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.
Aurora Shooting Victim Parents Face $200K Court Fees, Bankruptcy, After Failing to Sue Ammo Dealers 2015-08-01 2:17
The 2012 Colorado Theater Shooting still doesn’t add up…
Media character and ‘Shooter’ James Holmes in court in 2012-2013.
In 2014, Sandy and Lonnie Phillips, the mother and stepfather of Aurora Theater Shooting victim Jessica Redfield Ghawi, tried to sue the ammo companies they believe supplied shooter James Holmes with his ammunition, body armor and other items. They bleived that the online retailer BulkAmmo.com had sold Holmes ...
FBI's Joint Terrorism Task Force Investigating Confederate Flags at MLK's Ebenezer Baptist Church 2015-08-01 2:21
According to the Atlanta Police Department, two White men left four small Confederate Battle Flags outside MLK’s Ebenezer Baptist Church in Atlanta … and get this, the FBI’s Joint Terrorism Task Force is on the scene investigating the incident.
Atlanta police Chief George Turner said his agency was working with federal authorities and they have not determined what charges might be ...
Catching on slow: Yet Another Study Show Cellphone Radiation Cause Cancer 2015-08-01 1:44
The scientists were right — your cell phone can give you cancer.
There have long been whispers of a cancer connection from your cell — and a new study backs up the claims.
"These data are a clear sign of the real risks this kind of radiation poses for human health," study author Igor Yakymenko said.
Yakymenko’s meta-study — basically a study of ...
Trump Goes #Cuckservative on Immigration 2015-08-01 1:28
For weeks, the media have trumpeted the supposed death of the Trump campaign. First, they claimed, Trump’s campaign imploded on launch thanks to his comments about illegal immigration. Then they claimed that Trump was finished because of his slap at Senator’s (R-AZ) war service. But neither of those comments alienated Trump’s base – he’s maintained his seven point lead over ...