#laschamp

[spacetimewithstuartgary]

Scientists recreate sound of Earth's magnetic flip 41,000 years ago

Approximately 41,000 years ago, Earth's magnetic field briefly reversed during what is known as the Laschamp event. During this time, Earth's magnetic field weakened significantly—dropping to a minimum of 5% of its current strength—which allowed more cosmic rays to reach Earth's atmosphere.

Scientists at the Technical University of Denmark and the German Research Center for Geosciences used data from ESA's Swarm mission, along with other sources, to create a sounded visualization of the Laschamp event. They mapped the movement of Earth's magnetic field lines during the event and created a stereo sound version which is what you can hear in the video.

The soundscape was made using recordings of natural noises like wood creaking and rocks falling, blending them into familiar and strange, almost alien-like, sounds. The process of transforming the sounds with data is similar to composing music from a score.

Data from ESA's Swarm constellation are being used to better understand how Earth's magnetic field is generated. The satellites measure magnetic signals not only from the core, but also from the mantle, crust, oceans and up to the ionosphere and magnetosphere. These data are crucial for studying phenomena such as geomagnetic reversals and Earth's internal dynamics.

The sound of Earth's magnetic field, the first version of the magnetic field sonification produced with Swarm data, was originally played through a 32-speaker system set up in a public square in Copenhagen, with each speaker representing changes in the magnetic field at different places around the world over the past 100,000 years.

[2sundowner69]

Sound of Earth’s magnetic flip 41 000 years ago

"Combining the satellite data with evidence of magnetic field line movements on Earth, European geoscientists mapped the so-called Laschamps event and represented it using natural noises like the creaking of wood and the crashing of colliding rocks.

The resulting compilation from the Technical University of Denmark and the German Research Center for Geosciences is unlike anything you've ever heard.

Generated by the swirling liquid metals in our planet's core, Earth's magnetic field reaches tens to hundreds of thousands of kilometers into space, protecting us all by deflecting atmosphere-stripping solar particles."

[xtruss]

Geoinformatics, Geodynamos & Superchrons: Will Humanity Survive Next Geomagnetic Pole Flip?

© Photo: Dr. Gary A. Glatzmaier, Los Alamos National Laboratory

The magnetic North Pole’s accelerating march toward Russia from Canada has fascinated and frightened millions of people around the world in recent years amid the prospect of a complete reversal of Earth’s Dipole Magnetic field. The director of the Russian Academy of Sciences’ Geophysical Center delves into the processes taking place under our feet.

The force generating the magnetic field shielding us from deadly solar winds has a fascinating life of its own, and one definitely worth exploring more closely if humanity is to get a fundamental understanding of the planet we call home, according to Veteran Russian Geophysicist, Geoinformatics Expert and Schmidt Institute of Physics of the Earth Head Researcher Anatoly Solovyov.

“The task of geoinformatics is to develop mathematical tools capable of handling the immense quantities of information that we began receiving recently thanks to modern networks digitally recording various natural process,” Dr. Solovyov explained.

“The ability to obtain new knowledge by processing large, often heterogeneous data from different disciplines in the field of Earth sciences, be it geomagnetism, gravity field anomalies, seismological observations, tsunamis,” and other phenomena, including the study of rapid fluctuations in Earth’s magnetic field has become possible only with modern technology and computing power, the academic said.

“Until recently, the characteristic temporal variations in the magnetic field were subject to study measured in centuries, with magnetic field reversals measured in the hundreds of thousands of years. With the advent of modern magnetic field recording systems, rapid variations in the magnetic field have been detected on characteristic time scales of one to ten years,” Solovyev noted. “We’ve learned to record such changes in the magnetic field – caused mainly by processes occurring at the boundary of the Earth’s liquid core, the mantle. We can observer them on the surface of Earth and from near-Earth space using high-precision geomagnetic observatories and low-orbit satellite systems.”

Dr. Anatoly Alexandrovich Solovyev, Geophysicist, Specialist in Geoinformatics, Doctor of Physical and Mathematical Sciences, Corresponding Member and Professor with the Russian Academy of Sciences. © Sputnik/Olga Merzlyakova

Earth Geomagnetic Poles’ Past…..and Future

Solovyev, coauthor of the Atlas of the Earth’s Magnetic Field, a comprehensive 2012 study of the evolution of Earth’s magnetic field from the years 1500 to 2010, and a top scholar involved in the creation of geomagnetic monitoring centers, says these observatories provide scientists the ability to study the temporal variability of Earths’ magnetic field over long periods of time.

