When the poles flip, researchers call it a geomagnetic turnaround, and the last one took place about 780,000 years earlier. It takes in between 2,000 and 7,000 years for the poles to reverse. The evidence is contained in magnetic minerals inside rocks. Magnetic minerals record the strength and direction of Earths magnetic fields when theyre locked in place, either as sediments or in magma. The study of magnetism in Earths ancient rocks is called paleomagnetism.
Among the most intriguing discoveries about Earth in the previous couple of years worries the Earths magnetic poles. Paleomagnetic records show that the poles have actually flipped locations 183 times in the last 83 million years. Thats about every 450,000 years typically, though there were ten million years between turns in a minimum of 2 cases.
The Earths electromagnetic field is experiencing some quick changes today, however researchers state that has no relation to pole turning.
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Currently, theres an area in the South Atlantic where the geomagnetic field is rapidly weakening. Its called the South Atlantic Anomaly (SAA), and its led to concerns about its role in geomagnetic reversal if any.
The South Atlantic Anomaly in 2020. Image Credit: Christopher C. Finlay, Clemens Kloss, Nils Olsen, Magnus D. Hammer, Lars Tøffner-Clausen, Alexander Grayver & & Alexey Kuvshinov– “The CHAOS-7 geomagnetic field design and observed modifications in the South Atlantic Anomaly”, Earth, Planets and Space, Volume 72, Article number 156 (2020 ), https://earth-planets-space.springeropen.com/articles/10.1186/s40623-020-01252-9, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=99760567
Scientists have known about the SAA for a while. What they didnt understand for sure was if the anomaly symbolizes an impending geomagnetic reversal. If the SAA is heralding an approaching reversal, Researchers behind a new study looked at proof going back thousands of years to identify.
In the past 180 years, the strength of Earths electromagnetic field has actually decreased by about 10 percent. Throughout that same time, the size of the SAA has grown. Researchers have speculated that these events might be connected to a geomagnetic turnaround.
A new study in the Proceedings of the National Academy of Sciences looked for a link between the SAA, the reducing field strength, and geomagnetic reversals. Its entitled “Recurrent ancient geomagnetic field abnormalities shed light on future development of the South Atlantic Anomaly.” The lead author is Andreas Nilsson, a geologist at Lund University in Sweden.
” We have actually mapped changes in the Earths electromagnetic field over the previous 9,000 years, and anomalies like the one in the South Atlantic are probably repeating phenomena connected to corresponding variations in the strength of the Earths electromagnetic field,” Nilsson stated in a news release.
Illustration of the unnoticeable electromagnetic field lines generated by the Earth. Unlike a classic bar magnet, the matter governing Earths electromagnetic field relocations around. The circulation of liquid iron in Earths core creates electric currents, which develop the electromagnetic field. Credit and copyright: Peter Reid, University of Edinburgh.
The scientists analyzed three kinds of proof: solidified volcanic samples, sediment drill cores, and charred historical artifacts. Artifacts like clay pots that have been heated above 580 Celsius (1076 F) allow magnetic products to reorient themselves to the Earths electromagnetic field at the time. All 3 kinds of evidence serve as time pills that catch a photo of Earths magnetism at a specific time.
” We have established a new modelling method that connects these indirect observations from various time periods and locations into one international restoration of the magnetic field over the past 9,000 years,” said Nilsson.
Earths electromagnetic field is a dipole field because it has two poles, like a bar magnet. The dipole minute (DM) determines a fields polarity or separation of favorable and negative charges. In this study, the scientists rebuilded Earths DM for the prior 9,000 years, that makes up the bulk of the Holocene date.
However there are troubles analyzing the paleomagnetic information in sediments, lava, and artifacts throughout the Holocene.
” The difficulties with Holocene geomagnetic field reconstructions are mainly associated to the 1) sporadic data circulation, 2) chronological information unpredictabilities, and 3) temporal smoothing due to the gradual process by which sediments acquire a magnetization,” the paper states. The design the authors used to handle these troubles includes benefiting from “… the most up-to-date archaeomagnetic information collection and paleomagnetic directions from 10 sediment records, tactically selected based on information quality and geographic location.”
