Gatwick expansion tests UK climate goals as aviation emissions rise

The plan for a second Gatwick runway could translate into about 100,000 additional flights each year, a development that puts renewed focus on how the United Kingdom will meet its climate targets as aviation grows. Government and industry surveys point to a broader pattern: if Heathrow secures permission for a third runway and an expansion of Luton airport proceeds, total additional flights could amount to several hundred thousand annually, intensifying pressure on emissions reduction efforts while the country seeks to keep its net-zero commitments on track.

Expanding airport capacity at Gatwick would intensify demand for flights, most notably in the international leisure sector that has driven recent growth. Meeting the net-zero by 2050 target would require substantial cuts in aircraft emissions even as the aviation system expands. Some steps can yield immediate gains, such as replacing older jets with newer, more efficient models. For example, a current-generation Airbus A320neo is about 15% to 20% more fuel efficient than its predecessor, helping to reduce fuel burn and, in turn, emissions. Yet improvements in efficiency alone will not be enough to offset higher demand if growth outpaces decarbonisation measures.

The United Kingdom Climate Change Committee (UKCCC) has warned that emissions from flying pose a risk to the country’s climate targets. The committee noted that last year, emissions from aviation rose by around 9%, a rise attributed to growing demand for international leisure travel. The UK’s legally binding carbon budgets include aviation and shipping as part of the effort to keep warming well below 1.5 degrees Celsius, and decisions about expanding airports could have a meaningful impact on whether those budgets are met. In 2021, the government agreed that its carbon budgets for 2033 onward would incorporate the UK’s share of international aviation and shipping, tying airport policy directly to climate outcomes for decades to come.

A central pillar of the government’s plan to reconcile growth with decarbonisation is the development of sustainable aviation fuels (SAF). SAFs are produced from waste oils, biomass feedstocks such as wood or agricultural residues, or synthesized from captured carbon dioxide and water. When burned, SAFs can deliver considerably lower net emissions than conventional jet fuel, but the actual environmental benefit depends on the feedstocks and production methods used. Moreover, current SAF supply is limited and prices are high, which has prompted the government to pursue a broader market for sustainable fuels.

A SAF mandate currently requires that 2% of all jet fuel supplied in the UK this year be considered sustainable, rising to 10% by 2030 and 22% by 2040. A bill before Parliament would establish a revenue certainty mechanism to guarantee a minimum price for SAF producers, a policy intended to encourage investment in production capacity. In practice, the mechanism would be paid for by a levy on fuel suppliers, a cost that could be passed along to passengers in higher ticket prices. The policy mix aims to attract more SAF production and bring down costs, though it remains to be seen how quickly supply can scale up to meet demand as airport capacity expands.

Beyond SAF, the outlook for longer-term decarbonisation includes radical technologies. Some plans envision hydrogen-powered aircraft, but such designs would require a wholesale shift in aircraft architecture and airport infrastructure, plus a reliable supply of affordable green hydrogen produced from renewable energy. While electric or hybrid planes might offer environmental benefits, current battery technology constrains their use for long-haul routes, limiting near-term applicability. Policymakers say that achieving meaningful emissions reductions from aviation will require a mix of strategies, including operational efficiency, SAF uptake, sector-specific mandates, and advances in propulsion and storage technologies.

All of these pieces come together as the government and industry weigh airport expansion against climate obligations. Decisions about Gatwick’s second runway—and any accompanying capacity increases at Heathrow or Luton—will be assessed not only on transport and economic grounds, but also on their alignment with carbon budgets, sustainable fuel policy, and the pace of decarbonisation in aviation. As the UK pursues net-zero by 2050, the industry faces the challenge of delivering more flights while dramatically reducing the climate footprint of air travel, a balancing act that will shape policy and travel for years to come.