Our Planet’s Magnetic Fields to Flip – Should We Be Flipping Out?
Earth’s magnetic field acts as a sort of invisible shield, deflecting otherwise lethal radiation. This force field is constantly changing as has hundreds of times in our planet’s history but what would happen to life on Earth the next time this global event occurs?
The major issue with a magnetic pole flip would be that the strength of this field could drop to as low as ten percent of what it is currently at. Geomagnetic reversals typically occur a few times every million years on average.
There can also be temporary and incomplete reversals, known as events and excursions, in which the magnetic poles move away from the geographic poles – perhaps even crossing the equator – before returning back to their original locations. A temporary reversal, the Laschamp event, occurred around 41,000 years ago. It lasted less than 1,000 years with the actual change of polarity lasting around 250 years.
The last full reversal, the Brunhes-Matuyama, occurred around 780,000 years ago, putting us well within range of the 1,000,000 year average interval. Fortunately, full polar shifts can have intervals as long as 10,000,000 years.
Power Cut or Mass Exctinction?
The alteration in the magnetic field during a reversal will weaken its shielding effect, allowing heightened levels of radiation on and above Earth’s surface. Were this to happen today, the increase in charged particles reaching Earth would result in increased risks for satellites, aviation, and ground-based electrical infrastructure.
Geomagnetic storms, driven by the interaction of anomalously large eruptions of solar energy with our magnetic field, give us a foretaste of what we can expect with a weakened magnetic shield.
In 2003 a geomagnetic storm hit our magnetic field above Sweden, disrupting satellites and causing severe electrical blackouts. Airline flights had to be rerouted to avoid a communication blackout and potential harm of radiation. But this storm was minor in comparison with other storms of the recent past, such as the 1859 Carrington event, which caused aurorae as far south as the Caribbean.
If this were to happen at a much larger scale it could mean our the dropping of our communications grid and most of our electrical applications. Such an event could be catastrophic for humanity.
In terms of life on Earth and the direct impact of a reversal on our species we cannot definitively predict what will happen as modern humans did not exist at the time of the last full reversal. Several studies have tried to link past reversals with mass extinctions – suggesting some reversals and episodes of extended volcanism could be driven by a common cause.
We do know that many animal species have some form of magnetoreception that enables them to sense Earth’s magnetic field. They may use this to assist in long-distance navigation during migration. But it is unclear what impact a reversal might have on such species.
What is clear is that early humans did manage to live through the Laschamp event and life itself has survived the hundreds of full reversals evidenced in the geologic record.
Can We Predict the Next Full Reversal?
In short, no. We do know that our magnetic field is currently decreasing at a rate of about five percent per century, so experts have taken an educated guess that it may be within the next 2,000 years but an exact date is nearly impossible at this point.
Earth’s magnetic field is generated within the liquid core of our planet, by the slow churning of molten iron. Like the atmosphere and oceans, the way in which it moves is governed by the laws of physics. We should therefore be able to predict the ‘weather of the core’ by tracking this movement, just like we can predict real weather by looking at the atmosphere and ocean.
Fully observing this weather is difficult considering there is over 3,000 kilometers of rock in the way. However, we have a global network of ground-based observatories and orbiting satellites constantly measuring how the magnetic field is changing, which gives us insight into how the liquid core is moving.
The recent discovery of a jet-stream within the core highlights our evolving ingenuity and increasing ability to measure and infer the dynamics of the core. Coupled with numerical simulations and laboratory experiments to study the fluid dynamics of the planet’s interior, our understanding is developing at a rapid rate.
The prospect of being able to forecast Earth’s core is perhaps not too far out of reach…
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