Science

Earth's magnetic field could reverse in just one lifetime

Earth's magnetic field could r...
The direction of magnetic north suddenly reversed about 786,000 years ago, with new research indicating the switch occurred in under 100 years (Image: UC Berkeley)
The direction of magnetic north suddenly reversed about 786,000 years ago, with new research indicating the switch occurred in under 100 years (Image: UC Berkeley)
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The research team at an outcrop in the Sulmona basin of the Apennine Mountains where the magnetic records were located (Photo: Paul Renne/UC Berkeley)
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The research team at an outcrop in the Sulmona basin of the Apennine Mountains where the magnetic records were located (Photo: Paul Renne/UC Berkeley)
Two of the team collecting a sample for paleomagnetic analysis (Photo: UC Berkeley)
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Two of the team collecting a sample for paleomagnetic analysis (Photo: UC Berkeley)
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The direction of magnetic north suddenly reversed about 786,000 years ago, with new research indicating the switch occurred in under 100 years (Image: UC Berkeley)
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The direction of magnetic north suddenly reversed about 786,000 years ago, with new research indicating the switch occurred in under 100 years (Image: UC Berkeley)

A new study by a team of scientists from Italy, France, Columbia University and the University of California, Berkeley, demonstrates that the Earth's magnetic field could change polarity in less than 100 years. The last magnetic reversal occurred some 786,000 years ago and was previously thought to have taken several thousand years but, if the researchers are right, the real time it may take for the flip to occur could actually be closer to the span of a human life.

At the heart of the Earth is a solid inner core of iron with a temperature of around 5,700° C (10,200° F), and about two thirds of the size of the Moon. It is solid at this temperature because of immense gravitational force, however, it also has an outer layer about 2,000 km (1,240 mi) thick composed mainly of iron and nickel that is fluid. It is the flow and movement of this liquid iron that generates electric currents which, in turn, create magnetic fields.

Changes in temperature, the flow up and down of various metals, and reactions to centuries-long changes in composition densities are all theorized to be in some way responsible for the shift in the direction and intensity of this magnetic field.

The new research into this phenomenon is based on measurements taken of the magnetic field alignment of sedimentary layers in a prehistoric lake site in the Sulmona basin of the Apennine Mountains east of Rome, Italy, which show the change in magnetic alignment of material captured as sediment and frozen in time.

An Italian research team led by Leonardo Sagnotti of the National Institute of Geophysics and Volcanology measured the magnetic orientations contained in the sediments that amassed on the ancient lake bed and, because the lake sediments were laid down at a large and consistent rate over a 10,000-year period, the team was able to interpret the date of the layer containing the reversal of the magnetic field. Known as the Matuyama-Brunhes transition, this period occurred – according to the researcher’s dating tests – fairly close to 786,000 years ago.

When the ancient body of water existed, it was upwind from a province of high volcanic activity that included periodically erupting volcanoes near Sabatini, Vesuvius, and the Alban Hills. With ash layers distributed and interspersed on this former lake, the researchers were able to use argon-argon dating to determine the age of the ash layers situated above and below the layer of sediment that chronicled the last reversal. As a result, the date determined is far more precise than that of earlier studies, which had previously placed the reversal somewhere between 770,000 and 795,000 years ago.

According to the research, about 789,000 years ago the north magnetic pole started wandering around Antarctica. This lasted for several thousand years before suddenly reversing 786,000 years ago to roughly the point we know it in today in the Arctic.

"It’s amazing how rapidly we see that reversal," said UC Berkeley graduate student Courtney Sprain. "The paleomagnetic data are very well done. This is one of the best records we have so far of what happens during a reversal and how quickly these reversals can happen."

This new research comes at a time when fresh evidence points to the fact that the intensity of Earth's magnetic field is decreasing at a rate 10 times faster than expected, which has led some geophysicists to predict a reversal sometime within the next few thousand years. Though such a magnetic reversal would be a significant global event, there is no major evidence from geological and biological records that this was in any way catastrophic for life with past reversals.

Today, however, a reversal could theoretically wreak havoc with electrical grids from the collapse or change of electrical fields or – worse still – a period of indeterminate magnetic fields on the way to a full reversal may see cancer rates rise as radiation previously deflected by the Earth’s magnetic field may be allowed to bombard the planet.