This figure from the research study reveals the groups reconstruction of the Earths DM over the previous 9,000 years. They based their restoration on various previous measurements of the Earths DM.
Earths electromagnetic field also varies by location, with areas of both more powerful and weaker intensity. It can be different in the worlds surface area compared to the core-mantle limit (CMB.) The scientists determined the intensity of the field at the surface area and the CMB at 2020 and 650 BCE as part of their overall effort to understand the SAA and geomagnetic reversals.
According to the authors, the SAA doesnt suggest an approaching turnaround of Earths magnetic poles.
” Based on similarities with the recreated anomalies, we forecast that the South Atlantic Anomaly will most likely vanish within the next 300 years and that Earth is not heading towards a polarity turnaround,” said Nilsson.
This figure from the study shows the geomagnetic field strength for Earths surface and at its core-mantle border in the years 2020 and 600 BCE. The grey regions in C and D highlight regions where the teams model is more uncertain. Image Credit: Nilsson et al. 2022.
The SAA will vanish, and the existing state of Earths geomagnetism does not show an impending turnaround. One will come, and when it does, itll be the first time human civilization will have to deal with one. What will it mean for us and our civilization? What will it suggest for Earths other inhabitants? What triggers turnarounds?
Its not clear what causes geomagnetic turnaround. Some research study shows that its a natural repercussion of the altering nature of Earths interior.
If Earths magnetic shield damages enough during a reversal, the increase in solar radiation could have alarming consequences for life on Earth. Paleointensity proof reveals that the shield doesnt disappear throughout a reversal and might not damage enough to be of much repercussion.
When the Sun produces an effective enough blast of energy at the Earth, it can warp the Earths magnetosphere and wreak havoc on navigation, electronic devices, and the power grid. A turnaround can take a number of thousand years; during that time, theres chaos prior to the poles sort themselves out.
These screenshots from a NASA animation of a turnaround show the disorderly nature of a turnaround, as the poles take some time to support. Image Credit: Public Domain, https://commons.wikimedia.org/w/index.php?curid=1546763
Numerous animals use magnetoreception to browse. Grey whales move up and down the west coast of North America and may depend on magnetoreception for assistance. Solar storms can momentarily warp the magnetosphere, and a 2020 research study discovered a connection between grey whale beachings and solar storms. Would a geomagnetic reversal be hard on whales and other animals that depend on magnetoreception? It cant be passed over.
Can the South Pole Anomaly offer a clue to what might occur during a geomagnetic turnaround?
The SAA is concerning since the weakened magnetic field makes life challenging for satellites. The Van Allen Belts are zones of caught charged particles that surround Earth, and because of the SAA, the belts are closest to Earth over the SAA. Whenever a satellite orbiting Earth passes over the South Atlantic, it faces a duration of increased radiation from the Van Allen Belts.
At the minimum, theres factor to believe a pole turn could require us to adjust in numerous methods. We dont think of it much in life, however we live in a geomagnetic environment over which we cant possibly hope to have any influence.
If humankind is still around during the next geomagnetic reversal, well be forced to adapt in ways we dont completely understand. But humanity has actually endured this long by adjusting. Perhaps well be great.
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One of the most intriguing discoveries about Earth in the past couple of decades concerns the Earths magnetic poles. The SAA will vanish, and the current state of Earths geomagnetism doesnt show an impending turnaround. If Earths magnetic shield compromises enough throughout a turnaround, the boost in solar radiation could have dire effects for life on Earth. When the Sun gives off a powerful adequate blast of energy at the Earth, it can warp the Earths magnetosphere and wreak havoc on navigation, electronic devices, and the power grid. The Van Allen Belts are zones of trapped charged particles that surround Earth, and because of the SAA, the belts are closest to Earth over the SAA.