While Boris Johnson wants us to think of 12 December as the “Brexit election” and a battle over public spending, there is one issue whose importance dwarfs all others – climate change – and Johnson is not even showing up to talk about it.

A quick glance at the climate science makes it clear that this might be our last chance to have a “climate election” in Britain. Leading scientists from the IPCC tell us that we have until 2030 to limit climate catastrophe, and the experts say that the bulk of climate action needs to happen in the next few years to have the most impact. That means big changes – from the way we heat our homes, to how we travel and what we buy. And those changes must be led by government.

The good news is that the public supports these changes. Concerns over climate change have recently reached the highest levels for years – with 72 per cent of British adults now “very” or “fairly” concerned about the impacts of climate change. Recent polling has made it clear that British people want tough net-zero targets, with 56 per cent of the UK public – and almost half of Conservative voters – backing decarbonisation of the UK’s economy by 2030. Almost half of UK voters support “increased government spending to make local bus transport free for everyone”. And even the most radical policies – like a ban on private jets – see almost double the support compared with those who oppose them.

It’s increasingly clear to everyone that the climate emergency isn’t an abstract concept, or something that’s only affecting far away parts of the world. Look at what’s happened in the UK just this year – a searing heatwave in the summer and then widespread and destructive flooding a few weeks ago. These kind of incidents have happened before, but all the evidence points to the fact that these extreme and dangerous weather events are becoming more likely because of climate change.

When you look outside of the UK things are even bleaker. Wildfires in the US, deadly floods in Bangladesh and hurricanes hitting poor communities harder than ever. Britain led the world into the industrial revolution, and in doing so has risked condemning the world to catastrophic climate change.

Mont Blanc 100 years on: Climate change impact revealed Show all 7 1 /7 Mont Blanc 100 years on: Climate change impact revealed Mont Blanc 100 years on: Climate change impact revealed Mont Blanc aerial photographs from 1919 (left) and 2019 (right) The images show the impact that climate change has had upon the mountain's glaciers Walter Mittelholzer, ETH-Bibliothek Zürich/Dr Kieran Baxter, University of Dundee Mont Blanc 100 years on: Climate change impact revealed Walter Mittelholzer's biplane Walter Mittelholzer biplane photo ETH-Bibliothek Zürich ETH-Bibliothek Zürich Mont Blanc 100 years on: Climate change impact revealed Mont Blanc aerial photographs from 1919 (left) and 2019 (right) Mont Blanc aerial photographs from 1919 (left) and 2019 (right) showing the impact that climate change has had upon the mountain's glaciers 1919 - Walter Mittelholzer, ETH-Bibliothek Zürich 2019 - Dr Kieran Baxter, University of Dundee Permission from university to use with article Walter Mittelholzer, ETH-Bibliothek Zürich/Dr Kieran Baxter, University of Dundee Mont Blanc 100 years on: Climate change impact revealed Walter Mittelholzer Walter Mittelholzer portrait Doppelsteuer-Schulflugzeug. Herstellung K+W Thun (Lizenz Robert Wild), 1. Serie. Werk. Nr. 13 bis 18 bzw 141 bis 146, Motor Mercedes D.I. Die Ablieferung erfolgte von MÃ¤rz bis Mai 1917, im Einsatz bis 1934. (Dual control trainer aircraft. Production K + W Thun (license Robert Wild), 1st series. Plant. Nos. 13 to 18 and 141 to 146, engine Mercedes D.I. The delivery took place from March to May 1917, in use until 1934.) ETH-Bibliothek Zürich Mont Blanc 100 years on: Climate change impact revealed Mont Blanc aerial photographs from 1919 (left) and 2019 (right) Mont Blanc aerial photographs from 1919 (left) and 2019 (right) showing the impact that climate change has had upon the mountain's glaciers 1919 - Walter Mittelholzer, ETH-Bibliothek Zürich 2019 - Dr Kieran Baxter, University of Dundee Walter Mittelholzer, ETH-Bibliothek/Dr Kieran Baxter, University of Dundee Mont Blanc 100 years on: Climate change impact revealed Dr Kieran Baxter photographing Mont Blanc in 2019 Kieran Baxter in a helicopter, photographing Mont Blanc in the places where Walter Mittelholzer took images in 1919 Dr Alice Watterson, University of Dundee Dr Alice Watterson, University of Dundee Dr Alice Watterson, University of Dundee Mont Blanc 100 years on: Climate change impact revealed Dr Kieran Baxter in front of the glacier Kieran Baxter glacier portrait Dr Alice Watterson, University of Dundee Dr Alice Watterson, University of Dundee Dr Alice Watterson, University of Dundee

That historical role – the fact that a small country like ours bears so much responsibility for the carbon emissions that are now heating the world to unliveable levels – is a very strong reason for us to hold the world’s first ever televised leaders debate between party leaders. It’s no exaggeration to say that Britain must either be a world-leader in tackling the climate emergency or we will be guilty of an utter dereliction of duty.

This has been the year of the youth climate strikes, of Extinction Rebellion taking to the streets and shutting them down, of environmental campaigners putting their bodies on the line from Kenya to Colombia. And so it must also be the year of this televised leaders climate debate – if not now, when?

With Channel 4 agreeing to host the debate as early as next week, the only thing missing is an agreement from the one major party leader who is so far refusing to take part: Boris Johnson.

Our demand now is very simple. Johnson must reverse his decision to snub this unprecedented debate and show that his party has more than reusable straws and drinks stirrers as a response to the greatest crisis of all time.

A climate debate between leaders befits the gravity of this situation.

Failing to show up for it won’t just make the prime minister a “climate chicken” – it will reveal his utter contempt for the many, many people in the UK and abroad who are facing this desperate climate emergency and looking to our leadership for answers.