Earth's magnetic field could flip within a human lifetime

October 14, 2014, University of California - Berkeley
Earth's magnetic field could flip within a human lifetime
The ‘north pole’ — that is, the direction of magnetic north — was reversed a million years ago. This map shows how, starting about 789,000 years ago, the north pole wandered around Antarctica for several thousand years before flipping 786,000 years ago to the orientation we know today, with the pole somewhere in the Arctic. Credit: University of California - Berkeley

Imagine the world waking up one morning to discover that all compasses pointed south instead of north.

It's not as bizarre as it sounds. Earth's has flipped – though not overnight – many times throughout the planet's history. Its dipole magnetic field, like that of a bar magnet, remains about the same intensity for thousands to millions of years, but for incompletely known reasons it occasionally weakens and, presumably over a few thousand years, reverses direction.

Now, a new study by a team of scientists from Italy, France, Columbia University and the University of California, Berkeley, demonstrates that the last magnetic reversal 786,000 years ago actually happened very quickly, in less than 100 years – roughly a human lifetime.

"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."

Sprain and Paul Renne, director of the Berkeley Geochronology Center and a UC Berkeley professor-in- residence of earth and planetary science, are coauthors of the study, which will be published in the November issue of Geophysical Journal International .

Flip could affect electrical grid, cancer rates

The discovery comes as new evidence indicates that the intensity of Earth's magnetic field is decreasing 10 times faster than normal, leading some geophysicists to predict a reversal within a few thousand years.

Though a magnetic reversal is a major planet-wide event driven by convection in Earth's iron core, there are no documented catastrophes associated with past reversals, despite much searching in the geologic and biologic record. Today, however, such a reversal could potentially wreak havoc with our electrical grid, generating currents that might take it down.

And since Earth's magnetic field protects life from energetic particles from the sun and cosmic rays, both of which can cause genetic mutations, a weakening or temporary loss of the field before a permanent reversal could increase cancer rates. The danger to life would be even greater if flips were preceded by long periods of unstable magnetic behavior.

"We should be thinking more about what the biologic effects would be," Renne said.

Dating ash deposits from windward volcanoes

The new finding is based on measurements of the magnetic field alignment in layers of ancient lake sediments now exposed in the Sulmona basin of the Apennine Mountains east of Rome, Italy. The lake sediments are interbedded with ash layers erupted from the Roman volcanic province, a large area of volcanoes upwind of the former lake that includes periodically erupting volcanoes near Sabatini, Vesuvius and the Alban Hills. Italian researchers led by Leonardo Sagnotti of Rome's National Institute of Geophysics and Volcanology measured the magnetic field directions frozen into the sediments as they accumulated at the bottom of the ancient lake.

Sprain and Renne used argon-argon dating, a method widely used to determine the ages of rocks, whether they're thousands or billions of years old, to determine the age of ash layers above and below the sediment layer recording the last reversal. These dates were confirmed by their colleague and former UC Berkeley postdoctoral fellow Sebastien Nomade of the Laboratory of Environmental and Climate Sciences in Gif-Sur-Yvette, France.

Because the were deposited at a high and steady rate over a 10,000-year period, the team was able to interpolate the date of the layer showing the , called the Matuyama-Brunhes transition, at approximately 786,000 years ago. This date is far more precise than that from previous studies, which placed the reversal between 770,000 and 795,000 years ago.

"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 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."

Unstable magnetic field preceded 180-degree flip

Whether or not the new finding spells trouble for modern civilization, it likely will help researchers understand how and why Earth's magnetic field episodically reverses polarity, Renne said.

The magnetic record the Italian-led team obtained shows that the sudden 180-degree flip of the field was preceded by a period of instability that spanned more than 6,000 years. The instability included two intervals of low magnetic field strength that lasted about 2,000 years each. Rapid changes in field orientations may have occurred within the first interval of low strength. The full magnetic polarity reversal – that is, the final and very rapid flip to what the field is today – happened toward the end of the most recent interval of low field strength.

Renne is continuing his collaboration with the Italian-French team to correlate the lake record with past climate change.

