Earth's magnetic field is not about to reverse, study finds

Earth's magnetic field is not about to reverse
Intensity at Earth's surface (left) and radial field (Br) at the CMB (right). Top: mid-point of the Laschamp excursion; bottom: mid-point of the Mono Lake excursion. Thefield is truncated at spherical harmonic degree five. Credit: University of Liverpool

A study of the most recent near-reversals of the Earth's magnetic field by an international team of researchers, including the University of Liverpool, has found it is unlikely that such an event will take place anytime soon.

There has been speculation that the Earth's may be about to reverse , with substantial implications, due to a weakening of the over at least the last two hundred years, combined with the expansion of an identified weak area in the Earth's magnetic field called the South Atlantic Anomaly, which stretches from Chile to Zimbabwe.

In a paper published in the Proceedings of the National Academy of Sciences, a team of international researchers model observations of the geomagnetic field of the two most recent geomagnetic excursion events, the Laschamp, approximately 41,000 years ago, and Mono Lake, around 34,000 years ago, where the field came close to reversing but recovered its original structure.

The model reveals a field structures comparable to the current geomagnetic field at both approximately 49,000 and 46,000 years ago, with an intensity structure similar to, but much stronger than, today's South Atlantic Anomaly (SAA); their timing and severity is confirmed by records of cosmogenic nuclides. However, neither of these SAA-like fields developed into an excursion or reversal.

Richard Holme, Professor of Geomagnetism at the University of Liverpool, said: "There has been speculation that we are about to experience a magnetic polar reversal or excursion. However, by studying the two most recent excursion events, we show that neither bear resemblance to current changes in the geomagnetic field and therefore it is probably unlikely that such an event is about to happen.

"Our research suggests instead that the current weakened field will recover without such an extreme event, and therefore is unlikely to reverse."

The South Atlantic Anomaly is probably not an evidence of a reversing Earth's magnetic field
Increased occurrence of radiation-induced technical satellite failures of the Swarm satellites (white spots) in the region of the geomagnetic South Atlantic Anomaly (blue color = reduced field intensity) between April 2014 and June 2017. Credit: I. Michaelis, GFZ

The strength and structure of the Earth's magnetic field has varied at different times throughout geological history. At certain periods, the geomagnetic field has weakened to such an extent that it was able to swap the positions of magnetic north and magnetic south, whilst geographic north and geographic south remain the same.

Called a geomagnetic reversal, the last time this happened was 780,000 years ago. However, geomagnetic excursions, where the field comes close to reversing but recovers its original , have occurred more recently.

The South Atlantic Anomaly is probably not an evidence of a reversing Earth's magnetic field
The strength of the geomagnetic field at Earth's surface three times during the past: 48,500 and 47,250 thousand years ago and in 2015. The geomagnetic field of the past showed areas of weak intensity similar to today's South Atlantic Anomaly over South America and the southern Atlantic, for example 48,000 years ago. The anomaly of that time did, however, not lead to a geomagnetic field reversal, about one thousand years later the field recovered to a stable state of field strength. Credit: M. Korte/GFZ

The magnetic field shields the Earth from solar winds and harmful cosmic radiation. It also aids in human navigation, animal migrations and protects telecommunication and satellite systems. It is generated deep within the Earth in a fluid outer core of iron, nickel and other metals that creates electric currents, which in turn produce magnetic fields.


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More information: Maxwell Brown el al., "Earth's magnetic field is probably not reversing," PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1722110115
Citation: Earth's magnetic field is not about to reverse, study finds (2018, April 30) retrieved 20 August 2019 from https://phys.org/news/2018-04-earth-magnetic-field-reverse.html
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Apr 30, 2018
Sure it is.

Hey happy Walpurgisnacht everybody - the most happiest time of the year!

Apr 30, 2018
Phrases "about to", "not about to", "not anytime soon" are highly relative, increase scientific fluff.

Apr 30, 2018
Oh come on guys is it or isn't it? You got the X-Men mutants not knowing whether to change their suits or not! Ha!

May 01, 2018
We don't even know what causes the reversal!

May 01, 2018
The powers of our magnetic field, Walpurgisnacht and an English nun became a witch

Early in Germany's history, people celebrated the coming of Spring. The end of a long winter meant the end of hunger, and a chance for new life. According to tradition to help usher in the new season, all the Witches and Warlocks would fly in from all around Germany on Broomsticks and come together on the Broken on April 30th. This highest peak of the Harz Mountains was the meeting place for Walpurgisnacht, to celebrate and to await the arrival of Spring with bonfires and dancing.

Pity we cannot tap into Earth's inexhaustible supply of magnetism http://germangirl...isnacht/

TheGhostofOtto1923 - Sure it is. Hey happy Walpurgisnacht everybody - the most happiest time of the year!


May 01, 2018
Early in Germany's history, people celebrated the coming of Spring. The end of a long winter meant the end of hunger, and a chance for new life. According to tradition to help usher in the new season
Actually, pagan fertility rituals are cultural precursors to our biological transition from a tropical to a temperate species.

The farther north a species resides, the more seasonal it's breeding becomes. Offspring have the best chance of surviving the coming winter when born in the spring. For humans this means mating at the end of winter, and early tribes celebrated and encouraged this practice with rites and rituals. This also explains the tradition of the June wedding.

Xianity vilified this practice because it reduced growth and restricted their ability to outgrow and overwhelm. Midwives who taught abortion and birth control were deemed witches and burned.
Cont>

May 01, 2018
Like tribalism itself, had this practice gone on long enough we would have become biological seasonal breeders. The appropriate genes must already reside within us as they emerge again and again any time a species finds itself living in cold climes.

In Dan Brown's book Inferno, the main antagonist concocts a virus that sterilizes 1/3 the worlds population, in order to reduce growth. How much better off would we be as a species if we were preoccupied with reproduction for only one month a year?

Reduced growth would eliminate war. The sexes would have a genuine chance of equality. Of course most fashion and the performing arts would disappear because they largely involve tempting the other sex and posturing about who is worthy of repro rights.

We might even see social institutions based on competition like capitalism, democracy, and intercollegiate sports, disappear. And of course religion, which depends entirely on maximizing our tropical repro rate for survival.

May 01, 2018
Brave New World.

Anybody got a CRISPR and a glove box they aren't using? The snows gone, the suns out, otto feels like saving humanity today.

May 01, 2018
good luck with that otto.

Though I suspect a decided lack of gratitude for your efforts from the people you save.

"The difference between a Man and a Dog is, a dog will show gratitude when you feed it."

May 01, 2018
Like tribalism itself, had this practice gone on long enough we would have become biological seasonal breeders. The appropriate genes must already reside within us as they emerge again and again any time a species finds itself living in cold climes.

In Dan Brown's book Inferno, the main antagonist concocts a virus that sterilizes 1/3 the worlds population, in order to reduce growth. How much better off would we be as a species if we were preoccupied with reproduction for only one month a year?

So am I to assume that a magnetic field reversal will enhance reproductive activities via mass power cuts and people having nothing else o do? Or do you mean the opposite...Ha!

May 02, 2018
So am I to assume that a magnetic field reversal will enhance reproductive activities via mass power cuts and people having nothing else o do? Or do you mean the opposite...Ha!
Maybe But geese will fly north in the fall which will screw everything up.

May 02, 2018
Oh and BTW Venus didn't emerge from Saturn. Certainly not fifty million years ago.

Just sayin'.

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