A report from the University of Manchester's Tyndall Centre for Climate Change Research, commissioned by Friends of the Earth, concludes that allowing a third runway at Heathrow would cause the UK to overshoot its legally binding climate targets. The analysis comes as the Government's consultation on the Heathrow expansion national policy statement (HENPS) closed on Tuesday, with opponents urging rejection.
Aviation already exceeds carbon budget
The Tyndall Centre's new modelling shows that the UK aviation industry is already forecast to exceed limits set in the seventh carbon budget, part of the national plan to reach net zero by 2050. This projection exists before a third runway is built and follows recent approved expansions at Gatwick, Stansted, and Luton airports.
The report also states that, based on existing evidence, sustainable aviation fuels, such as used cooking oil, would not be able to close the gap between carbon emissions and targets. Research fellow Lois Pennington from the Tyndall Centre said: "Every aviation scenario the UK Government has published overshoots the carbon budget Parliament has legislated, before a third runway at Heathrow is even taken into account."
Opponents decry expansion amid record heat
Friends of the Earth's head of policy, science and research, Mike Childs, described the expansion plans as "the climate equivalent of pouring petrol on a raging wildfire" after summer 2026 was provisionally confirmed as the hottest on record in the UK, with widespread drought and wildfires. He noted nearly 3,000 excess deaths during the summer.
Childs said: "The evidence is clear: there is no route where expansion at Heathrow can be in line with our legally binding climate targets. The Government has a choice: commit to taking action on the climate seriously, reject Heathrow expansion and constrain excessive flying, or abandon the UK's climate targets and future generations by giving the third runway the go-ahead."
Heathrow argues for growth
After Istanbul surpassed Heathrow as Europe's busiest airport in July, the west London airport argued that "the case for expansion has never been clearer." The airport said it was "operating at capacity" and that its expansion plans "will ensure the country gets the infrastructure it needs to stay competitive and will deliver all-important economic growth."
The scheme, estimated to cost £33 billion, including £1.5 billion to move the M25, is expected to be fully privately financed. It would increase Heathrow's capacity to 756,000 flights and 150 million passengers per year.
Government response and next steps
When the consultation was launched in June, Transport Secretary Heidi Alexander said: "The Government considers that the development covered by the Heathrow expansion NPS is critical to national growth and therefore plans to designate expansion at Heathrow as critical national growth infrastructure."
Mayor of London Lord Sadiq Khan said he was "deeply concerned" about potential adverse impacts, citing air quality, noise pollution, the environment, and other transport networks. He added: "The truth is the whole case for Heathrow expansion relies on outdated evidence that fails to consider the urgent challenges we face today. I will continue to vehemently oppose these plans as I seek to build a fairer, safer, greener, more prosperous London for everyone."
A Department for Transport spokesperson said: "We are grateful to everyone who took the time to engage with the HENPS consultation and have received responses from a wide range of stakeholders. We will now carefully consider all responses before setting out next steps later this year. We have always been clear that expansion will only go ahead if it is delivered in line with our legally binding climate change obligations, and meets strict environmental rules on air quality and noise pollution."