"We should be thinking more about what the biologic effects would be," said Professor Paul Renne, director of the Berkeley Geochronology Center.

This is the most worrying aspect of the findings of this research, as the sudden 180-degree reversal of the magnetic field had a period of severe instability before it that lasted over 6,000 years with two intervals of about 2,000 years each that showed exceptionally low magnetic field strength. The complete magnetic polarity flip occurred somewhere near the end of the last of these low field strength intervals.

"What’s incredible is that you go from reverse polarity to a field that is normal with essentially nothing in between, which means it had to have happened very quickly, probably in less than 100 years," said Professor Renne. "We don’t know whether the next reversal will occur as suddenly as this one did, but we also don’t know that it won’t."

The results of the research will be published in the Geophysical Journal

Source: University of California Berkeley

12 comments
Mel Tisdale
It is not the fault of the article, which is very informative, that I am left wondering whether this is something I should be concerned about as far as my son and his family are concerned, or if I can safely leave it for those much further into the future to worry about. I assume, maybe somewhat rashly, that there is an international group, or groups, somewhere that is developing a plan of action should the poles suddenly begin a reversal. One thing I think we can be sure of is that in order to reduce being irradiated and the consequent cancer risks there will be migration away from any path that the poles might be seen to be following.
Wayne Day
I find myself falling back to a subject that I thought I was not interested in , of which I took when I had a professor that taught engineering and insisted we take his geology class ; go figure ? , although it's interesting .
Blazemonger
Why would the electrical grid be at risk. It is not like the permanent magnets that are used in generating power will change polarity. The electromagnetic fields from power generation and transmission are much stronger than the relatively weak magnetic field of the Earth.
OldGruff
@Blazemonger: I don't know that the Earth's magnetic poles have any effect on permanent magnets. However, my schooling tells me that a conductor experiencing a magnetic flux will produce a current. This is the principle behind most electrical power generators. So the electrical grid has a lot of conductors and movement of the Earth's magnetic poles would constitute a large magnetic flux. Depending on how quickly it happens, the grid could be overloaded with unexpected current.
Playability
The cause is obvious to someone like myself with no scientific qualifications and a lifetime's interest in quackery. The earth acts both as a gyroscope and as an electric motor. There is a solid core and a mantel which must have a unique magnetic pattern of mineral deposits, which tend towards a stable spin. When however as is happening now, there is an in-balance between the poles, the north disappearing and the South increasing massively, a force is being applied akin to making a gyroscope to precess. As the 'motor' is free to move in three dimensions rather than the two we are used to thanks to a fixed armature, given the right conditions the force may be enough to cause the relation between the core and the mantel to assume another symmetry - a 180 degree reversal, a flip which will be rapid and violent. The weather during such a phase should be horrendous! Then there will be calm!
Enlightened Wookie
even if the flux of the earth's magnetic field causes no problems for our electric grid or gadgets - what if we are hit with a nice solar flare during a time when the magnetic field is weak or almost non-existent. the previous comment about the weather makes me wonder if this is at all related to the currently perceived 'climate change'...
Bob
What effect will this have on iron deposits in the earth's crust? Stress, continental drift, a shift in the earth's axis or something else? Increased radiation, weather changes, ocean current shifts, creating another ice age? From various articles I have read, the earth probably has only another thousand years or so left, but that's another subject.
Gregg Eshelman
If Earth's magnetic field collapses or at least retreats below the surface for a time, all the solar and interstellar energy the field currently deflects toward the poles will be able to strike deeper into the atmosphere or even hit the surface.
Nairda
The concern is not so much that we can't adapt in some way to a reduced magnetic field, its more about how our biodiversity will be affected. Because it is one thing to have a higher rate of cancer and technology improving in this field to offset this (think 1000+ SPF sun cream, better cancer treatments, etc). But for the living creatures in the open that are already struggling from reduced habitat and pollution. There will definitely be a lot more extinctions. And I know some might claim that this is the cycle of nature, and the shift is a cyclic earth thing, but to me it seems like a cop out. If we can preserve a species just so that our next generation has one more thing to marvel at then all the better. Can think of no worse a future where the only living non-human creatures are those we grown for consumption.
nutcase
Any change in the magnetic properties of the earth's core must be governed by it's viscosity.