We can make our flying habits more sustainable by taking fewer trips and making every trip count. The travel industry has the potential to protect fragile ecosystems by providing the alternative income needed to help countries and communities move away from more destructive industries like fishing, mining, construction and large-scale farming. However, there’s no quick win. Genuinely making it count means scrutinising where you go – and where your money goes – to ensure you don’t add another dollop of environmental harm on top of your flight emissions.
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