Earth’s magnetic field reversed extremely rapidly soon after modern humans first arrived in Europe, completely flip-flopping in less than a thousand years, new research suggests.
These findings, detailed Oct. 15 in the journal Earth and Planetary Science Letters,could shed light on how and why magnetic field reversals happen, and how they leave Earth vulnerable to solar and space radiation, the study scientists said.
Earth’s metal core acts like a giant magnet that emanates a magnetic field with two poles, north and south. These two magnetic poles very roughly match where the planet’s geographic north and south poles lie, which mark the axis on which Earth spins.
The Earth’s magnetic field, magnetic poles and geographic poles.
"The Earth’s magnetic field is a highly dynamic feature," said researcher Norbert Nowaczyk, a paleomagnetist at the GFZ German Research Centre for Geosciences. "Its intensity pulsates between values 50 percent higher than today, or 90 to 95 percent lower than today."
In addition, every several hundred thousand years, Earth’s magnetic field reverses — a compass that would have pointed north would instead aim south. These flips are captured by magnetically sensitive minerals in cooling lava that are literally set in stone pointing to where the poles were at that particular moment in Earth’s history.
Full reversals of the magnetic field usually take millennia to finish, based on those frozen rock records. However, scientists now find that 41,000 years ago, shortly after modern humans first entered Europe, the magnetic poles flipped and flipped again in less than a millennium.
Scientists analyzed data in sediment from the floor of the Black Sea and compared it with other data from the North Atlantic, the Southeast Pacific and around Hawaii. Surprisingly, they found the Earth’s magnetic field took about 200 years to flip, during which time it was just one-twentieth as strong as it is today.
"Former ideas about a field reversal deal with durations of 2,000 to 5,000 years," Nowaczyk told OurAmazingPlanet.
Earth’s magnetic field stayed reversed for only 440 years, during which time it was just one-quarter as strong as it is today. The magnetic poles then flipped back to approximately where they were before over the course of about 270 years. The flip-flop overall is known as the Laschamp event, after the area in France where evidence of it was first discoveredin the 1960s. These new findings reveal how quick this reversal was.
The brevity of this flip overall suggests "it might represent a so-called aborted reversal," Nowaczyk said. "This means the geomagnetic field tried to reverse, but fell back." Such aborted reversals, also known as excursions, may have happened at least a dozen times during the last 780,000 years since the last full reversal, he explained.
Magnetic field shield
Earth’s magnetic field helps protect the planet from energetic particles streaking out from deep space and the sun. During the Laschamp reversal, Earth was significantly more vulnerable to radiation from space, judging by higher levels of radioactive beryllium seen in ice samples from Greenland, Nowaczyk said.
Such radiation poses a particular threat in our modern world, so understanding these reversals is helpful to better understand the threats from space.
"Communication and GPS satellites might be damaged when the cosmic rays are less shielded by the geomagnetic field," Nowaczyk said. "Therefore, it is important to know how dynamic the geomagnetic field is in time and space. We need to know how fast changes in intensity, and thus shielding ability, can happen."
Earth’s magnetic field is generated by the roiling of its outer liquid core. Research suggests that at times this outer core can behave as many magnets instead of one. These magnets can, in principle, cancel each other out, causing the magnetic field overall to weaken or flip.
"We need more data from more sites of the same reversal to get a better understanding of these processes," Nowacyzk said.
The Ring of Brodgar, the Neolithic Henge of Orkney Island 2014 03 06 On the largest island of Orkney, Scotland called The Mainland, amongst the rugged cliffs and almost constant wind, there sits a Neolithic henge and stone circle known as The Ring of Brodgar. It is the third largest circle in the British Isles after Avebury & Stonehenge. Built in a true circle, the Ring of Brodgar is thought to have been ...
Ancient Egyptian Soldier’s Letter Home Deciphered 2014 03 06 A newly deciphered letter home dating back around 1,800 years reveals the pleas of a young Egyptian soldier named Aurelius Polion who was serving, probably as a volunteer, in a Roman legion in Europe.
In the letter, written mainly in Greek, Polion tells his family that he is desperate to hear from them and that he is going to request ...
Creator of Bitcoin Has “Done Classified Work for Major Corporations and the U.S. Military” 2014 03 06 The picture that’s painted here is pretty strange. Nakamoto apparently worked on black world projects, but, according to the story, he’s a libertarian and is ambivalent about the government. According to his daughter, “He was very wary of the government, taxes and people in charge.”
I don’t know what to make of this, but it’s definitely an interesting read.
Satoshi Nakamoto ...
Meet the only man that George W. Bush ever ‘pardoned’ – but why? 2014 03 06 21st Century Wire says…
When George W. Bush was governor of Texas, something very, very bizarre went down, and to this day, neither the mainstream press, or the alternative media have made much headway on this strange turn of events…
The investigation focuses around what links Bush, his family or inner circle, had with the convicted serial killer and self-proclaimed cannibal and ...
Admitted Spy Shows Up for Oscars – and Wins 2014 03 06 And the winner is … Arnon Milchan!
Though Milchan, an Israeli citizen, admitted in November that he engaged in espionage against the U.S for many years, including helping to smuggle American nuclear bomb parts to Israel, his appearance at the Oscars was pretty much proof not all spies are treated equally.
Forbes columnist Dorothy Pomerantz, who writes about Hollywood for the magazine, ...