“Modern models allow us to reconstruct the magnetic field not only of the past 500 years, but over tens of thousands of years, based on paleomagnetic and archeomagnetic data. We can say that, for example, that the movement of the North Magnetic Pole has significantly accelerated recently, and there is speculation that an inversion can be expected in the near future,” the academic explained.

Of course, there are counterarguments to the pole flip thesis, Solovyev noted.

“For example, 40,000 years ago, the Laschamp event geomagnetic excursion occurred when the dipole axis deviated significantly from the rotation axis. Thus, the North Magnetic Pole can shift to angles of 30-40 degrees, with this process accompanied by a major weakening of the magnetic field. 40,000 years ago, it weakened several times over compared to its present intensity. Nevertheless, everything later returned to its normal place.”

“On the scale we’re talking about, this is related to processes occurring in the liquid core. These have not been fully studied yet, because we only have indirect data. There’s actually very little data. Modern field observation systems were introduced only in the late 1980s, when digital data recordings became possible. Vector-based measurements using low-earth orbit satellites began to be conducted systematically only in the late 1990s, so a thorough reconstruction of the processes occurring in the liquid core, especially over such large intervals, is only possible using theoretical approximations,” Dr. Solovyev explained.

On top of that, it’s an issue of computing power, according to the academic. “For example, one of the latest achievements in the field of numerical modeling of such processes was the possibility to recreate variations associated with rapid changes to the magnetic field – so-called geomagnetic jerks, something achieved only in the last 50 years.”

Scientists have some idea about how the redistribution of magnetic flux occurs at the boundary of the liquid core and mantle, and theoretical concepts explaining the recent acceleration of the movement of the North Magnetic Pole in Russia’s direction, Solovyev said.

Life-Giving Force Shielding the Earth

As for the creation of Earth’s magnetic field itself, scientists postulate that the heterogeneity of states in the Earth’s mantle led to the non-stationary processes that generate the magnetic field.

“They are affected, in particular, by the Coriolis force, thermal convection, compositional convection. Such heterogeneities in Earth’s depths have apparently given rise to process of the creation of the geodynamo and its consequent maintenance,” Solovyev noted, referring to the theory about the mechanisms through which celestial bodies, including Earth, generate their magnetic fields.

“Geophysics is largely a science dedicated to heterogeneities and anomalies, starting with the fact that our planet consists of core-shells that are heterogeneous both in their composition and state of aggregation…In order to start up the dynamo in the form we see today, there must be a solid and a liquid core. The dynamo’s operating modes change depending on the radio of radii of the inner and outer cores. As the inner core grows, the dynamo’s operating modes (inversion frequency and intensity) also change,” the academic said.

In turn, the magnetic sphere contributed to the formation of life on Earth, given its role shielding us from the deadly effects of solar radiation.

At the same time, powerful magnetic storms can have an indirect impact on human health, with the dense flow of high-speed solar winds affecting the magnetosphere, in turn affecting atmospheric pressure, blood pressure, hormonal background, and various environmental factors.

Then, there is solar radiation. “At high altitudes, where high-energy particles penetrate close to the Earth’s surface and can reach the altitude of commercial aviation, the influence of precisely this radiation plan can be felt. Therefore, the [Russian] Space Weather Prediction Center provides a forecast for the level of geomagnetic activity on the Earth’s surface, including for the benefit of aviation. The trajectory of transpolar flights is adjusted accordingly depending on space weather. After all, in a powerful magnetic storm, a human being at such an altitude could receive a dose of radiation in one hour comparable to the average annual dose of radiation,” Solovyev noted.

Humans Adopt to Survive

Humanity has evolved by adapting to the natural changes in our geomagnetic environment over past millennia, and Dr. Solovyev is confident the species can adapt to abrupt changes in the magnetic field, should they take place once again.

“[Such changes] will not happen instantly. On a geological scale, it’s an instant, but on the scale we’re accustomed to, it’s quite a significant period of time, amounting to thousands of years, with the duration of the inversion itself lasting several thousand years…The magnetic field will gradually weaken. We have no documentary evidence about what will accompany this. Perhaps our species will be preserved, because the ionosphere and atmosphere will remain. Currents will be generated in the ionosphere, acting as a kind of shield in relation to those harmful particles flying toward us from the Sun, and may well protect us from solar radiation.”

Flips in the geomagnetic poles occur an average of 500,000 years or so, with the last one taking place about 750,000 years ago.

