The expansion of Heathrow airport has been ruled unlawful by the Court of Appeal in a victory for climate campaigners fighting to block controversial plans for a third runway.

Judges ruled the government's decision to permit the expansion of the UK's busiest airport was illegal because ministers did not take into account the impact on the country's commitment to tackle global warming.

Heathrow is expected to challenge Thursday's ruling, but the government has not lodged an appeal and campaigners said they hoped Boris Johnson would abandon the project.

Legal action had been brought by a group of councils in London affected by the expansion, environmental charities including Greenpeace, Friends Of The Earth and Plan B, and London mayor Sadiq Khan.

Lords Justice Lindblom, Singh and Haddon-Cave ruled the government did not take enough account of its commitment to the Paris Agreement on climate change when setting out its support for the proposals in its National Policy Statement (NPS).

The UN's Paris Agreement, which came into force in November 2016, commits signatories to take measures to limit global warming to well below 2C.

Lord Justice Lindblom told the court: "The Paris Agreement ought to have been taken into account by the Secretary of State in the preparation of the NPS and an explanation given as to how it was taken into account, but it was not."

Cait Hewitt, deputy director of Aviation Environment Federation, said: "This is a huge win for the climate, and leaves Heathrow’s third runway plans in tatters. In presenting plans for a third runway to MPs, the Government failed, the court has found, to assess whether this was compatible with the Paris Agreement. 

"The project would increase emissions at the UK’s biggest airport, and the UK has since legislated to achieve net zero emissions by 2050, so it’s very hard to see how the Government could now ever demonstrate that a third runway could be reconciled with the necessary scale of climate action.

"This ruling should mark the end of plans for any new runways in the UK. The Government should stand up to the airports lobby, drop its support for airport expansion, and invest instead in low-carbon transport and supporting British tourism."  

Will Rundle, head of legal at Friends of the Earth, added: “This ruling is an absolutely ground-breaking result for climate justice. We were fighting a project that would have had dire implications for present and future generations.”

Mayor of London Sadiq Khan said the court ruling was "huge".

He added:  I’m delighted that the Court of Appeal has recognised that the government cannot ignore its climate change responsibilities. I will continue to stand up for Londoners’ concerns by doing everything I can to stop the Heathrow expansion."

But the results of the ruling will have come as a blow to the UK airline industry.

Tim Alderslade, chief executive of Airlines UK, the industry body representing UK-registered airlines, said: "Today’s decision is extremely disappointing. The Sir Howard Davies Airports Commission spent several years looking at airport capacity in the South East and was clear Heathrow is the only game in town, with other schemes being considered and ultimately rejected.

"The economic prize is enormous if expansion is done right, with airlines ready to respond to the unlocking of new capacity by creating new routes and helping to connect the UK to new markets and destinations, and Heathrow to regions across the country. UK aviation has committed to net zero carbon by 2050 and this factors in the emissions created by Heathrow expansion. It is not a question of being pro-aviation or pro-environment."

The results of the ruling were announced this morning following a hearing in October last year.

Read More