The most Interesting discoveries about the Earth in recent decades relate to the Earth’s magnetic poles. Paleomagnetic records show that the poles have flipped 183 times in the last 83 million years. This occurs every 450,000 years on average, although in at least two cases there were tens of millions of years between flips.
Earth’s magnetic field is currently undergoing some rapid changes, but scientists say this has nothing to do with the movement of the poles.
When the poles reverse, scientists call it a geomagnetic reversal, and the last one happened about 780,000 years ago. It takes 2,000 to 7,000 years for the poles to reverse. The proof lies in the magnetic minerals inside the rocks. Magnetic minerals record the strength and direction of the Earth’s magnetic fields when they are enclosed in either sediment or magma. The study of magnetism in the primary rocks of the earth is called paleomagnetism.
There is currently a region in the South Atlantic where the Earth’s magnetic field is rapidly weakening. This is dubbed the South Atlantic Anomaly (SAA) and raises questions about its role in the geomagnetic reversal, if any.
The Earth’s magnetic field. Shutterstock
Scientists have known about SAA for some time. They weren’t sure if the anomaly indicated an upcoming geomagnetic reversal. Researchers behind a new study examined evidence going back thousands of years to determine if SAA heralded an impending reversal.
In the last 180 years, the strength of the earth’s magnetic field has decreased by about 10 percent. At the same time, the size of the SAA has grown. Scientists have speculated that these events could be related to geomagnetic reversals.
a new study in Proceedings of the National Academy of Science discovered a connection between SAA, decreasing field strength and geomagnetic reversal. It is entitled “Recurrent anomalies of old geomagnetic fields shed light on the future development of the South Atlantic anomaly”. The lead author is geologist Andreas Nilsson from Lund University in Sweden.
“We have mapped changes in the Earth’s magnetic field over the past 9,000 years, and the anomalies in the South Atlantic are likely recurring events associated with corresponding fluctuations in the strength of the Earth’s magnetic field,” Nilsson said in a press release.
Researchers examined three types of evidence: solid volcanic samples, sediment cores, and burned archaeological artifacts. Artifacts such as ceramics heated to over 580 degrees Celsius (1076 F) allow magnetic materials to reorient themselves in the Earth’s magnetic field at this point. All three types of evidence serve as time capsules, capturing a snapshot of Earth’s magnetism at a specific point in time.
“We have developed a new modeling technique that combines these indirect observations from different time periods and locations into a global reconstruction of the magnetic field over the past 9,000 years,” said Nilsson.
The Earth’s magnetic field is a dipole field because, like a bar magnet, it has two poles. The dipole moment (DM) measures the polarity of a field, or the separation of positive and negative charges. In this study, researchers reconstructed Earth’s DM for the last 9,000 years, which represents most of the Holocene epoch.
However, there are difficulties in interpreting paleomagnetic data in sediments, lavas, and artifacts during the Holocene.
“The challenges in reconstructing the Earth’s Holocene magnetic field are primarily related to 1) sparse data distribution, 2) chronological data uncertainties, and 3) temporal smoothing due to the gradual process by which sediments acquire magnetization,” the paper states. . The model the authors used to deal with these difficulties “…involves the compilation of the most recent archeomagnetic data and the exploitation of paleomagnetic directions from 10 sedimentary records strategically chosen based on data quality and geographic location.” Has gone. “
The Earth’s magnetic field also varies by location, with areas of strong and weak intensity. This can be different at the surface than at the core-mantle boundary (CMB). The researchers measured field intensity at the surface and at the CMB around 2020 and 650 BC. as part of their overall effort to understand SAA and geomagnetic reversal. ,
According to the authors, the SAA does not indicate an impending reversal of Earth’s magnetic poles.
“Based on the similarity to the anomalies being replicated, we estimate that the South Atlantic anomaly is likely to disappear within the next 300 years and that Earth is not heading for a polarity reversal,” Nilsson said.
North and South magnetic poles. Shutterstock
So the SAA would disappear, and the current state of Earth’s geomagnetism does not indicate an impending reversal. But one will come, and when it comes it will be the first time human civilization has had to contend with one. What does this mean for us and our civilization? What would that mean for the other inhabitants of the earth? What does the reversal do?
It is not clear what is causing the geomagnetic reversal. Some research suggests that this is a natural consequence of the changing nature of the Earth’s interior. Laboratory experiments confirm these spontaneous reversals. Other science suggests that external events can trigger reversals. An impact event can cause a reversal, or they can be triggered by a disruption in convection connecting to a continental plate mantle.
There is uncertainty about the implications of the reversal. Some scientists have speculated that the reversal may have triggered the extinction. If Earth’s magnetic shield is weakened enough during the reversal, the increase in solar radiation could have dire consequences for life on Earth. But the paleointensity evidence suggests that the gradient doesn’t vanish during a reversal and may not be weak enough to lead to much more. Overall, the evidence does not support a link between reversal and quenching.
It is uncertain what will happen to our technological civilization during the reversal. If the sun delivers a strong enough burst of energy to Earth, it can distort Earth’s magnetosphere and wreak havoc on navigation, electronics, and the electrical grid. A reversal can take several thousand years; Chaos reigns during this time, even before the bars attach themselves. At the very least, it would hamper compass-based navigation.
These screenshots of a NASA animation of a reversal show the chaotic nature of a reversal as it takes time for the poles to stabilize. Image Credits: Public Domain, https://commons.wikimedia.org/w/index.php?curid=1546763
Many animals use magnetoreception for navigation. Gray whales migrate up and down the west coast of North America, relying on magnetoreception to do so. Solar storms can temporarily distort the magnetosphere, and a 2020 study found a link between gray whale beaches and solar storms. Would geomagnetic reversal be more difficult for whales and other animals that rely on magnetism? It cannot be counted.
Could the South Pole anomaly provide clues as to what might happen during a geomagnetic reversal?
SAA is of concern because the weak magnetic field makes life difficult for the satellites. That’s because of the way it interacts with the Van Allen belts. The Van Allen Belts are regions of trapped charged particles around the Earth, and because of the SAA, the belts are closest to the Earth above the SAA. So whenever an orbiting satellite flies over the South Atlantic, it is exposed to increased radiation from the Van Allen Belts. Hubble makes no observations when it happens due to radiation SAA. NASA also says computers sometimes crash when the Space Shuttle passes SAA.
At the very least, there’s reason to believe that a pole flip can force us to adapt in a variety of ways. We don’t think about it much on a day-to-day basis, but we live in a geomagnetic environment that we cannot expect to be affected.
If humanity is still around during the next geomagnetic reversal, we will be forced to use methods that we do not yet fully understand. But humanity has survived by adapting for so long.
Maybe we’re fine.
This article is originally from . was published on universe today by Evan Gough. Read the original article here.
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