A growing region of weak Earth’s magnetic field isn’t indicative of an impending pole shift, a new study shows.
Lund – A magnetic field protects the earth from the inhospitable and hostile environment of space. solar storms for example, the earth’s atmosphere would tear away if the geomagnetic field did not exist. But the earth’s magnetic field is not stable, and at irregular intervals – on average every 200,000 years – a so-called pole shift or pole reversal takes place. The magnetic north and magnetic south poles swap positions. The last pole shift took place about 780,000 years ago – and the signs that a polar reversal is imminent seem to be increasing.
In the past 180 years, the strength of the Earth’s magnetic field has decreased by around ten percent, and since the 1990s the North Pole has been moving at around 55 kilometers a year – three times faster than before. At the same time, a region with an unusually weak magnetic field is growing in the South Atlantic. This area off the coast of Brazil is called the “South Atlantic Anomaly” and it’s growing. Some experts interpret this as a sign of the upcoming pole shift – but in a new study, researchers have now come to the conclusion that the earth is unlikely to face a pole reversal after all.
Earth is not facing a pole shift: researchers give the all-clear
For their study, researchers led by geologist Andreas Nilsson from Lund University in Sweden examined archaeological finds, volcanic deposits and deep-sea sediments for information about the Earth’s magnetic field. The objects – including clay pots and solidified volcanic lava – are like time capsules and carry information about the earth’s magnetic field of the past, according to one Communication from Lund University. Using sensitive instruments, researchers can reconstruct the direction and strength of the magnetic field at specific locations and times.
“We have mapped the changes in the Earth’s magnetic field over the past 9,000 years,” explains Nilsson. “Anomalies like those in the South Atlantic are likely to be recurring phenomena associated with corresponding fluctuations in the strength of the Earth’s magnetic field.” A new modeling technique was developed for this purpose, which uses indirect observations from different time periods and locations to form a global reconstruction of the magnetic field over the past 9000 years summarizes, says Nilsson. The study was published in the journal Proceedings of the National Academy of Sciences.
Earth’s Magnetic Field Researched: “Earth Is Not Heading For Polarity Reversal”
The researchers not only found out a lot about the Earth’s magnetic field, but also about the underlying processes that take place in the Earth’s core and create the magnetic field. The new model can be used to date archaeological and geological objects, but it also gave the researchers a reassuring insight: “Based on the similarities to the anomalies being replicated, we predict that the South Atlantic Anomaly is likely to disappear within the next 300 years and that the earth is not heading for a pole shift,” summarizes Andreas Nilsson.
The result of the study by Nilsson and his research team is particularly reassuring because a pole shift could have serious consequences for the earth. Experts assume that the earth’s magnetic field will almost disappear for several centuries if the poles are reversed. This could have devastating effects on the Earth’s climate and technology on Earth and in orbit could also have problems because they would be fully exposed to the solar wind. (tab)
Earth’s last pole shift
While the last pole reversal occurred 780,000 years ago, more recently – around 42,000 years ago – there was what is known as a polarity excursion. The geometry of the earth’s magnetic field changes for several hundred years. The brief reversal of the earth’s magnetic field lasted about 440 years, the reversal of polarity and the return to the “old” polarity each lasted about 250 years. The reversed magnetic field reached only a quarter of the strength of the normal earth’s magnetic field.
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