With Christmas upon us we take you to the abode of climate activist professor Ebenezer Kluge, sitting comfortably in his well-heated and brightly-lit home contemplating how much happier the poor must be without all those nasty fossil fuels, home appliances and other burdens of modern life. But suddenly an ominous clanking is heard and a spectre bursts into his living room, the ghost of his recently-deceased colleague Jacob Modeler, shaking a massive spectral chain of fudged data sets, retracted papers and angry hyperbole beseeching him to change his ways while there is still time. Kluge protests that his old colleague was always a reliable man for the cause, only to elicit an agonized cry that “research was my cause; its integrity was my cause” followed by a disquieting declaration that three spirits would visit Kluge before morning, those of climate past, climate present and climate yet to come, and he’d better listen up. Then the Ghost vanished out the window, showing Kluge the forlorn spectres of deceased scientists who were trying to look up actual facts and contest absurd hyperbole but had lost the power to do so.

Brushing it all off as denialism, Kluge retired to his lavish bedchamber in a penthouse apartment high above a glittering city, shaking his head at all the electricity others were wasting, and drifted off with visions of heat pumps dancing in his head. But before he could get into real REM sleep a soothing persistent voice awakened him, and proved to emanate from a scholarly figure in a flowing robe bathed in soft light.

“Who or what are you?” Kluge stammered, and the gentle reply was “I am the spirit of climate past.” “Long past?” “Earth’s past.” And taking his sleeve with subtle persistence the spectre told his uneasy travelling companion, “You have spoken often of ‘pre-industrial times’. Let us now visit them, but remember, we are but ghosts, they cannot see us, burn us up or eat us.”

With that they appeared in the Hadean Epoch when the Earth was a blazing fireball, then toured through various snowball Earths and into the time of the dinosaurs. One dramatic change followed another, each more marvellous than the last, and forgetting himself, Kluge clapped his hands delightedly at the giant apatosaurs and stegosaurs, though he was much relieved to find that the Spinosaurus could indeed not see or chomp them.

With the youthful enthusiasm that had first brought him into science, he praised the glorious scenes before them. “Yet it is considerably warmer than today, is it not?” the spirit asked. “Oh, it isn’t that,” Kluge responded. “It’s the variety, number and size of these marvellous creatures and the lush ecosystem, almost as if…” his voice trailed off.

“What?” the spirit prompted him. “Nothing,” he mumbled. “Something, I think.” “It’s just that it seems that here at least the warmth didn’t create a runaway disaster. I’d like to have a word with my research assistant now.”

The spirit waved its arm and the scene shifted, to a planet still warm but without dinosaurs. Here came marvellous mammals, including giant sloths, Paraceratheria and species after species including cats, dogs, and monkeys, all cavorting in the warmth.

Kluge sighed. “These are amazing,” he said. “But somehow nothing ever quite compares to the dinosaurs.” “Indeed,” said the ghost. “And now the planet is cooling.” With that, and another wave of the hand, the Eocene gave way to the Oligocene and then, as if from nowhere, the Pleistocene. Great ice sheets rolled across the northern hemisphere, species fled or faltered, and a barren landscape brought forth its own wonders including woolly mammoths and the improbable and scary saber-tooth tigers. Before he could stop himself Kluge muttered “The cold is quite barren” then clapped a hand across his mouth.

Then came the Holocene, and they stood on the northern shore of Africa, where giraffes and hippopotamoi frolicked amid green rushes and flowing rivers. Man appeared too, and writing, and metal, and the Iron Age cooling when barbarian invasions laid Troy waste. The warmth returned and Rome flourished; it faded and the Dark Ages came; it returned and the Middle Ages saw a spectacular revival of agriculture, architecture and learning, before the bitter cold of the Little Ice Age brought the glaciers down from their alpine retreats, crops failed, and war and revolution spread terribly.

Just as James Watt perfected his new and improved steam engine, and he thought he heard the spirit say something about “The Industrial Revolution actually started in 1776” Kluge found himself in bed asleep.

Not for long. He was awaked by a hearty roar of “Data! Data!” and scrambling from his bed and out into his dining room he found it occupied by a giant in a robe embroidered with numbers, surrounded by vast piles of papers, satellites and measuring sticks. “Come closer, man, come closer” it roared, “and know me better. You’ve not seen the like of me before, have you?” Leaning weakly on the mantlepiece, Kluge replied “No, and I wish the pleasure had been indefinitely postponed.”

“What’s that?” the spirit bellowed. “But how can you know if all the claims you make, and accept, are true if you do not feast on the information, plunge into the facts, embrace and revel in actual knowledge, measurements and reliable series?”

“Oh, such a ruckus,” Kluge protested. “Everybody knows that hurricanes are getting worse, the seas are rising, wildfires are consuming everything, floods and droughts are out of hand, it’s warmer today than in pre-industrial times uh that is…”

Yet again his sleeve was grasped by a persistent spirit, and he was whirled across the globe, shown country after country that was not warming faster than the average, detailed records of the number of cyclones and their accumulated energy, and rather more distressingly a scholar named ignorance who had no idea how the supposedly reliable datasets were cobbled together from dubious tree rings, uncorroborated or calibrated satellite numbers and sheer brazen invention, and then to an IPCC gathering where politicians wrote their own “Summaries for Policymakers” fit to drive the authors of the supposedly underlying science to Bedlam.

The spirit also showed him brave and happy researchers in their laboratories looking into what really happened, what and how much they really knew, and welcoming rather than suppressing unexpected findings. Including one really annoying kid who… but why spoil the mood?

Why indeed. Kluge instead found himself abandoned outside the gates of a university on a bleak December night, confronted with an ominous shadow in black crepe. “Are you the ghost of climate to come?” Kluge asked in a trembling voice. The shadow gave no answer and without seeming to move they appeared in Kluge’s old office. But it was now dark, cold and dusty, the computer unplugged and the nametag gone. The entire building was dark, in fact, and with a sudden rush they found themselves in the town square and it too was deserted, grimy, with scraps of debris and rats the only things moving.

“Spirit, what happened? Was there a nuclear war? Did Donald Trump get a third term? Did someone restore the traditional family? Did AI take over?” Cold and implacable, the spirit spoke not a word, but pointed to a piece of newspaper that had blown across the asphalt and come to rest against its leg. “City shuts off fossil gas!” it proclaimed. “Solar power and green hydrogen for all, governor declares!”

Before Kluge could protest, the spirit drew its dark garment across his face, and they stood again in Africa. But surrounded not by plenty and life, but by skeletons of animals, trees and plants, the ground mere dust. Then it thrust another headline into his face: “Carbon capture works! Geoengineering reflects sunlight! Scientists reverse global heating!” And with that, they were again at his old office building, but now a glacier was thrust through its teetering structure.

“Oh spirit,” he cried. “Tell me the planet’s not already dead. Tell me there’s still time to change the direction we’re heading.” The spectre responded with a singularly nasty laugh, and they stood in the balcony of a legislature with a gaggle of politicians bearing a remarkable resemblance to geese hissing and cackling mindlessly. It went on for some time but nothing actually happened.

Just as nausea overcame him, Kluge found himself yet again in his bedroom, in his cozy bed, the sun just rising, casting glorious light and warmth upon his window. Leaping up he rushed out onto the balcony, felt dawn glow upon his face, and cried out with delight that glorious, life-sustaining heat was here and that spring would return.

And from that day forward, he debated respectfully with colleagues, included error bars in all his charts, and wrote indignant letters to newspapers when idiotic climate hyperbole got printed as sober fact. He lost a few friends he realized he’d never much liked, but got back his self-respect, and never regretted the bargain.