Around the world, from Alaska to Indonesia, more than 200 ancient myths tell of a human civilisation brought to an end by flood and fire.

Compelling scientific evidence, which began to emerge only in 2007, indicates that these stories, such as the tale of Noah and his Ark, are based on hard fact.

A cataclysm rocked our planet 12,800 years ago, causing mass extinctions of large animals such as the mammoth and sloth bears, and all but wiping out our own race. An entire episode in the human story was rubbed out, a chapter not of unsophisticated hunter-gatherers but of advanced technology.

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Extinction Level Event? Within the next 20 years, Earth faces a collision with the remnants of a comet big enough to end all life as we know it, according to the author of Magicians of the Gods Graham Hancock

All the signs are that remnants of this civilisation struggled on, sustained by a few individuals who knew the secrets of the former age. To their primitive contemporaries, it appeared that they possessed magical, holy powers — they were what I call the Magicians of the Gods.

These Magicians left a message for us — not a metaphorical, spiritual message, but a direct and urgent warning. What happened before can happen again; what destroyed their world can destroy ours.

Those warnings have gone unheeded for millennia. Now, we have the scientific evidence to decode them, but it is almost too late.

Within the next 20 years, Earth faces a catastrophe a thousand times worse than the detonation of every nuclear weapon on the planet — a collision with the remnants of a comet big enough to end all life as we know it.

To understand what that could mean, we need to look back at the tumultuous epoch between 10,800 BC and 9,600 BC, which geologists call the ‘Younger Dryas’.

This was a time of extraordinary shifts in the world’s climate. But the most devastating change of all came when the ice caps suddenly collapsed, dumping all the water they contained into the oceans and unleashing a tsunami that swept across continents.

As we’ll see, all the evidence suggests this was the result of a comet crashing into Earth.

Many Native American tribes describe the devastation in tales passed down through the generations.

Devastation: A cataclysm rocked our planet 12,800 years ago, causing mass extinctions of large animals such as the mammoth and sloth bears, and all but wiping out our own race, Hancock writes

The Brulé people of the Lakota nation in modern-day South Dakota have a vivid legend of a ‘fiery blast [that] shook the entire world, toppling mountain ranges and setting forests and prairies ablaze . . . Even the rocks glowed red-hot, and the giant animals and evil people burned up where they stood’.

After the fiery destruction came the floods: ‘The rivers overflowed their banks and surged across the landscape. Finally, the Creator stamped the Earth, and with a great quake the Earth split open, sending torrents . . . across the entire world until only a few mountain peaks stood above the flood.’

This is not an isolated myth. The Cowichan of British Columbia, the Pima of Arizona, the Inuit of Alaska and the Luiseno of California have similar stories. But it is the Ojibwa, people of the Canadian grasslands whose legend seems the most credible, almost scientific, today.

Their storytellers remember a comet called Long-Tailed Heavenly Climbing Star which swept low through the skies, scorching the Earth and leaving behind ‘a different world. After that, survival was hard work. The weather was colder than before.’ And the Ojibwa believed this was just a foretaste of an apocalypse to come.

A fiery blast shook the entire world, unleashing a tsunami

They spoke of a stark prophecy, foretold by their medicine men: ‘The star with the long, wide tail is going to destroy the world someday when it comes low again.’

It was not until the 20th century that scientists even began to consider the possibility that ancient American myths might be based on real events.

J. Harlen Bretz, a noted geologist in the Twenties, began to investigate the notion of a prehistoric flood when he discovered hundreds of ‘erratics’ — colossal boulders that didn’t belong in the landscape — scattered across the rocky Scablands of Washington state. Bretz examined a colossal feature, a 600 square mile depression filled with basalt silt 400 feet deep.

He saw only one explanation: it was scoured by a spectacular flood that had ended as abruptly as it began.

Amateur geologist Randall Carlson has taken up Bretz’s work, and he took me to Dry Falls in Grant County, Washington, to see the most spectacular evidence of the deluge.

The waterless falls are on the Grand Coulee, a sheer-sided gash, hundreds of feet deep and almost 60 miles long, which looks as though the hand of God has seized a chisel and ripped it along the landscape.

This chisel was not made of metal but of immense quantities of turbulent, debris-laden water that flowed for just a few weeks.

