Peter Campbell in London Published September 15 2026 Jump to comments section Print this page Unlock the Editor’s Digest for free Roula Khalaf, Editor of the FT, selects her favourite stories in this weekly newsletter. Expanding Heathrow would add as much carbon to the atmosphere as the city of Birmingham and is incompatible with the UK meeting its legally binding climate targets, the independent Climate Change Committee has warned.

The CCC on Wednesday said a third runway at Britain’s sole hub airport would release 4.5 megatonnes of CO₂ or equivalents a year by 2054 — equal to the current emissions output of the UK’s second city — even with the expected take-up of cleaner fuels and newer aircraft. “There is no credible pathway for Heathrow airport expansion within the UK’s climate commitments under current policies,” the committee said in a report.

Ministers — who have backed expansion at Heathrow as a means of boosting economic growth — had asked the CCC to study the project, as well as to look more broadly at the UK’s aviation landscape. The committee, which advises on climate policy, found that flying emissions would breach targets without significant changes to the government’s policy — even without Heathrow’s planned expansion. Ministers have backed the £33bn third-runway expansion at Heathrow as a means of boosting economic growth © Heathrow Even without a third runway — which is part of a £33bn plan by the airport and opposed by environmental campaigners — aviation emissions would rise from 37 megatonnes of CO₂ or equivalents a year by 2050, it found. “Heathrow just makes the problem worse,” said James Richardson, CCC chief economist.

Decarbonising aviation is significantly harder than other transport industries, with electric aircraft decades away and able to fly only short distances. There is also not enough sustainable aviation fuel to meet current targets set by the government, despite SAF already being four times more expensive than jet fuel. In addition, SAF is produced by oil companies rather than airlines, which have complained that they are being penalised for another industry’s failure. However, the committee argued that airlines should bear the cost of reducing emissions in the sector.