Explore further: Tracking a Jurassic reversal of the Earth's magnetic field

More information: Geophys. J. Int. (November, 2014) 199 (2): 1110-1124. DOI: 10.1093/gji/ggu287

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5 / 5 (9) Oct 14, 2014
How would a reversal effect birds, fish and other life forms that use Earth's magnetic field for navigation? Could this cause an extinction for a species? (I'm specifically speaking about travelling north instead of south for the winter(ie birds), then freezing to death...)
4.3 / 5 (7) Oct 14, 2014
Good question. Maybe a geophysicist will drop by?

My thought on something else: During the period of instability there might be more than two "poles" at any given time, that migrate, merge (like sunspots) or simply disappear.

Maybe a biologist will drop by, as well?
3 / 5 (6) Oct 14, 2014
How would a reversal effect birds, fish and other life forms that use Earth's magnetic field for navigation? Could this cause an extinction for a species? (I'm specifically speaking about travelling north instead of south for the winter(ie birds), then freezing to death...)

i dunno. i have to say that almost all species have gone through it before and no one has notices a mass die off or anything like that.
4.4 / 5 (7) Oct 14, 2014
This may not just affect birds and such; read on:

Stephen Juan, an anthropologist from the University of Sydney, wrote that Caltech scientists discovered that humans possess crystals of magnetite in the ethmoid bone, just behind the nose:

Magnetite helps orientation and direction finding in animals. It no doubtingly helps migratory species migrate successfully by allowing them to draw upon the earth's magnetic fields. In the case, when it comes to humans, magnetite makes the ethmoid bone sensitive to the earth's magnetic field and helps one's sense of direction. Some have even suggested that this "compass" was helpful in human evolution as it made migration and hunting easier.
1 / 5 (22) Oct 14, 2014
It is all the fault of climate change caused by man. to cold, to hot, south instead of north, no rain, to much rain, wind blows, wind does not blow, all mans fault. If you want to stop the reversal of the north and south poles, send your money to Al Gore and company and all will be okay in gods eye. As to the fish and birds etc who use the magnetic field, they have all gone through this before so have a cup of coffee and a donut and relax.
1.3 / 5 (14) Oct 15, 2014
There is nothing to say that a magnet would flip at the same speed every time it rotates. They may be close on the last flip by studying rocks but there is way to many variables that are not the same as the last time it flipped. The land masses are different, the moon is not the same distance...etc etc
The more I read this website the more I find that science is way to narrow minded. People study there field of expertise and come to conclusions but don't take other fields into consideration.
4.8 / 5 (16) Oct 15, 2014
The more I read this website the more I find that science is way to narrow minded. People study there field of expertise and come to conclusions but don't take other fields into consideration.

The extent of your ability to compose a grammatically correct comment leaves the rest of us with a hint as to the value of your thoughts.
5 / 5 (7) Oct 15, 2014
Sometimes a lucky find yield a lot of data.

@lkdjfsd: Good questions!

"How would a reversal effect birds, fish and other life forms that use Earth's magnetic field for navigation?" It would be insignificant on the large scale, seeing how this has happened hundreds or thousands of times under the 500 million year of arthropods, fishes et cetera.

"Could this cause an extinction for a species?" It could according to Murphy's law. But the average risk is likely low. (E.g. "there are no documented catastrophes associated with past reversals".)
5 / 5 (14) Oct 15, 2014
Currents generated are proportional to rate and magnitude of field change, and the geomagnetic field is vanishingly small.

The danger lies more in the larger impact of solar storms due to the lack of shielding during the interval of almost vanished geomagnetic field.
5 / 5 (5) Oct 15, 2014
The instability included two intervals of low magnetic field strength that lasted about 2,000 years each. Rapid changes in field orientations may have occurred within the first interval of low strength.

This could cause problems for satellites in low earth orbit.

1.6 / 5 (14) Oct 15, 2014
"The extent of your ability to compose a grammatically correct comment leaves the rest of us with a hint as to the value of your thoughts."

To insult your fellow poster is a more accurate measurement of intellect & character than grammatical inconsistencies.

