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The only way to hit net zero by 2050 is to stop flying

Climate change

The only way to hit net zero by 2050 is to stop flying

Dreaming of electric planes and planting trees will not save our planet

© Toby Melville/Reuters

The writer is professor of engineering and the environment at Cambridge university

The UK aviation industry this week promised to bring its net carbon emissions down to zero by 2050 while growing by 70 per cent, and Prime Minister Boris Johnson boldly predicted that “viable electric planes” would be available in just a few years.

But past experience with innovation in aviation suggests that such ambitious targets are unrealistic and distracting. The only way the UK can get to net zero emission aviation by 2050 is by having a substantial period of no aviation at all. Let’s stop placing impossible hopes on breakthrough technologies, and try to hit emissions targets with today’s technologies. Our recent report “Absolute Zero” draws on work at six British universities to explain how.

There are three ways to deliver net-zero aviation: invent new electric aircraft, change the fuels of existing aircraft or take the emissions out of the atmosphere.

Electric planes already fly. Solar Impulse 2, powered by solar cells flew one person round the world in 2016, but slow progress in photovoltaics mean this is unlikely to scale up. Demonstrations of short battery-powered flights with a few passengers will soon begin. However, the technology is in its infancy and aerospace is, rightly, a highly regulated industry. Commercial long-haul electric flights will not be operating at any significant scale by 2050.

Alternative fuels, such as hydrogen or synthetic kerosene, only deliver zero emissions flight if their production is powered by renewable electricity. Right now, green sources supply about 15 per cent of the world’s primary energy consumption. Over the next 30 years, while road vehicles, heating and industry are being electrified, there is unlikely to be spare clean power to make aviation fuel.

Finally, there are currently no meaningful negative emissions technologies. It requires more energy to recapture carbon dioxide from the atmosphere than was generated when it was released. Using renewable electricity to power carbon capture rather than to displace fossil fuels does not create a net reduction. And tree planting only goes so far: we must increase the total area of forest in perpetuity to produce a one-off reduction in atmospheric carbon dioxide.

So the commitment to net zero aviation by 2050 is really a commitment to zero aviation. Rather than hope new technology will magically rescue us, we should stop planning to increase fossil-fuel flights and commit to halving them within 10 years with an eye toward phasing them out entirely by 2050.

Taxing aircraft fuel at the level of the UK’s current road fuel tax would be a useful first step: I estimate that it would make flights up to four times more expensive.

Climate policy announcements so far have failed to account for the limited rate at which new technologies can reach significant scale. Fifty years after the Danes began developing wind turbines, they contribute just 2 per cent of world primary energy. Regardless of prices or incentives, new energy generation, transport and industrial processes require public consultation on regulations, land use, funding, environmental impacts and more. This all slows down their adoption.

We should embrace this reality and focus on innovations that are compatible with a zero-emissions future. Video-conferencing software cuts the need for travel but is undeveloped. Average car weight has risen steadily since 1990 and could be halved. Scrap steel is collected with little sorting and recycled into low-grade products, but it could be upcycled in renewable powered furnaces.

Bold announcements of “net-zero” targets by sunset industries such as fossil-fuel aviation cause confusion and delay the policies required to phase them out. They also distract us from innovations that can be implemented rapidly and buy us the time we need to develop real zero-emissions options.

Letters in response to this article:

Carbon taxes need to be wider and deeper / From Brian N C Sweeney, London, UK

Perhaps what we really need is negative growth / From Michael Hobbs, London, UK

Air travel could again be preserve of the wealthy / From Bernd Ewald, Oslo, Norway

We can still fly and reduce net emissions to zero / From Neil Robinson, Manchester Airport, UK

‘End to aviation’ outlook is far too pessimistic / From Bob Ward, London School of Economics, UK

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