This post is by Alethea Warrington, campaigns manager at climate action charity Possible.
Although the government’s recognition of the need to tackle aviation emissions is welcome, its scenarios to achieve net zero aviation by 2050 are fatally flawed. It relies on undeveloped, extremely expensive or unworkable technologies, and refuses to implement an essential part of the solution: policies to fairly reduce the demand for flights.
The recent transport decarbonisation plan and ‘Jet Zero’ consultation set out a bright new world of decarbonised flight: new types of aircraft powered by hydrogen, electricity or alternative fuels, improved efficiency and remaining emissions removed. With this, the government hopes to avoid having to implement policies that actually discourage people from flying. But its projections for what can be achieved without reducing demand are hopelessly over optimistic, relying on breakthroughs to overcome hard technical or physical barriers.
The reliance on technological breakthroughs is worrying
The Department for Transport (DfT) expects efficiency improvements to provide more than a third of aviation’s 2050 emissions reductions. The annual improvements they expect are higher than even the industry’s own forecasts, and the DfT ignores the fall in the rate of improvement over time. The plan also fails to acknowledge that improved efficiency has actually increased emissions, as lower fuel requirements have reduced costs and increased demand. The Jet Zero plan proposes nothing to overcome this.
Despite the department’s enthusiasm for the zero emissions aircraft, which don’t exist yet, it is more realistic about their potential to decarbonise flight by 2050. Without a breakthrough on new types of aircraft powered by hydrogen (which would still produce greenhouse gases) or electricity, they are expected to contribute just four per cent of emissions reductions by 2050 and, even with innovations in how they are powered, their contribution is expected to be less than 13 per cent. This reflects the well known problems in developing alternative types of aircraft. The additional weight of battery storage and volume of hydrogen make it very difficult to power planes capable of anything beyond short distances and small numbers of passengers.
On sustainable aviation fuels (SAFs) the department is again hoping for a breakthrough which, in theory, would allow abatement of more than a third of aviation emissions. Without this though h, even under a high ambition scenario, the contribution of SAFs to emissions reductions by 2050 is only around 14 per cent. However, this is based on some highly questionable assumptions, including that alternative fuels can provide a 100 per cent reduction in carbon emissions. The only type of alternative fuel which is genuinely low carbon (although not zero emission) is efuel, which uses renewable energy to capture carbon from the air and combine it with green hydrogen. Unsurprisingly, this is an expensive, high energy process, which is currently only at proof of concept stage.
Even assuming that the best case breakthrough scenarios the government hopes for do, in fact, emerge, this still would not achieve the full sectoral emissions reduction required to meet net zero by 2050. So, what’s the plan?
Aviation offsets just don’t work
The government expects other sectors to deal with the problem, while planes keep on polluting or, as the DfT puts it, “abatement outside aviation sector” is used. The DfT’s implied equivalence between offsets, or market-based measures, and actual carbon removals via negative emissions is worrying. Aviation offsets have been shown to be deeply flawed. Nor should the government hope to rely on negative emissions projects to remove the millions of tonnes of aviation emissions which remain in their scenarios, as these are highly speculative. These projects would, in any case, still not address the two thirds of aviation’s contribution to global warming which comes from the non-CO2 greenhouse gases the sector emits.
On industry targets, the net zero proposals for 2040 for domestic aviation and airport operations mean little. Much greater emissions reductions could be achieved by prioritising train travel for domestic journeys, electrifying the rail network and ensuring trains are affordable. Reductions to the around one per cent of airport emissions which come from airport operations, rather than the aircraft themselves, are no more than greenwash while airports attempt to force through their plans to expand, regardless of the climate crisis.
Discouraging frequent flying is popular
Yet the government refuses to include the one measure we know would work and could be introduced now: fair demand reduction. With just 15 per cent of people in the UK taking 70 per cent of the flights, and half of people not flying at all each year, there’s huge potential to cut aviation emissions by discouraging frequent flying, without affecting the majority of people who fly once or less each year. Recent polling by the Department for Business, Energy and Industrial Strategy found that a majority of people in the UK are in favour of a frequent flyer levy, a progressive tax which increases with every flight a person takes in a year, with fewer than one in five people opposed.
While the government hopes that technofixes will decarbonise aviation, there is no sign of policies to encourage this, such as a sufficiently high emissions tax to narrow the cost gap between kerosene and efuels, or a tax on jet fuel. Although the DfT refuses to bring in progressive policies to reduce demand and make flying fairer, it does acknowledge that the costs of new technologies and fuels are likely to reduce demand (unless the costs are covered via taxes, which would be regressive). Without a progressive tax, relying on increasing aviation costs alone to manage demand will result in the situation the frequent flyer levy aims to prevent: that the wealthiest continue flying often in a carbon-constrained world, while ordinary travellers who rarely fly are priced out of the skies.