'Groundbreaking Result for Climate Justice': UK Appeal Court Rules Plans for Third Runway at Heathrow Airport Illegal

Climate campaigners celebrated an "amazing and historic win" Thursday after a United Kingdom court ruled against plans to build a third runway at London's Heathrow Airport because the government's approval of the expansion "had not taken into account its own firm policy commitments on climate change under the Paris agreement."

The Court of Appeal, which is second only to the U.K.'s Supreme Court in England and Wales, called the government's failure to consider its climate obligations "legally fatal" and said that "the court will not permit unlawful action by a public body to stand." Heathrow is Europe's busiest airport and its two runways are currently at full capacity.

Although the court's ruling means the third runway could still technically be built in the future, advocacy groups opposed to the airport's expansion welcomed the Thursday's decision as a victory. As Friends of the Earth put it: "This ruling is an historic and groundbreaking result for climate justice and for future generations."

Putting the legal win into a global context, Friends of the Earth tweeted that the court's decision is "a victory for all those facing flooding in the U.K. right now, for those who've had to flee fires in Australia, for the people around the world on the front line of this #ClimateCrisis."

U.K. Transport Secretary Grant Shapps responded to the ruling on Twitter, saying that "airport expansion is core to boosting global connectivity. We also take seriously our commitment to the environment. This [government] won't appeal today's judgement given our manifesto makes clear any #Heathrow expansion will be industry led."

Heathrow Airport--which is owned by Ferrovial, Qatar Investment Authority, and China Investment Corp--said Thursday that "we will appeal to the Supreme Court on this one issue and are confident that we will be successful. In the meantime, we are ready to work with the government to fix the issue that the court has raised."

Tim Crosland, director of the British legal charity Plan B, which brought the legal challenge, welcomed the court's decision and the government's acceptance of it.

"It would have been hard to imagine this outcome even a couple of years ago, but as the scale and impacts of the ecological crisis become clearer, with people dying and being displaced in the U.K. and around the world, it's vital we reject the politics of division and unite in adversity," Crosland said in a statement (pdf).

"This is an important moment for all of us, and for our young people in particular. Some sanity is finally prevailing," he added. "It's all those people who have been working so hard to sound the alarm, whether by taking to the streets or in other ways, who have made this outcome possible. The message is finally getting through. The bell is tolling on the carbon economy loud and clear."

Plan B along with fellow climate campaigners and experts suggested that the ruling could have far-reaching consequences in terms of forcing governments worldwide to honor their climate commitments. Margaretha Wewerinke-Singh, an international public law expert at the Netherlands' Leiden University, told the the Guardian that "its implications are global."

"For the first time, a court has confirmed that the Paris agreement temperature goal has binding effect," said Wewerinke-Singh. "This goal was based on overwhelming evidence about the catastrophic risk of exceeding 1.5degC of warming. Yet some have argued that the goal is aspirational only, leaving governments free to ignore it in practice."

Advocacy groups from across the globe took to Twitter Thursday to express excitement over the court's ruling:

Climate activists in the U.K. and beyond also celebrated the news on social media:

British politicians at various levels of government also welcomed the court's decision:

"Today's landmark judgement against a third runway at Heathrow is the most important environmental case for a generation, but we will not stop here," London Mayor Sadiq Khan vowed Thursday. "The fight for a greener, cleaner London continues."