Best-selling author: Magicians of the Gods, by Graham Hancock, is published by Coronet at £20

In all directions across the prairie, it has left millions of jagged basalt boulders, some no bigger than a football, others the size of a family car. Dry Falls itself is close to three times higher than Niagara and around six times as wide. The waters 12,800 years ago that carved out this vast cliff, Randall says, were ‘more like a slurry of thick mud. There’s whole forests torn up by their roots roiling around in it, and fleets of icebergs jostling on the surface, and this whole mess is plucking blocks out of the basalt bedrock, dragging them into the torrent and sweeping them downstream.’

It might have been the biggest flood, but it was far from the only one. Oceans of ice melt had been unleashed around the world.

Like me, Randall believes the most probable explanation for this deluge, literally of Biblical proportions, was a comet impact — just as the Ojibwa described. A giant comet travelling on an orbit that took it through the inner solar system broke up into fragments and some of these, including up to four objects more than a mile across, smashed into the Cordilleran and Laurentide ice caps covering northern America in 10,800 BC.

The heat of these monster meteorites melted the ice. But they also threw vast clouds of dust and sooty smoke into the upper atmosphere, blotting out the sun.

That sent temperatures plunging across the Earth and initiated a new Ice Age that lasted 1,200 years.

This is not mere speculation and hypothesis. In September 2014, the Journal Of Geology presented a mass of evidence confirming the copious presence of so-called nanodiamonds in samples from the Younger Dryas boundary layer.

The boundary layer is the deposit laid down by a geological event. It can be seen, for instance, as a stratum in rock.

Nanodiamonds are microscopic gems that form under rare conditions of great shock, pressure and heat, and are recognised as signs of powerful impacts by comets and asteroids.

The big question was not whether there had been a comet strike 12,800 years ago, but why there was no crater.

The explanation is simple: while smaller, low-density particles of the comet would have exploded in the atmosphere, the larger fragments hit the two-mile ice caps. The craters they left simply melted away at the end of the last Ice Age. That long winter is remembered in many legends and sacred texts.

The Zoroastrian religion in the near East, for example, speaks of a ‘fierce, foul frost’ and a ‘fatal winter’ inflicted on the whole Earth by an evil spirit who ‘made the world as dark at midday as though it were dark night’.

On the other side of the world, the ancient Quiche Maya people in Guatemala spoke of a flood with ‘much hail, black rain and mist, and indescribable cold’.

But the texts also tell of leaders who arrived in the wake of the disaster, armed with exceptional knowledge. These are the people I call the Magicians of the Gods.

They understood how to construct buildings on a grand scale, how to organise and govern and how to engineer tools of remarkable sophistication. Some of the technology they describe appears to rival modern electronic wizardry.

Temperatures plunged, starting a new Ice Age

The Zoroastrian’s wise man, Yima, was said to possess a miraculous cup in which he could see anything that was happening anywhere in the world, and a jewelled glass chariot that could fly.

In carvings uncovered at ancient sites as far-flung as Turkey and Mexico, these wise men are depicted in strangely similar costumes: they are bearded men, holding a bag or bucket with a curved handle, with the heads of birds or fish.

The Babylonian priest Berossus, writing in the 3rd century BC, described a mythical figure who arrived in Mesopotamia. His name was Oannes and he had ‘the whole body of a fish, but underneath and attached to the head of the fish there was another head, human. Joined to the tail of the fish [were] feet like those of a man, and it had a human voice.’

It sounds very much as if Oannes was a human being, wearing an elaborate fish costume that might have been holy robes or merely a piece of showmanship.

At the semi-subterranean temple of Tiahuanaco in western Bolivia, South America, similar shamanic figures are depicted wearing garments from the waist down patterned in fish scales.

Experts disagree over the age of these carvings, but they do also show animals that appear to be toxodons — gigantic, rhino-like animals that became extinct around 12,000 years ago.

The Magicians of the Gods, it seems, roamed all over the world.

In the Middle East, Oannes was accompanied by seven sages, who are repeatedly described as conjurors, sorcerers, warlocks and magicians, who were masters of chemistry and medicine and who understood carpentry, stone-cutting and metal-working.

Evidence suggests that a tsunami between 10,800 BC and 9,600 BC was the result of a comet crashing into Earth. Pictured is an aerial view of Kamiishi city in Japan which was hit by a tsunami in March 2011

Magicians such as these also turned up in Egypt at the same time. At the Temple of Horus in the Egyptian city of Edfu, inscriptions known as the Edfu Texts describe god-like beings who were refugees from a sacred island that was destroyed by flood and fire.

Their home, the ‘mansions of the gods’, was utterly destroyed and their civilisation wiped out, but a few survivors had, luckily, been at sea when the disaster struck.

They set sail in ships to wander the world, with one purpose: to reinvent their homeland. As the Edfu Texts recorded, their goal was ‘the resurrection of the former world of the gods’.

