From Extinction Rebellion to the youth climate strikers and Greta Thunberg’s visit to the UK, climate change is finally making its mark on our political and public consciousness.

When David Attenborough – the country’s most valued national treasure – warns “the collapse of our civilisations and the extinction of much of the natural world is on the horizon”, people sit up and listen. And not a day too soon.

The world is warming at an alarming rate. Wildfires, droughts, heatwaves, and floods are becoming more common. Ecological breakdown is not some distant problem – the climate emergency is now our ever-present and collective challenge.

That is the reality we must confront – together. We must do it across political divides and in line with what the science demands, not constrained by what some would assert is currently “politically possible”.

The Intergovernmental Panel on Climate Change’s message is uncompromising: halve global emissions in the next 11 years and hit net zero by the middle of the century.

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Declaring a climate emergency is the first step, major investment in energy efficiency and renewables the next. I therefore warmly welcome the work that’s being done by councillors across the country to get local authorities focussed on this challenge, and welcome, too, Labour’s motion in parliament this week to declare a national climate emergency, echoing my motion from last month.

But with the clock ticking we must be honest about the need to go much further, about a bold vision that puts an end to the “growth at all costs” economic model.

The global economy is set to nearly triple in size by 2050 – that’s three times more production and consumption taking place each year. It would be difficult enough to decarbonise the existing global economy in such a short timeframe. It’s virtually impossible to do it three times over unless we are prepared to rapidly transform our entire economy.

Redesigning the economy in this way means demonstrating how environmental, social and economic justice are interconnected. And cross-party cooperation to do that is essential.

That’s why I am working with Labour MPs Clive Lewis and Ed Miliband on big ideas like a Green New Deal. There are not many win-wins in politics, but a green industrial revolution – a massive job creation programme – is one of them. With it comes good quality jobs that can’t be offshored; retrofitting all of the 30 million buildings in Britain and installing green energy wherever possible; making a significant reduction in climate emissions; and bringing about an end to fuel poverty.

Agriculture must play its part too – we need a rapid transition away from industrialised farming and towards a more plant-based diet.

But whilst some on the opposition benches grasp the severity of this situation, there are exceptions. MPs might be falling over themselves to get selfies with Thunberg, but their policies still don’t stack up.

We know it’s not possible to tackle climate change and expand airports or build new runways. Heathrow, already produces as many greenhouse gas emissions as Croatia. A third runway would result in a further 300 million tons of CO2 being belched into the atmosphere annually.

We cannot tackle the climate crisis whilst investing in new roads. A third of current UK emissions come from the transport sector. There are alternatives to fossil fuel cars, but we must invest in them and set a far more ambitious phase-out date for old and dirty technology.

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We cannot tackle climate change whilst at the same time backing new fossil fuel extraction. Britain’s first new deep coal mine in 30 years has been given the go-ahead by Cumbria County Council – backed by Labour, Liberal Democrat and Conservative councillors. This decision is a slap in the face for the young people striking for a future. And yesterday shadow communities secretary Andrew Gwynne went one further on the Andrew Marr Show by suggesting that digging new mines was somehow justifiable.

And we cannot tackle climate change while wedded to an economy that assumes the Earth will somehow magically meet our ever-expanding use of resources.

This is a unique moment in history and the decisions we make right now matter. So yes, let’s unite across the political divides to declare a climate emergency. And let’s also be honest – responding to this crisis cannot be done by maintaining the status quo. Every political party must face the truth or gamble with the fate of humanity.