“No one knows when to expect the next one. It does not happen regularly. Moreover, periods know as superchrons were discovered when no inversion would occur for millions of years, with the field maintaining some fixed polarity. We know of three such superchrons,” Solovyev pointed out.

With homo erectus dating back about two million years, and the last inversion taking place three quarters of a million years ago, that means that the last time a pole flip occurred, it didn’t wipe out our ancestors.

More Data Can Lead to Fundamental Discoveries

Solovyev and his colleagues worked to build the Rotkovets Geobiosphere station in Popovka, Arkhangelsk region in 2012, providing researchers with pristine data free of electromagnetic interference and allowing for a range of geophysical observations.

“Since I have a background in engineering education, although it is a mathematical one, I would like to significantly expand the network of magnetic field observations using observatories of the highest class. This would make it possible to study the subtle effects in the change of the Earth’s magnetic field over a long-term basis,” Solovyev stressed.

With this knowledge, humanity would gain “information about the structure and arrangement of our planet. This is undoubtedly of fundamental importance,” he added.

“We will be able, for example, to study in greater detail the movement of the Magnetic North Pole, around which all the most intense changes in the magnetic field occur and, as a result, the most negative effects of space weather are observed. We’ll be able to adjust the trajectories of aircraft, be prepared for the impact of solar radiation on satellite systems. It’s a wide range of problems, from purely theoretical to important applied aspects,” Dr. Solovyev summed up.

— Sputnik International | Sunday August 18, 2024

[unhonestlymirror]

😍 And again, the northern lights in Ukraine

The phenomenon was observed in Kharkiv region, Donetsk region, and Dnipro region

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Living through Laschamp event😍😍😍

[itotalygetit]

When Earth Lost Its Magnetic Shield for 1,000 Years — The Laschamps Excu...

[yo-sostenible]

Un reciente estudio científico demuestra que el uso de cremas solares primitivas, prendas de vestir y la ocupación de cuevas como refugio fueron factores clave que permitieron a los humanos modernos adaptarse al aumento de radiación ultravioleta (UV) provocado por el desplazamiento de los polos magnéticos terrestres hace aproximadamente 40 000 años. Este fenómeno, vinculado a un evento de inversión magnética, elevó los niveles de exposición solar a extremos peligrosos. Mientras los Homo sapiens lograron sobrevivir gracias a estas innovaciones prácticas, los neandertales, al carecer de dichas estrategias de protección, se extinguieron durante el mismo período, marcando así un punto crítico en la evolución humana.  Hace aproximadamente 40 000 años, la Tierra experimentó un fenómeno geofísico crucial: el evento de Laschamp, una inversión geomagnética temporal que desplazó los polos magnéticos y debilitó la magnetosfera terrestre. Este evento expuso al planeta a niveles sin precedentes de radiación ultravioleta (UV), con consecuencias devastadoras para los ecosistemas.  Un estudio reciente, dirigido por investigadores de la Universidad de Michigan (EE.UU.) y publicado en la revista Science Advances, propone que los Homo sapiens lograron adaptarse a estas condiciones extremas gracias a innovaciones adaptativas. Entre ellas destacan el uso de pigmentos minerales como protectores solares primitivos, la confección de prendas para cubrir la piel y el aprovechamiento estratégico de cuevas como refugios naturales. Estas prácticas no solo mitigaron los efectos dañinos de la radiación, sino que también reflejan un pensamiento simbólico y práctico avanzado.  En contraste, los neandertales (Homo neanderthalensis), que no desarrollaron mecanismos de protección similares, enfrentaron un declive irreversible. Su extinción, coincidente en el tiempo con el evento de Laschamp, sugiere que la incapacidad para adaptarse a este estrés ambiental fue un factor determinante en su desaparición. Este hallazgo subraya cómo la capacidad de innovación marcó un punto de inflexión en la supervivencia diferencial entre especies humanas.  Alteración del campo magnético terrestre durante el evento de Laschamp Un equipo de investigación internacional ha creado un modelo 3D de alta resolución que simula el entorno espacial de la Tierra durante el evento de Laschamp, ocurrido hace aproximadamente 41 000 años. Mediante simulaciones magnetohidrodinámicas, reconstruyeron la estructura y dinámica del campo magnético global en este periodo, cuando los polos magnéticos sufrieron una inversión temporal. Este enfoque innovador permite analizar cómo el colapso parcial de la magnetosfera favoreció la penetración de radiación cósmica y partículas solares energéticas, factores críticos para estudiar su impacto en el clima, los ecosistemas y la supervivencia de especies humanas arcaicas Colapso magnético durante el evento de Laschamp «Durante este fenómeno, el campo magnético terrestre perdió el 90% de su intensidad actual —quedando reducido a apenas un 10%—, mientras los polos magnéticos migraron hacia latitudes ecuatoriales», detalla a la agencia SINC Agnit Mukhopadhyay, investigador de la Universidad de Michigan (EE.UU.) y coautor del estudio. Este proceso, conocido como excursión geomagnética, no es un evento aislado: registros geológicos indican que tales desplazamientos polares han ocurrido al menos 14 veces en los últimos 2.5 millones de años, según precisan los autores. El científico enfatiza que, aunque la reconfiguración magnética fue temporal —con una duración estimada de 2,000 años antes de recuperar su estabilidad—, sus repercusiones trascendieron el ámbito geofísico. «La exposición a radiación cósmica intensificada, las perturbaciones atmosféricas y las alteraciones en la capa de ozono generaron efectos ambientales en cascada. Estos no solo remodelaron patrones climáticos globales, sino que posiblemente influyeron en ciclos biogeoquímicos durante mi...

