London Heathrow Airport should only be allowed to expand if the aviation industry “cleans up its emissions”, according to the Climate Change Committee (CCC).
The statutory body, which advises the UK government on emissions targets, made its assessment on Wednesday (16 September) about the impact of Heathrow’s £49 billion plan to build a third runway.
“Government cannot expand Heathrow Airport without requiring the aviation industry to clean up its emissions,” said the CCC in its report. “They should legislate policies that require the industry to fully address emissions by 2050 — either directly or by purchasing engineered removals.”
The CCC added that this was the “only way” that the proposed expansion would be “consistent” with the UK’s current carbon budgets and the target of reaching net zero on aviation emissions by 2050.
The UK government has given its backing to Heathrow’s plans to expand and recently concluded a public consultation on the Heathrow Expansion National Policy Statement (HENPS), which will establish the policy framework for the project. The government wants to secure planning permission by 2029 for the project and for the runway to be operational by the mid-2030s.
In its report, the CCC said that aviation was “falling behind the rest of the economy on decarbonisation”, noting that aviation emissions have more than doubled since 1990, compared with a halving of emissions across the UK economy “as a whole” during the same period.
“Even without Heathrow expansion, under current policy, emissions would not fall at all by 2050,” warned the committee’s report.
“Heathrow expansion would make it harder to meet the UK’s climate targets. Heathrow is currently responsible for around half of aviation emissions [in the UK]. The full impact of expansion would account for 6.9 per cent of remaining carbon emissions in 2050.”
The committee compiled its report after receiving a request for advice from the Department for Transport in November 2025 about the potential impact of Heathrow expansion.
The DFT said it would “carefully consider” the CCC’s advice alongside other responses to the consultation and added that any expansion plan would “need to align with our net-zero targets”.
In response to the report, a Heathrow spokesperson said: “Heathrow expansion cannot be a choice between economic growth and net zero — it must deliver both.
“The CCC’s assessment does not change this and acknowledges that the key solutions exist today. We will continue working with government and partners across the aviation sector to ramp up today’s proven technologies, while examining options for how the billions of pounds passengers already pay in carbon taxes can be used to support this.
“Given the right policies, a growing aviation sector can be empowered to deliver the huge economic and social value that air travel brings, while increasing pace of delivery of the solutions needed to accelerate aviation’s decarbonisation.”
Tim Alderslade, CEO of Airlines UK, which represents UK-based carriers, added: “UK airlines back cost-effective airport growth and net zero by 2050 — but the transition has to be affordable. Airlines are already investing billions in new aircraft, SAF (sustainable aviation fuel) and airspace upgrades.”
Alderslade argued that the CCC’s approach would significantly increase the cost of flights from the UK in the coming decades.
“You can’t solve the climate crisis by pricing Britain out of the skies,” he said. “The answer is affordable SAF — already cutting emissions since the mandate began — airspace reform by 2035 for more direct routes, and scaled-up carbon removals.”