This article originally appeared on VICE UK.

Yesterday, just hours before MPs voted to declare a climate emergency – making the UK the first country to officially do so – news broke from the High Court: campaigners had lost their attempt to stop the expansion of Heathrow Airport with a third runway.

Five separate appeals were made to legally challenge the proposals, by various organisations and individuals, from Greenpeace to the Borough of Hillingdon to a man called Neil. The grounds varied, from protecting habitats, to air quality, to competition rules, but the central argument came down to the threat of climate change: campaigners argued that the government was acting illegally by not taking into account the Paris Agreement (which seeks to keep a global temperature rise below 2 degrees) when giving a third runway the green-light. The judges didn't buy it.

Heathrow's expansion is symbolic of everything that's been so wrong about the UK's approach to climate change. The great and the good nod their heads and say the right things; meanwhile, it's full steam ahead with adding another 260,000 flights a year to Heathrow's current 480,000 capacity. The airport is already the UK's biggest polluter, and it's set to get much worse.

Only eight Tory MPs voted no to Heathrow expansion. Meanwhile, Jeremy Corbyn – who yesterday led the charge to declare a climate emergency – let his benches have a free vote on the issue. He voted against, but 119 Labour MPs supported the expansion last year. In line with the declaration of a climate emergency? Obviously not.

It goes without saying that the Tories have been useless on climate change: they banned onshore wind projects; scrapped warm homes standards; shafted solar energy; sold off the Green Investment Bank; fracked all over the place and refused to meet the climate strikers this year. Under Corbyn, Labour have made the right noises, but it's only really in the last month or two – with groups like Extinction Rebellion forcing the issue onto the agenda – that talk of climate emergencies, Green New Deals and Green Industrial Revolutions have really come to the fore.

So, yesterday's declaration raises two questions: what does declaring a climate emergency mean in practice? And how serious is Labour about the environment?

Sue Hayman.

"Declaring a climate emergency does two things," explains Sue Hayman, Labour MP for Workington and Shadow Environment Secretary. "It shows we are listening to and taking seriously the evidence that scientists are giving us. We also know there has to be action, and this motion will kickstart it."

We're in a meeting room in the Houses of Parliament. Next door, Jeremy Corbyn is meeting with the Icelandic Prime Minister; in the chamber, MPs are discussing the climate emergency motion, which came from Hayman's team. The way she sees it, the declaration doesn't just make it clear climate change is a problem, it demands that government increases the ambition of the UK's climate change targets, and calls on them to bring to Parliament – within the next six months – a "series of urgent measures to restore nature and move towards a circular, zero waste economy".

I’d asked the same question to Caroline Lucas, the UK's only Green MP, just a few hours earlier. "What it means is that it changes the parameters of what's politically possible," she said. "Right now, there's a fight between what is politically possible and what's scientifically necessary." In particular, she pointed to the mobilisation of resources: "When we had the financial collapse, hundreds of billions of pounds were found to bail out the banks in a way one couldn't have imagined before that crisis. In a moment of crisis things become possible: there'll be a mobilisation of resources and political will in a way rarely seen outside of periods of conflicts and war."

It all sounds fairly promising, until you remember that both Labour and the Greens have accepted the fact that climate change is a problem for decades. "Sadly, declaring a climate emergency doesn't in and of itself put in place a set of laws to screen out climate vandalising policies in the future. I wish it did," sighed Lucas, "but it doesn't."

Sue Hayman.

Back in Parliament, Sue Hayman is discussing Labour's record. "The Labour Party supported renewable energy when it was in government," she says. "We introduced the Climate Change Act (2008), which was groundbreaking at the time. Since then, unfortunately the Tories and coalition before it have reversed our direction of travel."

The noises Labour are making now are positive: there's talk of a Green New Deal, and they've published a plan for a Green Industrial Revolution and a Clean Air Act. "We’re also devising something right now called Labour's Plan For Nature," says Hayman, "and then there’s the investment in public transport, education and environmentally sustainable housing – I’m working to make sure it’s top of the agenda across every department."

As she talks me through a number of other plans and proposals, I wonder whether Labour are just jumping on the climate change bandwagon because groups like Extinction Rebellion have made it popular; it hasn't seemed to be of much concern until now.

"It certainly helps to have young people and activists talking about what they consider to be important, because then government and all parties start to listen," says Hayman when I ask. "We've always talked about the environment, and I tried to push it up the agenda. Brexit has just totally dominated everything – you have to shout even more loudly to get heard." In fact, she says, her team have been working closely with John McDonnell, the Shadow Chancellor, and Clive Lewis MP: "It may not have been shouted about in public, but there’s been an enormous amount of work going on behind the scenes."

"What’s frustrating is people often complain to me that [Labour] aren't talking about the environment, and I say that I do, but nobody picks it up," she adds.

Protesters in Parliament Square.

It's also worth bearing in mind that, for Corbyn and McDonnell, the accusation that they’re only acting due to public pressure on climate change is one they'd take pride in, whether or not it's actually the case.

"Protesters and school-strikers told us to act. Governments never act without pressure, and we must keep the pressure up," said Corbyn after the vote yesterday.

When I first sat down with the pair for VICE in April of 2015 – when they were barely relevant backbenchers – the two made it clear that, should they ever take control of the party, social movements and activists would need to hold them to account. "Get involved in campaigns, in a union, with the peace movement, get involved with Occupy and UK Uncut," said Corbyn, before adding, "And also be in a political party."

After I've spoken to Hayman, Amelia Womack, Deputy Leader of the Green Party, tells me outside Parliament that she believes Labour are weaker on the environment: "The fact the Green Party took clear leadership on climate is important – where we go, others follow," she says. "It's frustrating for many of our local parties where Labour parties have watered down climate emergencies: in Liverpool, Knowsley, Exeter, Sheffield, the list goes on." There is also, of course, the huge new Cumbrian coal mine that Labour, Lib Dem and Tory councillors all backed.

Protesters in Parliament Square.

On Parliament Square, a crowd is gathering; the Commons vote is about to be held. Before she takes the stage, I ask Aliya Yule – Co-Director of Labour for Green New Deal – if she's confident that Labour will make climate change their priority for good. "I would say the recent, current focus on climate is exciting and promising," she replies.

Yule recalls hearing Rebecca Long-Bailey – Labour's Shadow Secretary of State for Business Energy and Industrial Strategy – speak in February this year. "She said that Labour needs a grassroots movement to push them to have more radical climate policies," she remembers. "There's a real desire to be much stronger on this – the last two weeks have demonstrated it." Add to that the fact that Labour compared Extinction Rebellion to the anti-apartheid movement, the list of new policies and their declaration of a climate emergency – and Yule says things are looking up.

"That said," she adds, "Labour announced the Green Industrial Revolution, but the policy hasn’t really changed, the targets are the same as they were in 2017 – although that's still better than the government’s."

Yule argues that Labour should go a lot further, and says it’s an issue activists will be pushing at Labour Conference this year. Who knows? Maybe now Labour might even take a bolder stance on Heathrow’s third runway. "Bizarre court judgment on Heathrow airport expansion that lets government off the hook because it has not put Paris Climate Change Agreement into UK law," John McDonnell tweeted following the ruling. "Campaign goes on. Appeals certain. This is just the first stage in defeating 3rd runway & protecting our environment."