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.
Recent Israeli Synagogue Attack, a Possible False Flag? 2014 11 21 Dear Friends - I woke up yesterday morning to see a newspaper lying on the kitchen table with the front page proclaiming that five people were slain in an Israeli synagogue after a so-called "Palestinian attack." Some members of the media said that four people were killed, others said five, so it seems like that there was some confusion (or ...
Detekt: A New Malware Detection Tool That Can Expose Illegitimate State Surveillance 2014 11 21 Recent years have seen a boom in the adoption of surveillance technology by governments around the world, including spyware that provides its purchasers the unchecked ability to target remote Internet users’ computers, to read their personal emails, listen in on private audio calls, record keystrokes and passwords, and remotely activate their computer’s camera or microphone. EFF, together with Amnesty International, ...
New UK spy chief says tech giants aid terrorism, privacy not ‘absolute right’ 2014 11 21
Robert Hannigan, the new head of GCHQ
The new head of Britain’s GCHQ, the UK equivalent of the NSA in the U.S., said he believes privacy is not an absolute right and that tech giants must open themselves up to intelligence agencies.
“GCHQ is happy to be part of a mature debate on privacy in the digital age,” Hannigan said. “But privacy ...
LOL: Atheist Feminist Pornographer Used as Moral Authority in T-shirt Row 2014 11 21
Dr. Matt Taylor was thrust into the headlines this last week, largely for his lead role in successfully landing a spacecraft on a comet 300 million miles from earth that travels at a speed of 85,000 mph. In short, Taylor and his colleagues pulled off one of the most amazing achievements in contemporary science and space exploration, and in a ...