[danielwege-blog]

Polos magnéticos da Terra estão se invertendo e planeta pode ficar desprotegido da radiação

News https://portal.esgagenda.com/polos-magneticos-da-terra-estao-se-invertendo-e-planeta-pode-ficar-desprotegido-da-radiacao/

Polos magnéticos da Terra estão se invertendo e planeta pode ficar desprotegido da radiação

A inversão dos polos magnéticos da Terra é um fenômeno conhecido na história geológica do planeta. Embora pouco discutido no cotidiano, esse evento pode ter impactos significativos na vida terrestre e nas infraestruturas tecnológicas modernas.

A inversão dos polos magnéticos da Terra é um fenômeno conhecido na história geológica do planeta – Foto: Canva/ND

Como ocorre esse processo? Quando o campo magnético terrestre se enfraquece, os polos norte e sul invertem suas posições, algo que, segundo registros geológicos, já aconteceu diversas vezes ao longo de milhões de anos.

O evento de Laschamp e a inversão dos polos magnéticos

Um dos casos mais estudados desse fenômeno é o evento de Laschamp, ocorrido há cerca de 41 mil anos. Durante esse período, o campo magnético terrestre sofreu uma drástica redução de intensidade, chegando a desaparecer temporariamente em algumas regiões.

Esse enfraquecimento expôs a superfície do planeta a níveis elevados de radiação solar e cósmica, o que pode ter contribuído para a extinção de diversas espécies, incluindo o Homo neanderthalensis, segundo um artigo publicado pela revista Science.

O artigo salienta que evidências arqueológicas sugerem que grupos humanos primitivos podem ter buscado refúgio em cavernas para se proteger da radiação, o que pode estar relacionado ao aumento do registro de pinturas rupestres nesse período.

Essa hipótese, embora não seja conclusiva, reflete a capacidade de adaptação da humanidade diante de condições ambientais extremas.

O que os cientistas dizem sobre uma possível inversão dos polos magnéticos no futuro

Uma pesquisa da Nasa sugere que os polos magnéticos terrestres têm apresentado um enfraquecimento gradual nos últimos séculos – Foto: Canva/ND

Uma pesquisa da Nasa sugere que os polos magnéticos terrestres têm apresentado um enfraquecimento gradual nos últimos séculos, levantando questionamentos sobre a possibilidade de uma nova inversão de polaridade.

Caso isso ocorra futuramente, os impactos serão amplificados pela nossa dependência de tecnologias baseadas em eletricidade e telecomunicações.

Durante uma inversão magnética, as redes elétricas e sistemas de comunicação por satélite podem sofrer danos severos devido ao aumento da exposição à radiação espacial.

O resultado disso poderia comprometer desde a funcionalidade de aparelhos eletrônicos até a segurança de infraestruturas críticas, como hospitais e sistemas de transporte.

Possíveis impactos na saúde e no meio ambiente

Colapso temporário dos polos magnéticos podem afetar a camada de ozônio – Foto: Canva/ND

Além dos efeitos tecnológicos, um colapso temporário dos polos magnéticos podem afetar a camada de ozônio, aumentando a incidência de radiação ultravioleta na superfície terrestre, segundo a Nasa.

Isso resultaria em uma maior ocorrência de doenças como câncer de pele e outros problemas de saúde pública. Além disso, a radiação poderia impactar a biodiversidade, ameaçando ecossistemas que dependem de condições climáticas estáveis.