So can quoting correctly???

1.3 / 5 (3) Oct 15, 2014
If it last happened 780,000 years ago and takes hundreds of years in process, there is no way we have history to predict the impact on species.
4.2 / 5 (5) Oct 15, 2014
. . .
It's funny how complicated theories (usually based on math) neglect the physical realities which discount them. As do the supporters of said theories.

Pardon our complexities for getting in the way of your facile understanding.
1 / 5 (16) Oct 15, 2014
What a load of TWADDLE! The Earth's magnetic orientation has SHIFTED, it has NOT "flipped", SEVEN TIMES in historic times! These "shifts" WERE CAUSED by EXTERNAL FORCES--a "comet" that later became the planet Venus, nearly COLLIDED with Earth, ca 1500 BCE, and returned on a period of approximately 52 years, until ca 687 BCE, when it dislodged the planet Mars, which THEN threatened Earth for a brief period, during the Golden Age of Greece, and the rise of the Roman Empire, who adopted the red planet as their "god". In Homer's Illiad, we find a record of the near-collision, in the battle between Athena, then the dominant god of the Ancient World, and Ares, whom the Roman named Mars, witnessed by Earth-bound observers. There are records in the Old Testament, as well, of the near-misses of Venus and Earth, that have been co-opted for purposes of reinforcing a "recrimant God" of the OT. If you set aside the superstition, and the glib hipness of being 21st Century too-hipsters . . . TBC
1 / 5 (16) Oct 15, 2014
. . .it is easy to see an attempt by a non-scientific culture to pass down the generations, a message of a time when the Solar System was much more dangerous, and far less predictable, as main-stream cosmologists would have it today. This idea of the Earth SUDDENLY, and without valid reason, BUT to conform to records that CANNOT be denied, "flipped" over, is hogwash, and a blatant disregard for cross-discipline evidence. To start, Earth and Venus are NEARLY the same size--<200 miles difference--while Mars is only 52% of the size of Earth. The differences in Volume and Mass tell an even greater disparity: Venus is more than 80% of Earth's Volume and Mass, while puny Mars is barely 15% of Earth's Volume and little more than 11% of Earth's Mass. It's not unreasonable to expect a body almost the size of Earth to have PROFOUND effects in a NEAR-MISS flyby, as are told, in Exodus. Similarly, the battle witnessed by the residents of Troy, some 800 years later, are a dramatic . . . TBC
1 / 5 (15) Oct 15, 2014
. . . depiction of what such a near-collision might well have appeared as. Given the confusion in dating the Ancient World, thanks in no small part to the lack of cross-discipline scientific communication, it's no small wonder that we would look at Homer's tale as wondrous and mystical. However, given the following story, in the Odyssey, when Jason is unable to sail back to his home country, across a small sea the Greeks had been traversing for centuries, it stands to reason, that SOMETHING happened, to CHANGE the landscape, the topography, the maps! A similar story is told in Exodus, as the Jews, the escaped slaves, "Wandered in the Wilderness, for 40 years". Theologists would have you believe this was a "punishment from God", but what if the world NO LONGER looked as it had, only a short time before. The Bible speaks of the landscape melting, and other records agree, from near and far sources, leading one to speculate that the REASON the Jews could NOT find their way "home" . .
1 / 5 (14) Oct 15, 2014
. . . had FAR MORE to do with the UPLIFTING of mountains and volcanoes, which erupted constantly, setting the surrounding areas afire, as we know them to do do. Consequently, the world the Jews HAD known was GONE, forever. Similarly, in the wake of "Athena's" (Venus') attack on Troy, according to those who THOUGHT that was "her" aim, anyway, it's easy to understand HOW the inland sea the Greeks HAD known so well, and also helps to explain the decline of Ancient Greece, allowing the Romans to walk in and take over, a few centuries later. These things happened, and there are many, many more records demonstrating their veractiy. Unfortunately, TOO MANY "scientists' have been INFECTED with this kind of nonsense, and seek answers that "explain" the visible record, WITHOUT thinking in a linear fashion, FROM the records, to a theory! It's time to RECLAIM our past, and STOP this intellectual dishonesty!
5 / 5 (11) Oct 15, 2014
Uh, if Mars or Venus had gone 'walkabout', then Mercury and the asteroid belt would not have such tidy orbits. Besides, even with solar tides to slowly soak up angular momentum etc, neither planet would have settled down yet.

