Earth’s magnetic field could flip within our lifetime
"Now, however, a new study has analyzed rocks from the previous flip — the Matuyama-Brunhes magnetic reversal of 786,000 years ago — and found that the process completed in under 100 years." [doi: 10.1093/gji/ggu287]
"Because of changing temperatures and fluid flows, the strength of the magnetic field varies, and the positions of the north and south magnetic poles shift.
These shifts leave traces in rocks. When lava cools, metal oxide particles within the rock become frozen in the direction of the prevailing magnetic field. So scientists can work out the historic positions of the magnetic poles by examining and dating lava samples.
As a result we know there have been about 170 magnetic pole reversals during the last 100 million years, and that the last major reversal was 781,000 years ago."
"Geophysicists have been studying the lava that has seeped up from the core and through a ridge on the floor of the Atlantic Ocean. As lava cools and solidifies, it preserves the direction of the Earth’s magnetic field so looking at the rock that has formed over time gives us an idea of what has happened to the magnetic poles in the past. These studies show that the poles switch ends every half million years or so – and that we’re due for another switch in the next few thousand years.
There’s also evidence to suggest that before the Earth’s magnetic poles switch, the magnetic field slowly fades out before reappearing with the poles reversed. And our magnetic field has depleted by 5% over the last century."
What Will Happen When the Earth’s Magnetic Field Begins to Reverse?
"With the sphere spinning at 45 miles per hour, and a little help from electromagnets, the team saw short-lived magnetic bursts within the sodium. When the spinning ramps up to nearly 90 miles per hour later this year, the sodium might generate a field without the extra nudge. If so, and with one second of the experiment equaling 5,000 years of Earth time, the researchers could see a reversal before everyone else on the planet."