A new study has revealed that the geomagnetic field, which scientists warned regarding hundreds of years ago, will not suddenly flip.
It now appears that the magnetic north pole will be in the north and the magnetic south pole will be in the south – at least for a few thousand years or so.
“We are currently in a period of a very strong geomagnetic field from a geological time perspective,” Andreas Nilsson, a geologist at Lund University in Sweden, said in an email. “There is a long way to go before the polar shift.”
Nielsen is the lead author of the study Released this month The National Academy of Sciences has studied a major weak spot in the geomagnetic field known as the South Atlantic Anomaly, or SAA.
The study indicates that the Earth’s magnetic field is gradually weakening from the beginning Geomagnetic parameter Founded in the 1840s, the SAA’s weakness has grown even larger during that time.
This has led some scientists to theorize that the strength of Earth’s magnetic field is decreasing before it completely reverses trend – something it has done many times in the past, laid by rock layers over millions of years to show past reversals.
But new research finds that large geomagnetic anomalies have occurred before, and relatively recently in geologic time, without causing the field to change.
These anomalies usually disappear following a few hundred years — and there’s no indication that SAA will be any different, Nielsen said.
Nelson and his colleagues studied how Earth’s magnetic field has changed over the past 9,000 years by looking at iron in volcanic rocks, ocean sediments, and sometimes burnt artifacts.
They include clay pots fired in ancient kilns tens of thousands of years ago, and sometimes contain small amounts of an iron ore called magnetite. The magnets lost their alignment during the firing process, Nelson said, and the granules were re-magnetized by the Earth’s magnetic field as they cooled, recording the strength of the field.
The study shows that the current state of the Earth’s magnetic field is similar to that of 600 BC, when it was dominated by two major weak points in the Pacific Ocean.
Over the next 1,000 years, the anomalies over the Pacific Ocean will disappear, Nielsen said, and so will the SAA — perhaps in regarding 300 years, leaving behind a much stronger and more powerful Earth’s magnetic field.
The geomagnetic field reversal would probably not be catastrophic, but it would certainly be uncomfortable.
Scientists believe this field is formed by the flow of molten iron in the Earth’s core, regarding 1,800 miles below the surface. It serves as a shield once morest deadly solar radiation, and makes magnetic compasses work.
Geological studies indicate that the Earth’s magnetic field has reversed 10 times in the past 2.6 million years alone. The last event occurred regarding 780,000 years ago – the so-called Brunhes-Matuyama reversal event.
But while the process is linked to movements in the molten core, it’s not well understood — and scientists don’t know when the next reversal will occur.
“The Earth’s magnetic field reverses on average every 300,000 to 400,000 years,” explained Adrian Mogesworthy, professor of Earth and planetary magnetism at Imperial College London, who was not involved in the study. “But it is baffling. It is not typical. There are times when it doesn’t reverse for 30 million years, but we kind of do.
He said previous reverse geological records show that it can take 500 to 2,000 years for the Earth’s magnetic field to completely reverse, growing progressively weaker in the dominant direction and gradually strengthening in the opposite direction.
Although modern navigation systems such as the Global Positioning System (GPS) now rely on satellites in orbit, Muxworthy notes that satellites for navigation still rely on the geomagnetic field to align them.
He said that satellites in low orbits currently dictated by Earth’s magnetic field can be damaged by large amounts of solar radiation during field reversals, although they can be protected by making them heavier.
He said Earth’s magnetic field at its weakest would be 20 percent stronger than it is now, resulting in more solar radiation at the surface, though not enough to affect life there.
However, one intriguing side effect of changing the entire field is that the spectacular aurora borealis that now occurs mainly over the poles will occur all over the world.
It’s going to be really exciting,” Moxworthy said. “Just as we get the northern and southern lights now, we’ll see them at all latitudes, including the equator.”
Nelson warns that while his study of the South Atlantic anomaly suggests that they will disappear without a problem in a few hundred years, there is still a chance that Earth’s magnetic field will start to reverse anyway, although scientists haven’t seen any signs of that.
But, he said, “we certainly might be wrong.”
