Christmas in York is traditionally a time for charity and helping those worse off than ourselves. Street collections in St Helen’s Square, carol singers rattling buckets for spare change, meals laid on for our ever-growing number of homeless citizens.

This festive season, however, we have a new priority for extra tender loving care. I mean, planet Earth.

Earlier this month one of Britain’s most trusted naturalists and broadcasters – and a good friend of York’s very own Yorkshire Museum – delivered the starkest of warnings.

Sir David Attenborough told a UN climate change summit in Poland the collapse of civilisation and the natural world is inevitable unless we, as a species, change our ways. He had the honour of being chosen to represent the world’s people in addressing delegates of almost 200 nations gathered in Katowice to negotiate how to turn pledges made in the 2015 Paris climate deal into reality.

“Right now we are facing a manmade disaster of global scale, our greatest threat in thousands of years: climate change,” he said. “If we don’t take action, the collapse of our civilisations and the extinction of much of the natural world is on the horizon.”

Attenborough also made a telling point about leadership: “The world’s people have spoken. Time is running out. They want you, the decision-makers, to act now. Leaders of the world, you must lead. The continuation of civilisations and the natural world upon which we depend is in your hands.”

His point was clear. In democratic societies, at least, it is we, the ordinary people, who should be forcing our leaders to take immediate action on this life or death issue. After all, the science of climate change catastrophe is absolutely not in doubt, except perhaps for a few greedy, selfish individuals and politicians connected to the fossil-fuel industry or ‘flat-earther’ cranks.

A seasonal example could be found in Lapland, Santa’s traditional stomping ground. What you won’t find in December 2018 is Santa stomping through the snow. There is no snow. A weirdly hot summer and autumn have morphed into an unseasonably warm winter.

The evidence is incontrovertible: humanity’s addiction to burning fossil fuels is raising the temperature of the planet to dangerous levels. Even as you read this, the ice caps are melting. And, by the way, if you get a Christmas card featuring a cute polar bear, enjoy it. Because polar bears are now becoming an endangered species, at risk of being wiped out like the dodo by human beings, along with thousands of others species.

According to the UN’s rigorous scientific evidence, action to tackle climate change must be increased fivefold to limit global warming to 1.5C. The UN’s recent IPPC report proved that any rise over 1.5C will have catastrophic effects – and time is running out, with just twelve years before a 2C rise if we do nothing.

As Christmas and the New Year draw near, every one of us should consider what role we can play in averting this disaster. Apparently small, individual decisions, when added to millions of others’ choices, can have a powerful effect. For example, are hundreds of blazing, winking electric lights essential for an enjoyable Christmas? Do piles and piles of consumer goods in the form of presents wrapped in shiny, instantly disposed paper really make us happier? The best present we could give ourselves this year is helping the natural world recover.

David Attenborough is absolutely right to point the finger at our leaders, local and national, who all too often frame the political debate to avoid meaningful climate action. To take one example, restricting car use risks alienating many voters, even though we all know it is absolutely essential.

In May 2019 the people of York will get a chance to choose their council in the local elections. I desperately hope that truly transformative and ambitious policies to address the climate catastrophe will be on offer. To paraphrase David Attenborough’s UN conference speech: “Leaders of York, you must lead.” To be worthy of our votes, local politicians need to plan for genuine and effective change, not fudge, before it is too late.