In recent years, scientists have been gearing up for a potential flip in the magnetic field – a natural phenomena which occurs every 200,000 to 300,000 years when the north and south poles switch. The poles attempted to swap 40,000 years ago but the process failed. As a result, the last time the poles switched place was 780,000 years ago, meaning we are long overdue a flip in the magnetic field. Previous research had found that once the process of the pole reversal begins, it could take up to 1,000 years to complete.
However, a new study from the University of Wisconsin–Madison analysed lava flow sequences, ocean sediment dumping and Antarctic ice cores which were present prior to, during and post the last magnetic field reversal revealed that the switch could take up to 22,000 years to complete – putting previous estimates way off the mark.
Earth’s magnetic field is created by the liquid iron outer core spinning around the solid inner core.
The dynamic action creates an invisible field which goes through the north and south of the planet, and encircling it – hence where Earth gets the North and South Poles.
As new rocks form, usually though lava flows or ocean sediment being dumped, they record the magnetic field at the time, which is what the team of geologists used to date the last magnetic field reversal.
Geologist Brad Singer said: “Lava flows are ideal recorders of the magnetic field. They have a lot of iron-bearing minerals, and when they cool, they lock in the direction of the field.
“But it’s a spotty record. No volcanoes are erupting continuously. So we’re relying on careful field work to identify the right records.
“Reversals are generated in the deepest parts of the Earth’s interior, but the effects manifest themselves all the way through the Earth and especially at the Earth’s surface and in the atmosphere.
“Unless you have a complete, accurate and high-resolution record of what a field reversal really is like at the surface of the Earth, it’s difficult to even discuss what the mechanics of generating a reversal are.”
Other scientists have previously warned the pole reversal could leave Earth’s magnetic field will be compromised during the switching process, leaving living beings on the planet vulnerable to an increased dosage of radiation from the Sun.
Monika Korte, head of GFZ Potsdam’s working group on geomagnetic field evolution in Germany, told the website Space: “Regarding increased radiation, that would go along with decreased shielding, but it seems that the atmosphere would still provide sufficient shielding at Earth’s surface that humans and animals would not be significantly affected.
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“However, all the effects we currently only see during strong solar/geomagnetic storms would likely increase and occur during moderate solar activity.
“This includes satellite outages or damage to satellites, increased radiation doses on long-distance aircraft and the ISS (International Space Station), and distortions of telecommunication and GPS signals.”
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