Scientists in Japan Just Found a Detailed Record of Earth's Last Magnetic Switcharoo

 Every 200,000 to 300,000 years, Earth's magnetic poles reverse. What was once the North Pole becomes the south and the other way around. it is a time of invisible upheaval.

The last reversal was unusual because it absolutely was to see you later ago. for a few reasons, the poles have remained oriented the way they're now for about three-quarters of 1,000,000 years. a replacement study has revealed a number of the detail of that reversal.

The study of the Earth's magnetic flux is termed paleomagnetism. It involves the study of rocks and sediments and sometimes archaeological materials. Rocks that were once molten retain a record of the Earth's field of force as they solidified.

The related field of magnetostratigraphy studies the record of geomagnetic reversals that are contained in those rocks. By dating the rocks, researchers can construct a timeline of the Earth's reversals.

The last reversal is known as the Matuyama-Brunhes geomagnetic reversal after the co-discoverers: Bernard Brunhes, a French geophysicist, and Motonori Matuyama, a Japanese geophysicist. Over the years since its discovery, researchers have tried to grasp exactly when it happened, and also how long it took.

This new study is titled "A full sequence of the Matuyama–Brunhes geomagnetic reversal within the Chiba composite section, Central Japan." The lead author is Yuki Haneda, a project researcher at the National Institute of Polar Research and a postdoctoral research fellow at the National Institute of Advanced Industrial Science and Technology in Japan.

The paper is published in the journal Progress in Earth and Planetary Science.

Lava flows are a reliable indicator of the orientation of Earth's magnetic poles at the time the lava solidified. But what they cannot provide could be a timeline. They're more like snapshots that freeze a flash in time.

Lava flows are very helpful when it involves understanding the Earth's force field at the time of solidification. "However, lava sequences cannot provide continuous paleomagnetic records because of the character of sporadic eruptions," lead author Haneda said in very promulgation.

A better record will be found in some sediment deposits, which may form over an extended period of your time. one amongst these deposits is named the Chiba composite section. It's in Japan, and geophysicists consider it to be a really detailed record of the Matuyama-Brunhes reversal.

"In this study, we collected new samples and conducted paleo- and rock-magnetic analyses of samples from the Chiba composite section, never-ending and expanded marine succession in Central Japan, to reconstruct the complete sequence of the Matuyama-Brunhes geomagnetic reversal," Haneda said.

The Chiba composite section is widely considered to contain the foremost detailed marine sedimentary record of the Matuyama-Brunhes geomagnetic reversal, per Haneda.

It is the international standard for the lower boundary of the center Pleistocene Subseries and the Chibanian Stage — when a man emerged as a species.

The Chiba composite section is notable for its well-preserved pollen and marine micro- and macrofossils. It also contains tephra beds. Tephra could be a fragmentary material produced by volcanic eruptions, normally spoken as volcanic ash.

All in all, Chiba provides the foremost reliable chronostratigraphic framework of the fundamental measure round the Brunhes-Matuyama reversal.

What they found goes against what other studies have uncovered, especially when it involves how long the reversal took to occur. Some studies suggest it took several thousand years, while another suggested that the reversal was completed in one human lifetime.

The different time estimates depend largely on where on Earth researchers gather their evidence. This study supported the Chiba composite section says it took about 20,000 years, including a ten,000 year period of instability leading up to the reversal.

"Our data is one amongst the foremost detailed paleomagnetic record during the Matuyama-Brunhes geomagnetic reversal, offering deep insight into the mechanism of the geomagnetic reversal," Haneda said.

The marine micro-fossils and pollen found within the Chiba composite section also hold clues to the magnetic reversal. The team of researchers goes to analyze fossils and pollen next to undertake to find out more.

This figure from the study shows the location of the study area on Japan's Boso Peninsula. (Haneda et al., 2020)

The question that looms over Earth's geomagnetic reversals is 'What effect do they have?' That's outside the scope of this study, but it is the focus of other research. 

Some researchers have wondered if magnetic reversals have contributed to temperature change. While the evidence is nowhere near complete, some scientists have outlined how reversals might play a task.

In 2006 a team of researchers made a presentation to the American Geophysical Union's Fall Meeting titled "Does the Earth's force field Influence Climate?"

When mentioning the accepted causes of temperature change on Earth, the team said, "Magnetism has seldom been invoked, and evidence for connections between climate and force field variations have received little attention."

"The most intriguing feature is also recently proposed archaeomagnetic jerks. These seem to correlate with significant climatic events."

Archaeomagnetic jerks are quick changes within the Earth's geomagnetic field that are localized instead of global. While there's only a correlation between them and climate, a causal link might sooner or later be established. Could there even be a causal link between magnetic reversals and climate?

The effect that magnetic reversals wear animals is likewise a desirable and open question. Many animals undertake long, migratory voyages. Whales, birds, and sea turtles, for instance.

And there's evidence that some migratory species depend upon Earth's force field to navigate. The phenomenon is named magnetoreception.

How are creatures that depend upon magnetoreception suffering from geomagnetic reversals?

During a reversal, the magnetic poles not only switch places but the sphere strength drops. There might also be temporary poles at the equator or perhaps multiple temporary poles. The poles may also wander around, leaving their original position and returning before eventually switching completely.

It's not clear what effect a reversal has on animals. But there's some evidence that solar storms, with all their magnetic activity, can create confusion for migrating whales and will even drive them to beach themselves.

During a reversal, the protective effect of the Earth's field of force is reduced. More radiation may reach the surface of Earth during a reversal, which could put animals like whales in peril the identical way a solar storm might. However, the evidence for this can be not clear.

In any case, life on Earth has survived many geomagnetic reversals, and still, life thrives. Modern humans haven't faced one yet, so observing the following one are very instructive. 

The most likely effect is going to be on our power and communications systems, including satellites. because the global magnetic flux weakens, more of the Sun's radiation can get through. we all know from things just like the Carrington Event that that scenario is often very damaging. 

While this study can't address these questions, it does advance our understanding of the previous reversal. 

"Our results provide an in-depth and expanded sedimentary record of the M–B geomagnetic reversal and offer valuable new information to further understand the mechanisms and dynamics of geomagnetic reversals," the authors conclude.