New Geological Evidence Suggests Earth's Magnetic Poles Could Flip at Any Time

Thursday, 23 August 2018 - 11:46AM
Physics
Earth
Thursday, 23 August 2018 - 11:46AM
New Geological Evidence Suggests Earth's Magnetic Poles Could Flip at Any Time
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Image Credit: MSFC
For the past few years, scientists have waffled between warning that the Earth's magnetic poles could flip at any time (with disastrous consequences) and assuring the public that everything's fine. Either way, the South Atlantic Anomaly (a shifting 'hole' in Earth's magnetic field) is still growing, and Earth's overall magnetic field continues to weaken. Previously, it was thought that the lead-up to a pole reversal (and the switch back to 'normal') would take thousands of years, but scientists investigating a cave in the Guizhou Province of China have found further evidence that the Earth's magnetic field can flip back and forth relatively quickly—over the course of just a century.

The last major pole reversal happened about 780,000 years ago and a second, minor one occurred about 41,000 years ago, which gives scientists a potential benchmark of how often these kinds of magnetic flips can happen. In the meantime, the poles have done a good amount of wandering during 'excursions,' periods where the poles drift around the Earth slightly. These changes are hard to predict, but we do know that they're caused by activity within the Earth, specifically having to do with the planet's iron core: the outer core has a lot of liquid metal flowing around it, which creates electrical currents, and the spin of the Earth shapes these currents into a kind of warped bubble of magnetism that surrounds the Earth. The major problem with a pole reversal is that the Earth's magnetic field may become significantly weaker, which means the planet will be vulnerable to solar radiation that can cause havoc for our electronic devices.

One of the things scientists have taken for granted is that the process of a pole reversal would be very slow and gradual, allowing us to deal with the problem before it became cataclysmic. However, a stalagmite found in the aforementioned cave in China shows that pole reversals can happen relatively quickly. The rock itself is composed partly of magnetite, which can become magnetized by the planet's magnetic field, allowing geologists to use it as a record of Earth's magnetic history. According to the geological 'records' held within this stalagmite, there was a very sudden magnetic reversal 98,000 years ago that only lasted about a hundred years.

Though a pole reversal might not be the next Y2K, a sudden flip in the Earth's magnetic field could be disastrous if we're not prepared. Unfortunately for us, no one can see for certain when or if one will occur—all we can do is watch the signs.

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