We can't all live our lives without planes in the sky, but what might we be able to change to have a lower impact? A longer read...
Let’s imagine. Up until 100 years ago, we wouldn’t have to. Commercial air travel was just beginning to take off. Package holidays were unheard of. The concept of Concord hadn’t even been thought of. And the atmosphere was far freer of pollutants, carbon, and greenhouses gases than it is today.
Any aviation innovations that would make planes less polluting are still many years away, with technical options to make flying lower carbon just not yet in existence. The easiest way to reduce emissions currently is to encourage people to fly less. However, into the 2030s, we can expect technologies such as sustainable aviation fuels, more efficient planes, and electric aircraft to play a bigger role.
If people across the world stopped flying, this could open up the door to huge changes to other, lower-carbon forms of transport. Grounding all flights on Earth would immediately put a stop to the 2.5% (and growing) of annual CO2 emissions which come from burning fuel in aeroplanes, cutting CO2 emissions by around one billion tonnes per year and eliminating a sector previously leading to rising emissions.
But flying has other climate impacts, too. Flights release non-CO2 emission, such as contrails, which are the white lines you see in the sky and the associated formation of cirrus clouds. These have a short-term, but very strong, warming impact which has been estimated as potentially tripling the overall warming effect of aviation compared to CO2 alone.
Only 11% of the global population flew in 2018, so the immediate affect of stopping flights would not be too disruptive. Air pollution levels for those living close to airports would also drop. Holidays would be more likely to be taken in people’s home countries, meaning a boost for local and national economies.
The Covid-19 pandemic brought the effectiveness of virtual and video calls to the forefront, so business flights, which cause 90% of business travel emissions, are no longer necessary. With more financial investment, virtual networking and conferencing could become even better still. Airports could be repurposed for other activities, such as hosting conferences, meetings or festivals. Grounded planes themselves could be used for unique hospitality spaces, such as hotels, restaurants and clubs
However, flying is a vital form of transportation for cargo and necessary for global trade, although some goods can be delivered by ship, lowering their carbon footprints to one-tenth or one-twentieth of their previous level, though supply chains and timelines would need huge adjustments. Ship freight of perishable food is very difficult, so there would be some return to seasonable fruit and vegetables in supermarkets. Of course, ships themselves release plenty of carbon, and a vast increase in passenger travel would be bad news for the climate. Slowing ships down is among the main short-term measures for reducing shipping emissions.
However, some air cargo is lifesaving. Air freight is used to ship medical supplies and pharmaceuticals around the world. It played a major role in delivering vaccines during the pandemic, for example. It is also used during humanitarian disasters to deliver food, water and medicines. Finding alternatives for delivering time-sensitive medicines or urgent food supplies around the world in humanitarian crises would not be easy. Additionally, many people have come to rely on flying as a relatively quick and cost-efficient way to travel long distances, and some island nations rely on flying for tourism. Millions of people around the world work in the aviation industry, and would lose their jobs.
The best alternative to aeroplanes when it comes to speed is high-speed rail – trains with average speeds over around 200km. Recent analysis from the International Council on Clean Transportation (ICCT) found that around 26% of US flights could be replaced by car, bus or high-speed rail. Another 28% of flights could in theory be replaced by high-speed rail, but are between less populated urban centres, meaning not enough people would travel on them make the investment in high-speed rail infrastructure worth it.
However, as far as investment goes, although high-speed networks wouldn't work due to high upfront costs, lower speed rail would also be a good option. The money previously spent on subsidies to airports and airlines could go instead to rolling out this rail network, although there are also emissions associated with the infrastructure. The expansion of other ways to travel would also provide new jobs for newly unemployed aviation workers, from engineers to flight attendants.
Driverless cars, once they become available, could also provide a viable alternative to
flying, allowing people to sleep or work through long journeys. However, large-scale use of
single-occupancy driverless cars – even if they are electric – would be bad news for the
climate and congestion. Carsharing could overcome this issue. Airships could meet some travel needs, but are far slower than aeroplanes, and struggle to transport many people quickly across long distances.
However, unlikely we'll ever wake up to a world without any planes. And we wouldn't want to: aviation has brought cultures together, prompted new experiences and journeys and provides urgent medicines, humanitarian aid and support for people in need.
But the huge climate impact of flying, and the difficulty in decarbonising the sector in the short-to-medium term, does raise the question of whether we should put more focus on other ways to travel, as well as avoiding travelling long-distance when we don't really need to.
Fortunately, opportunities do already exist to reduce our dependence on aviation. A focus on our own communities, local tourism and virtual meeting places, as we've already seen during the pandemic, could go a long way towards reducing the urge to fly.
In the meantime, trains provide a lower-carbon alternative to planes, and high-speed rail in particular can replace air travel, with new lines reducing aviation transport on the same routes by as much as 80%. But slower rail is just as important: sleeper trains are now having a 'renaissance' in Europe, for example, driven by passenger concern for the climate.
By 2030, the world needs to cut annual greenhouse gas emissions by around 25 times aviation’s current emissions on top of what governments have already pledged to limit global warming to 1.5C. Eliminating aviation would make a small, but still significant, contribution to closing the gap between our current emissions pathway and where we need to be.
If the aviation industry begins seriously decarbonising planes, we can ultimately hope to move to a world where zero carbon trains and planes are equally as common. For now, though, reducing flights as much as possible remains our best option for limiting the large climate impact of this sector.
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Extract from a BBC Futures article 'Aeroplanes are incredibly polluting, but could we ever live completely without them?' by Jocelyn Timperley
Illustration Ghan railway from greatrail.com