Last reviewed 13 November 2023

The UK is steadily decarbonising its economy and decoupling emissions from economic growth. Official data shows that, from 1990 to 2021, emissions fell by 48% while the economy grew by 65%. However, against this upbeat background, Britain faces a long journey to meet its net zero emission commitments in a year and in the month of November, when 198 nations will meet at the UN COP28 climate summit in the UAE to close the gap between carbon-cutting promises and delivery. While there is mounting pressure on millions of companies, organisations, private citizens and particularly drivers to reduce their carbon footprints, aviation decarbonisation is a rising priority for a sustainable future in which the benefits of air travel remain available, Jon Herbert reports.

No flights of fancy

Transport is the UK’s largest greenhouse gas (GHG) emitting sector, and, on its current flight path, aviation may still be a major contributor by 2035. Reducing aviation’s high carbon profile is central to the UK’s Jet Zero Strategy, which has reported considerable progress since its launch in 2022.

The strategy faces a stiff climb. In just 27 years, the aviation sector must make radical low-carbon cuts that might seem at odds with the continuing thunder of jet engines at airports.

The challenge is to maximise the use of new airframe designs, cut out wasteful air routes and bring on innovations like sustainable air fuel (SAF) — defined as renewable or waste-derived aviation fuels that meet sustainability criteria — while keeping flight open to businesses, freight and the public.

SAF used in reduced-carbon blends is hampered by high costs and material shortages. However, better air traffic management, plus new aircraft with lower weights, advances in propulsion technology and different aerodynamics bringing gains, in addition to simple fuel efficiency, are all now priorities.

Binding international agreements to cut aviation emissions and the potential future use of hydrogen made with green electricity instead of fossil fuels are also ingredients in the low-carbon mix.

Carbon figures

The Department for Energy Security and Net Zero’s data shows that aviation activity and emissions which fell below 2019 levels in the pandemic are steadily increasing again, making urgent decarbonisation vital.

In 2021, UK aviation emissions were 14.0 MtCO2e (13.3 MtCO2e from international travel and 0.7 MtCO2e from domestic aviation) — this was some 63% below 2019 peak levels. There was a further 9% reduction on 2020 emissions.

Provisional 2022 estimates for UK international flight show that as the sector activity recovered, emissions increased to 26.0 MtCO2e — a 95% increase on 2021, but still 29% below 2019 levels.

SAF pros and cons

SAF produced from sustainable feedstocks has a chemistry similar to traditional fossil jet fuels. Feedstocks can include cooking and other waste oils, solid waste from packaging, paper, textiles, food, forestry, wood and energy crops.

Jet fuel delivers a lot of energy for its weight. However, a return London to San Francisco flight could also create a circa one tonne CO2e carbon footprint per standard ticket. Cutting this back is essential.

SAF can cut carbon emissions by up to 80% compared to traditional fuel, depending on feedstock, production and supply chains. It can also be blended in up to a 50% mix with traditional jet fuel and handled similarly. Aircraft certified to use current specification jet fuel can use SAF. 

The drawback is that SAF is currently more costly than traditional fuel due to shortages of sustainable feedstock and the cost of development of new production technologies. As technologies mature, prices are likely to fall, making them more accessible for flight operators and passengers.

Recent progress

The irony is perhaps that the 2023 Paris Air Show at Paris Le Bourget airport happened at the same location as the milestone COP21 climate summit in 2015, where the net zero Paris Agreement was struck. Nevertheless, the aviation sector points to substantial progress on its long-haul journey.

The Government’s July 2022 policy paper Jet Zero Strategy: Delivering Net Zero Aviation by 2050 drew on over 1500 consultation responses.

Jet Zero Strategy: One Year On details a series of successes reaching through into 2023 based on three guiding principles and six core policy measures, and describes future steps and challenges.

The Jet Zero Council: Delivery Group 2-year Plan meanwhile focuses on SAF and zero-emissions flight (ZEF).


The Government is said to be committed to the Jet Zero Strategy but flexible about its delivery.

The Jet Zero Strategy is based on the following three principles.

  • Strong international leadership.

  • Good delivery partnerships.

  • Maximised opportunities.

It has the following six core policies.

  • Greater system efficiencies.

  • SAF.

  • ZEF.

  • Carbon markets and carbon removals.

  • Influencing future consumer behaviour.

  • Non-CO2 issues.

The Department for Transport says considerable progress has been made since the publication of the Jet Zero Strategy, including:

  • UK leadership helping to secure a new net zero by 2050 goal for international aviation that sends an important policy signal to the global market

  • publishing a second consultation to mandate SAF use, and delivering another round of the Advanced Fuels Fund, both positioning the UK as a SAF development, production and use leader

  • Publishing the Government’s Developing the UK Emissions Trading Scheme consultation response with commitments for aviation, which include a net zero consistent cap and the phasing-out by 2026 of aviation-free GHG allocations.

To stress the importance of international leadership in a highly interconnected global sector, the UK has also played a key role in influencing the adoption by the International Civil Aviation Organization (ICAO) of a new global goal for international aviation to reach net zero CO2 emissions by 2050.

The Government has also been working towards the Third ICAO Conference on Aviation and Alternative Fuels (CAAF/3) in November 2023, where the goal has been to agree on a SAF global target and framework.

Further successes

Work to improve airspace, aircraft and airports system efficiencies includes support for the 2040 Zero Emission English Airports Target, co-developing ultra-efficient emission technology via the Aerospace Technology Institute (ATI) Programme, and £9 million for the Airspace Modernisation programme.

Supporting SAF

Key successes here have included launching the £165 million Advanced Fuels Fund (AFF), supporting commercial-scale SAF developments in the UK, and publishing experienced independent assessor Phillip New’s report on Developing a UK Sustainable Aviation Fuel Industry.

Supporting ZEF

Significant decarbonisation potential in ZEF has led to a co-invest in new zero-carbon emission technology via the ATI Programme, and airport preparedness to manage hydrogen aircraft through a £4.2 million for the Zero Emission Flight Infrastructure (ZEFI) programme.

Carbon markets and removals

These are seen as essential Jet Zero levers. Recent developments include talks to uphold the environmental integrity of ICAO’s Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA).

Influencing consumer behaviour

This is another important strand. The aim is to allow people to continue flying as they need or prefer, while helping them to make sustainable choices. A priority is to provide the environmental information they need to search for or book flights.

Non-CO2 gases

Non-CO2 gases also affect the climate. Research is helping to determine the impacts of nitrous oxides (NOx), sulphur dioxide (SO2), water (H2O) and particulate matter (soot), as well as identify mitigation options. A Non-CO2 Task and Finish Group recently reported as part of the Jet Zero Council.