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[volcans-auvergne]

Puy de Dôme vu de Laschamps 15 Février 2025

[fromtheothersideby]

EARTH’S MAGNETIC SHIELD COLLAPSING https://2boomers.substack.com/p/earths-magnetic-shield-collapsing

Dive into the dramatic story of Earth's magnetic field during the Laschamp event, a geomagnetic excursion that occurred 41,000 years ago. This video explores how the planet's magnetic shield weakened to just 5% of its strength, exposing Earth to intense cosmic radiation and potentially altering the climate, ecosystems, and even the course of evolution.

[3acesnews]

Laschamp Event: Listen To The Eerie "Sound" Of Earth's Magnetic Fields Flipping

[the-eternal-quest-for-balance]

Space Weather, Hurricane, Galactic Cores, Laschamp | S0 News Sep.11.2024

[xneontragedyx]

41,000 Years Ago Earth’s Shield Went Down

Earth is naked without its protective barrier. The planet’s magnetic shield surrounds Earth and shelters it from the natural onslaught of cosmic rays. But sometimes, the shield weakens and wavers, allowing cosmic rays to strike the atmosphere, creating a shower of particles that scientists think could wreak havoc on the biosphere.

This has happened many times in our planet’s history, including 41,000 years ago in an event called the Laschamps excursion.

Cosmic rays are high-energy particles, usually protons or atomic nuclei, that travel through space at relativistic speeds. Normally, they’re deflected into space and away from Earth by the planet’s magnetic shield. But the shield is a natural phenomenon and its strength fluctuates, as does its orientation. When that happens, cosmic rays strike the Earth’s atmosphere.

That creates a shower of secondary particles called cosmogenic radionuclides. These isotopes become embedded in sediments and ice cores and even in the structure of living things like trees. There are different types of these isotopes, including ones like Calcium 41 and Carbon 14.

Showers of high-energy particles occur when energetic cosmic rays strike the top of the Earth’s atmosphere. Illustration Credit: Simon Swordy (U. Chicago), NASA.

Some of the isotopes are stable, and some are radioactive. The radioactive ones have half-lives ranging from only 20 minutes (Carbon 11) up to 15.7 million years (Xenon 129.)

When Earth’s shield weakens, more of these isotopes reach the planet’s surface and collect in sediments and ice. By studying these cores and sediments, scientists can determine the magnetic shield’s history. Their observations show that Earth experienced a geomagnetic excursion or reversal 41,000 years ago. It’s called the Laschamps excursion after the Laschamps lava flows in France, where geomagnetic anomalies revealed its occurrence.

Every few hundred thousand years, the Earth’s magnetic poles flip. North becomes South and vice versa. In between those major events are more minor events called excursions. During excursions, the poles shift around for a while without swapping places. The excursions weaken the Earth’s shield and can last from a few thousand to tens of thousands of years. When that happens, more cosmic rays strike the atmosphere, creating more radionuclides that shower down onto Earth.

Scientists often focus on one particular radioactive isotope in paleomagnetic studies. Beryllium 10 has a relatively long half-life of 1.36 million years and tends to accumulate on the soil surface.

Sanja Panovska is a researcher at GFZ Potsdam, Germany, who studies geomagnetism. At the recent European Geosciences Union (EGU) General Assembly 2024, Panovska presented new research on the Laschamps excursion. She found that during the Laschamps excursion, production of Be 10 was twice as high as normal.

To understand the Laschamps excursion more thoroughly, Panovska combined cosmogenic radionuclide and paleomagnetic data to reconstruct the Earth’s magnetic field at the time. She found that when the field decreased in strength, it also shrank. The transition from normal field to reversed field took about 250 years, and it stayed flipped for about 440 years. During the transition, the Earth’s shield weekend to as little as 5% of its normal strength. When it was fully reversed, it was at about 25% of its regular strength. This weakening allowed more Be 10 and other cosmogenic radionuclides to reach Earth’s surface.

Each map shows the intensity of Earth’s geomagnetic field at different snapshots in time, according to Panovska’s reconstructions that are constrained by both paleomagnetic data and records of cosmogenic beryllium-10 radionuclides. DM stands for Dipole Moment, which is a measure of the field’s polarity or separation of positive and negative. Age [ka BP] is the age measures in thousands of years before the present. Image Credit: Sanja Panovska.

