The resulting changes in temperature and radiation levels may have killed many large mammals.

This event may eventually lead to the extinction of Neanderthals.

42,000 years ago, there was a huge vibration when the earth's magnetic pole turned over.

Scientists have known about this flip since the late 1960s. The earth's magnetic poles are not static-they are generated by the current generated by the earth's liquid outer core, which is always moving. Recently, the North Pole of the Earth has moved to the north of Russia to a considerable extent.

But in most cases, scientists don't think that the last polar flip will have a significant impact on the environment. Of course, the magnetic field of Mars has weakened, allowing more cosmic rays to penetrate the atmosphere, but the lives of animals and plants have not been greatly affected.

Now, a new study shows that a more dramatic phenomenon has occurred: extra cosmic rays may have exhausted the concentration of ozone and opened the floodgates for more ultraviolet radiation in the atmosphere. Changing weather patterns may have expanded the ice sheet in North America, made Australia dry and led to the extinction of many large mammals. At the same time, solar storms may force ancient humans to seek refuge in caves.

With the intensification of competition for resources, our close relative Neanderthals may also become extinct.

Chris Turney, a geoscientist at the University of New South Wales, said in a video describing the new study, "This will be a very terrible period, just like the end of the world."

Scientists haven't come up with a clear theory about the reason why Neanderthals disappeared. Some studies show that their extinction happened naturally, because Neanderthals inbreeded with modern people, or because the population was too small to hunt, mate and raise offspring. Other scientists speculate that as modern humans began to migrate to Europe, Neanderthals may be at a disadvantage in resource competition.

But Tanny's research shows that it may not be a coincidence that Neanderthals died out after major changes in the earth's magnetic poles.

"Only when you start to discuss the relationship between different scientific fields will you find the connection," said his co-author, Allen Cooper. "Before this, it was not found to be a key event in different research fields (42,000 years ago)."

Ancient trees and caves provide clues to possible climate disasters.

In order to find out what happened to the earth's climate 42,000 years ago, scientists asked a New Zealander who lived in that era: GuCowley. Tree rings are records of radioactive carbon content (a radioactive isotope) in the atmosphere for tens of thousands of years. In fact, these rings show evidence that radioactive carbon rises when the magnetic field flips. This phenomenon is called "Rasmussen drift".

This event is not uncommon in the history of our planet: the British Geological Survey estimates that there will be four to five pole shifts every one million years.

During these reversals, the magnetic shielding that protects our planet from the solar wind (charged particles from the sun) will be weakened. The geomagnetic north and south poles of the earth-not to be confused with the northernmost and southernmost geographical points of the earth-are interchangeable.

The trip to Laschamps, the latest example of this polarity reversal, may have happened in 1000. This is only a short moment in the life of the earth, but it is enough to change the fate of people living on the earth.

Tanny said: "In the process of turning from north to south and from south to north, the earth's magnetic field almost disappeared." "It opened the door to all these energetic particles from outer space."

Neanderthals may need to find shelter if the sun releases ultra-high levels of radiation in solar storms.

In fact, Laschamps' hiking coincided with the increase in cave use in Europe and Southeast Asia. In particular, researchers found ochre handprints dating back to 40,000 years in caves in this area. According to this new study, this pigment may be an ancient sunscreen.

Another pole shift may be "imminent"

Not all researchers believe Tanny and Cooper's analysis. Chris stringer, an anthropologist at the Natural History Museum in London, told the Guardian that although Lashawn's hiking may have led to the death of Neanderthals, it is difficult to know exactly when they became extinct.

Stringer said: "They really live longer and are more widely distributed than Europe. We are very uncertain about when they will eventually disappear in a large area of Asia."

James Chanell, a geologist at the University of Florida, told NBC that the history of ice cores can be traced back to 42,000 years ago, which does not mean a global climate crisis. However, he added that there "seems to be some connection" between the extinction of large mammals and the weakening of the earth's magnetic field.

At the very least, this new study provides a clue to what will happen if the north and south magnetic poles flip again.

Scientists know that in the past 170 years, the earth's magnetic field has weakened by about 9%. Since 1990s, the drifting speed of the Arctic magnetic field has been accelerating, moving at a speed of 30 to 40 miles every year.

The researchers wrote that this "increased speculation that a magnetic field reversal might be imminent". Such an event may subvert the power grid and satellite network. The increase in radiation will also expose more people to diseases such as cancer.

But scientists suspect that any possible magnetic field reversal is still in its early stages. The earth's magnetic field is still much stronger than the last magnetic pole flip.