This summer, the European Space Agency published data that suggested that the Earth’s magnetic field could flip — as in, the magnetic north pole becomes the magnetic south pole — in “a few thousand years.” At the time, I figured there was no rush to write it up — after all, we might not even be living on Earth in a few thousand years. Now, however, new research published this week shows that the magnetic field might flip within our lifetime — so it’s probably something that we ought to talk about.
The Earth’s magnetic field can flip…?
Earth’s magnetic north pole, vs. true/geographic north pole
As you probably remember from high school, the Earth is a giant bar magnet — a magnetic dipole with the north pole in the north, and the south pole in the south. If you imagine that there’s really a massive bar magnet in the middle of the Earth, it’s tilted by about 10 degrees from the planet’s axis, which is why the magnetic north pole — currently in the upper northern tracts of Canada — is a few hundred miles away from geographic/true north.
For now, magnetic north is close enough to true north that it doesn’t really matter (unless you’re trying to navigate using a compass in arctic or antarctic regions, in which case you’re in trouble). But the Earth’s magnetic field is shifting. New satellite data from the ESA shows that the Earth’s magnetic field is weakening 10 times faster than we previously thought — an indicator that scientists believe is a precursor to a geomagnetic reversal. At the time, there was nothing to worry about — previous geological records suggested that a geomagnetic reversal occurs over thousands of years. 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]
Earth’s various layers, including the crust, mantle, outer core, and inner core [Image credit: Kelvinsong]
What causes a geomagnetic reversal?
The Earth’s magnetic field is generated by the movement of molten iron in its outer core, through what’s known as the dynamo theory. We won’t know for sure until we actually get down there and do some investigating, but as far as scientific theories go it’s pretty well grounded.
Due to reasons we don’t fully understand, something causes the movement of the molten core to change — and thus the north and south poles switch. The most likely reason for the reversal is simply the general interaction and chaos of the massive dynamic forces at play — but there are some other hypothesized triggers, such as massive impacts, or significant plate tectonic shifts. The fact that there’s no evidence that a reversal occurred after the Cretaceous-Paleogene extinction event — the asteroid that wiped out the dinosaurs — suggests that impact events probably aren’t the cause, though.
In any case, these geomagnetic reversals occur irregularly, averaging around 450,000 years between each switch. The last reversal — the Matuyama-Brunhes reversal — occurred about 780,000 years ago, so it’s high time for another one to occur.
Are we all going to die horrible, fiery deaths?
At this point, scientists are pretty certain that a geomagnetic reversal is about to happen — they’re just not sure exactly when it will occur. Obviously, when you’re dealing with a mass of molten iron that is best measured in quintillions of tons, and your nearest seismological probes are thousands of miles away from the action, there’s a fair bit of guesswork involved.
If the ESA’s satellite data and the new paleomagnetic data (literally, the study of Earth’s magnetic fields by looking at rocks) are both accurate, then the Earth’s next geomagnetic reversal might have already begun. By the time we die — or at least when our children die — the north pole might be in the south.
NASA’s simulation of what Earth’s magnetic fields might look like during a geomagnetic reversal
Sadly, we can only guess at what actually happens to Earth — and all the lovely organisms that live on its surface — during a geomagnetic reversal. Most hypotheses and simulations suggest that there’ll be a fairly long period during the reversal where the poles are all messed up — so at the very least, you can forget using your compass to navigate. Organisms that use magnetoception to navigate — birds, bacteria, bees — might themselves similarly confused.
During this period, there won’t be a north or south pole at all, which might impact some computers and navigational systems – but in most cases, I would’ve thought software updates, plus GPS satellites, will have us covered.
There is also the possibility that our magnetic field will be significantly weakened during the reversal process, which would leave us — and more importantly, our atmosphere — vulnerable to the eroding effects of highly charged solar particles (solar wind). This possibility has led some scientists to suggest that a geomagnetic reversal would cause an extinction event — but so far, there are no fossil records that suggest that previous reversals were followed by mass extinctions. Likewise, considering many of the species currently on Earth lived through the last geomagnetic reversal, it would seem they already have some mechanism for coping with shifts in the magnetic field.
So, to answer the question: No, the impending geomagnetic reversal probably won’t cause some kind of apocalypse — but we may have to live through a few decades of pigeons getting lost, bacteria behaving weirdly, and other semi-serious problems. There is certainly a possibility that something nasty and world-ending will be triggered by a geomagnetic reversal — but we should have plenty of warning (months, years) if that’s the case.
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