The seven sages who arrived in Egypt understood how to lay foundations and plan the construction of buildings. They were so steeped in knowledge that the primitive people who revered them believed they were wiser and more powerful than their own old gods.

Arab tradition says that the secrets of this technology were buried in the pyramids at Giza millennia later.

The 9th-century historian Ibn Abd El Hakem believed the pyramids were designed not as tombs, but as places of safekeeping for books of knowledge dating to before the Great Flood.

These books contained ‘profound sciences, and the names of drugs and their uses and hurts, and the science of astrology, and arithmetic and geometry and medicine . . . arms which did not rust and glass which might be bent but not broken’.

That evidence of a civilisation far older than the Babylonians and the Egyptians, a civilisation that was all but destroyed by a comet 12,800 years ago, has long been lost.

But there are other historic sites, just as breathtaking as the pyramids but much less known.

Nothing less than an interplanetary hand grenade

One is Gobekli Tepe, which literally means Potbelly Hill, in Turkey. It is the oldest work of monumental architecture in the world and it is massive.

It is here, according to the late archaeologist Professor Klaus Schmidt, that neolithic man discovered farming. It is also the place where ancient humans first tackled megalithic stone carving, erecting pillars that weighed 20 tons. This is architecture on the scale of Stonehenge, but far more sophisticated — and, while Stonehenge is generally reckoned to be 4,600 years old, Gobekli Tepe is at least 12,000 years old.

Bizarrely, as far as archaeologists can tell, the astonishing strides in human development made at Gobekli Tepe came out of nowhere. It’s as if its people quite suddenly ‘invented’ both agriculture and monumental architecture at the same moment.

Now, it seems unthinkable that primitive hunter-gathers could suddenly dream up all the technology and know-how required, without any process of experimentation.

Surely Gobekli Tepe is powerful evidence of knowledge imparted by a prior civilisation.

But the site is also significant for a far more ominous reason.

Complex zodiacal signs are inscribed on one of its limestone pillars, incorporating astronomical data supposedly not discovered until thousands of years later.

Even more puzzling is the position of the stars — not quite where they would have been in the sky 12,000 years ago . . . but exactly where they are today.

It is as though these mysterious, impossibly learned builders constructed their temple as though it existed in the present day.

The Magicians of the Gods were trying to get a message to us, here in the 21st century, writes Graham Hancock. We need to listen

The Magicians of the Gods had a message for our times, and it is not one we can afford to ignore.

The explosive power of the Younger Dryas comet was in the order of ten million megatons, two million times greater than the biggest nuclear bomb detonated and 1,000 times more powerful than all the atomic devices stockpiled on Earth.

But when the Earth emerged from the path of the comet’s debris stream 12,800 years ago, that was not the end of the story.

My intuition is that the Gobekli Tepe pillar is a coded message to the future — our present — about a second impending comet strike.

As long ago as 1990, well before the discovery of physical evidence that proved the Younger Dryas Ice Age was caused by comet fragments colliding with the Earth, two far-sighted British scientists were sounding the alarm. Astrophysicist Victor Clube and astronomer Bill Napier believe that a giant unseen comet is now careering towards us through space. It is concealed within a cloud of cosmic debris, known to astronomers as the Taurid meteor stream.

This poses a double danger: we could be hit by any one of the millions of space rocks in the stream, or by much larger pieces of the unseen comet itself, if and when it explodes.

And it could explode at any moment. It is nothing less than an interplanetary hand grenade.

Sealed within its thick shell is a seething mass of pitch-like tar, which will gradually build up pressure until, like an overheated boiler with no release valve, the comet will detonate and shatter into fragments, a mile wide or more, tearing through the solar system at tens of thousands of miles an hour.

We cannot guess exactly when that explosion will occur.

It could happen as we re-enter the meteor stream, or shortly before, strewing our planet’s path with hurtling boulders.

All we can know for certain is that, in around 15 years, the Earth will once again cross the Taurid meteor stream, that vast highway of cosmic debris, right at the place where the biggest and most numerous fragments that currently exist are collected.

Some of them are three times the size of the asteroid that hit the planet 65 million years ago, setting off a global firestorm and bringing about the extinction of the dinosaurs. This is when the risk of a collision is most severe. This is when the prophecy of the Ojibwa people is set to come true: ‘The star with the long wide tail is going to destroy the world someday when it comes low again.’

We can’t say that we weren’t warned. The Magicians of the Gods were trying to get a message to us, here in the 21st century. We need to listen.