Net zero and the role of the aviation industry

The aviation industry contributes around 1 per cent of UK GDP and provides additional unquantifiable benefits, including aiding the expansion of business investment and enabling people to visit family members who live abroad. However, there is a significant risk that by 2030 the global carbon budget – to retain a 67 per cent chance of averting more than 1.5°C of global warming – will be exhausted. The aviation sector remains extremely difficult to decarbonize, with the deployment of supply-side solutions likely to take decades. Near-term policies to manage demand within the aviation sector could play a role in buying time for the development of supply-side decarbonization solutions, such as advanced next-generation aircraft and sustainable aviation fuels. While this approach may be politically challenging, the climate risks associated with surpassing 1.5°C – when tipping points may begin to kick in and lead to runaway climate change – make it vital to examine what level of demand management may be required, and what it may entail. The focus on demand management in the aviation sector is gaining traction. In December 2022, the European Commission gave France the green light to ban short-haul domestic flights between cities linked by train journeys of less than 2.5 hours. In the UK, the Climate Assembly has shown that the British public supports limits on flying, depending on how technological solutions progress. Demand-management policies and technological solutions can work in parallel: as supply-side technologies are commercialized and deployed, demand-management measures could be eased. In October 2022, the UK Committee on Climate Change noted in its progress update that it is considering ways of mitigating the risks of relying on supply-side solutions, ‘The Government’s plans for aviation focus on sustainable aviation fuel and zero/low-emission aircrafts. These technologies have potential, but there are significant risks in their delivery. In the near term, managing demand would have a much greater benefit for the climate.’ The model developed for this paper explores the role of demand management following analysis of the main emissions abatement mechanisms of the UK government’s Jet Zero Strategy high-ambition scenario. The model covers all UK domestic and outbound international flights. According to this analysis, a prudent risk-minimization approach would be to reduce flying in terms of frequency and distances flown, over the remainder of the 2020s. Under this lower-risk scenario, UK demand in terms of passenger-kilometres flown in 2030 would need to be 36 per cent lower than in 2019 to stay within the sector’s fair share of global carbon budgets, with demand returning to 2019 levels by 2050, once supply-side decarbonization has caught up. In the UK the top fifth of earners fly five times more often than the poorest fifth. It may be possible to achieve a 36 per cent reduction in demand by 2030 if a future demand-management policy shifted behaviour so that most people who currently take more than one return flight per year reduced that number by one return flight and took no more than four. This would leave the 77 per cent of the UK population who currently take no more than one return flight unaffected. This is a moderate level of behaviour change to put the aviation sector on a climate-compatible trajectory. The impact of non-CO₂ effects – such as water vapour emitted at high altitudes as part of an aircraft’s contrails – remains uncertain and poses a further threat to already limited carbon budgets. Even the most optimistic interpretation of this uncertainty indicates that if non-CO₂ effects were to be factored in, there would need to be significantly greater reductions in demand. If near-term action to reduce demand is delayed, but the UK aviation sector is still to stay within its fair share of global carbon budgets, demand in 2050 will need to be around one-quarter lower, relative to 2019. This scenario does not factor in non-CO₂ effects and embodies considerable additional risk. Namely, that a significant proportion of the dwindling carbon budget is used up over the next decade, leaving humanity to rely on uncertain future supply-side decarbonization and even greater demand management in the long term.