Heathrow Airport should only be allowed to expand if airlines pay to remove carbon dioxide from the atmosphere, government climate advisers have said.
Building a third runway and new terminals, as some in the government want, would disrupt the UK’s carbon budget and make it impossible to achieve net zero by 2050 under current policies, according to the Committee on Climate Change.
The “only way” to deal with such expansion within the UK’s climate commitments was for the aviation industry to become more efficient, use an increasing proportion of “sustainable aviation fuel” (SAF) instead of fossil fuels, and pay to continually remove and store carbon from the atmosphere.
Nigel Topping, chairman of the CCC, said: “The Government cannot expand Heathrow without requiring the aviation industry to clean up its emissions. The Government must therefore legislate to require the aviation industry to fully address all emissions by 2050, either directly or through the purchase of removal engineering solutions. The ‘polluter pays’ principle must apply.”
In a report to the government on Wednesday, the CCC found that the costs of SAF and carbon removal were likely to be passed on to passengers by airlines, adding around £150 to the price of a return flight to Alicante by 2050, or around £400 to the price of a flight to New York. These costs will be introduced gradually over 25 years.
But campaigners rejected the CCC’s plan to rely on nascent technology to roll back the impact of an expansion that would commit the UK to much higher emissions for decades, and called on ministers to stop any airport expansion.
Tony Bosworth, a Friends of the Earth campaigner, accused the CCC of “holding back the punches”, pointing to a recent Tyndall Center study that found SAF and carbon removal were unproven and unlikely to increase over time to the extent needed to justify airport expansion.
“The CCC should have made it clear: there is no realistic way to expand Heathrow without disrupting the UK’s climate targets,” he said.
Frequent flights are overwhelmingly aimed at the wealthy. In any given year, only about half of people in England fly abroad, with around 80% of all flights abroad taken by people who have flown two or more flights – around a quarter of the population. Frequent flyers—those who took five or more return flights abroad in 2024—made up only 5% of the population but accounted for a third of all flights.
According to the National Travel Survey for England 2024, those in the highest income group took 38% of all flights abroad – four times more than those in the lowest income group.
The CCC said policies aimed at forcing airlines to take responsibility for cleaning up their emissions should take these inequalities into account, but stopped short of recommending a frequent flyer levy.
Rising demand for air travel in the wake of the Covid pandemic threatens to increase carbon emissions around the world. A separate study by the Transport&Environment group found that the planned expansion of Europe’s 20 largest airports, including Heathrow, would breach EU and national carbon emissions limits, even if the planes using them were more efficient and partly powered by cleaner aviation fuel.
James Richardson, CCC’s director of analysis, said the last three decades of growth in the aviation industry and the likely increase in future demand meant it was “too big” to rely on other industries to cut emissions, allowing flying to take up more space in the UK’s carbon budget. Aviation now produces more carbon than UK electricity generation, and passenger demand has almost tripled from 100 million passengers in 1990 to 300 million in 2025. It currently accounts for 9% of UK emissions and will be one of the two highest emitting sectors by 2050, along with agriculture.
A Heathrow spokesman said: “Heathrow expansion cannot be a choice between economic growth and net zero – it must deliver both. The CCC assessment does not change this and recognizes that key solutions exist today. We will continue to work with government and aviation sector partners to build on today’s proven technologies, while exploring options for how the billions of pounds passengers already pay in carbon taxes can be used to support this.”
But Tim Alderslade, chief executive of industry body Airlines UK, said the CCC’s approach was unaffordable and would “put holidays out of reach for millions, turning the clock back to a time when flying was the preserve of the rich.” He said: “You can’t solve the climate crisis by taking Britain out of the skies. The answer is affordable SAF – already cutting emissions since the mandate came into force – airspace reform by 2035 for more direct routes and increased carbon removal.”
The government is not required to follow the recommendations of the CCC, which was created under the Climate Change Act 2008 to produce five-year carbon budgets. Topping said that if Heathrow were given consent without legislation requiring the industry to clean up its emissions, “a big red light will come on in the CCC’s report to Parliament”.
Responding to the CCC’s findings, a UK Department for Transport spokesman said: “Any proposal to expand [for Heathrow] will need to be aligned with our net zero targets. We are investing £219 million in sustainable aviation fuel production and a further £43 million in cleaner technologies to support greener aviation, and the expansion could deliver around £40 billion to the economy and support up to 60,000 local jobs.”