Spouting a version of Velikovsky's notions without checking the cruel math is no better than fantasy.
4.6 / 5 (11) Oct 15, 2014
joined October 15, 2014, 1:11 pm
immediately ranted obvious BS designed to elicit a response.

Downvote and ignore...
1 / 5 (8) Oct 16, 2014
is it possible that the sun would rise from the West !!
5 / 5 (4) Oct 16, 2014
is it possible that the sun would rise from the West !!

No, that would require the earth's rotation to change, which is absolutely not what we're talking about here (it would require a massive amount of energy to do so, nothing near what the reversal of polarity of the magnetic field could provide, even if you were to design a mechanism to do so).
4.8 / 5 (4) Oct 16, 2014

Another instant troll created at October 16, 2014, 11:05 am
Downvote and ignore...
not rated yet Oct 20, 2014
A little late to the party, but the reversal of convection in the geo-dynamo can be likened to the reversal of convection in the Lorenz atmospheric model (in fact, some geo-dynamo models are mathematically similar to the Lorenz model--they're both heated fluids).
not rated yet Oct 20, 2014
The instabilities in pre-turbulent flow (non-linear interaction) make it possible. A fluid heated sufficiently will convect, and those currents tend to form cells with definite directions of circulation (Rayleigh-Bernard). If heated still further the direction of convection in those cells can change spontaneously and repeatedly at irregular intervals (chaos). This is well established fluid dynamics. Simple geo-dynamo models accounts for this fluid behavior plus the magnetic field (both generating and responding to it). Reversals are not triggered by external events, but by internal instabilities. These models predict chaotic field reversals, which makes them quite plausible based on observations.
1 / 5 (2) Oct 20, 2014
lkdjfsd : If the poles flipped quickly would the birds fly in the correct direct direction when the seasons changed?

Most would die. Some might survive if the stars were visible at night. Some might correct the misleading magnetic directions.
However, remember the news stories of birds migrating in the wrong direction and arriving in the snow instead of the warm sandy beaches. It is normal for a few birds to migrate in the wrong direction, which will save their lives. I have almost no hope that the reverse direction migration is inherited.
1 / 5 (3) Oct 20, 2014
Torbjorn_Larsson_OM: "there are no documented catastrophes associated with past reversals".
Hilarious if you mean carved tablets or cave paintings. From Paleontology, not mass extinctions, but generation of new species within a genii.

Current models point to a multi-pole state during the flip. Lava in Oregon shows that the local magnetic field can undergo 180 degree flips in four hours. (Did I also see that on Nova or Discovery Channel years ago?)
1 / 5 (2) Oct 20, 2014
mohanadwaswas: (After the magnetic pole changes,) could the sun rise in the west?

If the local magnetic multipole sets up that way, then the sun could be said to rise in the magnetic West, or after a full pole shift. However, I believe that may be selling the prophesy short, refereed papers have been published analyzing evidence that the surface of Mars released from the underlying core and shifted significantly. The only thing that I can think of that would release the surface of the Earth is Mother Shipton's prophesies. In particular, the tidal forces on the Earth from a passing Earth mass planet could break the large subducting plates and reduce the bond between the lithosphere and the underlying, low viscosity layers.
not rated yet Oct 21, 2014
I imagine a 90 degree shift would cause some issues.
not rated yet Oct 22, 2014
It doesn't have to be heated further. It just has to be hot enough to lie within the chaotic regime. The simple models follow the average circulation (basically a Fourier mode), and doesn't spatially resolve it, but there are more detailed MHD models that do spatially resolve the core (http://www.nature...3a0.html & http://www.psc.ed...r.html). Energy is constantly changing form in such an environment--I'm guessing that during a reversal some of the bulk kinetic energy gets bound up in heat and then released back into kinetic as the reversal completes.

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