London Heathrow’s third runway blocked for violating the Paris climate change accord

London Heathrow’s plan to add a third runway faces further delays after environmental activists won an appeal over an expansion that Europe’s busiest airport says is needed to boost flights and allow it to compete with rival hubs trying to steal its traffic.

Appeal court judges on Thursday overturned a May decision that threw out lawsuits from Friends of the Earth and other groups seeking to challenge the U.K. government’s approval of the plan. Judge Keith Lindblom said that the then-Transport Secretary acted “unlawfully when failing to consider climate change.”

The $20 billion expansion at the London hub was delayed for decades because of concerns about extra aircraft noise, increased pollution, the demolition of homes and the impact on already crowded roads. The decision risks causing further delays and uncertainty to a project that was proposed in 2002.

“Today’s landmark Heathrow judgment is a victory for Londoners and future generations,” London Mayor Sadiq Khan said in a statement. “We face a climate emergency and I’m delighted that the Court of Appeal has recognized that the government cannot ignore its climate change responsibilities.”

A Heathrow spokesperson said it will appeal to the Supreme Court, and added that any issues were “eminently fixable.”

Shares of British Airways parent IAG SA, which were already falling because of the impact of the coronavirus outbreak, slumped further after the ruling. The stock was down 7.2% at 10:22 a.m.

Prime Minister Boris Johnson’s spokesman, James Slack, told reporters Wednesday that the Heathrow runway “is a private sector project” while reiterating that it must show it can meet air-quality and noise obligations “in order to proceed.”

In 2015, Johnson promised to lie down before bulldozers to stop construction of the runway, but missed the 2018 Parliament vote that that kept expansion as part of a national policy statement. Being part of that policy plan would help to minimize further procedural logjams, with planning authorities confined to considering elements of the proposal rather than whether it should be built at all.

The airport operator has spent years trying to win permission of the expansion. In 2018, it was only able to boost flight numbers 0.2% because of a shortage of slots.

On Wednesday, the airport’s chief executive officer, John Holland-Kaye, stepped his defense of the runway, saying a government decision to block the project would amount to “financial suicide” and hamper U.K. efforts to boost trade after Brexit.

Holland-Kaye said an expanded Heathrow, opposed by campaigners and some politicians because of its environmental impact, is “essential for a global Britain.” Thwarting the plan will only benefit competing economies such as France, he said in an interview.

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