These radionuclides do more than collect in sediments and ice. Some of them are radioactive. The weakening of the shield also weakened the ozone layer, letting more UV radiation reach Earth’s surface. The high-altitude atmosphere also cooled, which changed the wind flows. This could’ve caused drastic changes on the Earth’s surface.

For these reasons, the Laschamps event has been linked to the extinction of the Neanderthals, the extinction of Australian megafauna, and even to the appearance of cave art. Those links haven’t withstood scientific scrutiny, but that doesn’t mean that events like the Laschamps event aren’t hazardous. If it occurred now, it would knock out our power grids. The Earth’s equatorial region would light up with aurorae.

“Understanding these extreme events is important for their occurrence in the future, space climate predictions, and assessing the effects on the environment and on the Earth system,” Panovska said.

Scientists are learning that the magnetic shield isn’t static. There are anomalies. One of them is the South Atlantic Anomaly, a region where the magnetic field is weakest near Earth. When satellites pass over this region, they’re exposed to higher levels of ionizing radiation. The anomaly is likely caused by a reservoir of dense rock inside Earth, illustrating how complex the magnetic shield is.

Scientists are uncertain about what effect the cosmic rays have on life when the magnetic shield is weak. It’s tempting to correlate extinctions with events like the Laschamps excursion when they line up temporally. But the poles have shifted, weakened, and reversed many times and life is still here and still thriving.

If humanity lasts long enough, we’ll go through one of these reversals. Then we’ll know.

CATEGORIESCHEMISTRY, EARTH, SCIENCETAGSBERYLLIUM 10, COSMIC RAYS, COSMOGENIC RADIONUCLIDES, EXTINCTION, HALF LIFE DECAY, MAGNETIC SHIELD, PALEOMAGNETISM, RADIONUCLIDES

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[gaetaniu]

I raggi cosmici hanno attraversato l'atmosfera terrestre 41.000 anni fa: Nuove scoperte sull'escursione di Laschamps

Il campo magnetico terrestre ci protegge dalle pericolose radiazioni dello spazio, ma non è così permanente come si potrebbe credere. In occasione dell’Assemblea generale dell’Unione europea delle geoscienze, gli scienziati hanno presentato nuove informazioni su una “escursione” avvenuta 41.000 anni fa, durante la quale il campo magnetico del nostro pianeta è diminuito e i raggi spaziali nocivi…

[levysoft]

Il campo magnetico terrestre ci protegge dalla pericolosa radiazione dello spazio, ma non è così permanente come potremmo credere. "Gli scienziati dell'Assemblea generale dell'Unione europea per le geoscienze presentano nuove informazioni su un'"escursione" 41.000 anni fa in cui il campo magnetico del nostro pianeta è diminuito e i raggi spaziali dannosi hanno bombardato il pianeta."

Il campo magnetico terrestre avvolge il nostro pianeta dall'assalto delle radiazioni cosmiche che scorrono attraverso lo spazio mentre ci protegge anche dalle particelle cariche lanciate verso l'esterno dal sole. Ma il campo geomagnetico non è stazionario. Non solo il nord magnetico oscilla, allontanandosi dal vero nord (una posizione geograficamente definita), ma occasionalmente, si capovolge. Durante queste inversioni, il nord diventa sud, il sud diventa nord, e nel processo, l'intensità del campo magnetico diminuisce.

Ma c'è anche qualcosa chiamato escursioni del campo magnetico, brevi periodi in cui l'intensità del campo magnetico diminuisce e il dipolo (o due poli magnetici) che conosciamo può scomparire, sostituito da più poli magnetici. L'escursione di Laschamps avvenuta circa 41.000 anni fa è tra le meglio studiate. Presenta una bassa intensità del campo magnetico che implica meno protezione per la superficie terrestre dai raggi spaziali dannosi. Periodi di bassa intensità del campo magnetico potrebbero correlare a grandi sconvolgimenti nella biosfera.

Per vedere quando i raggi cosmici stavano bombardando pesantemente la superficie terrestre, gli scienziati possono misurare i radionuclidi cosmogenici nei nuclei sia del ghiaccio che dei sedimenti marini. Questi isotopi speciali sono prodotti dall'interazione tra i raggi cosmici e l'atmosfera terrestre; nascono dai raggi cosmici, quindi sono cosmogenici.

I tempi di minore intensità del campo paleomagnetico - meno schermatura - dovrebbero essere correlati a tassi più elevati di produzione di radionuclidi cosmogenici nell'atmosfera. Sanja Panovska, ricercatrice presso GFZ Potsdam, in Germania, presenterà le sue scoperte sulla relazione tra l'intensità del campo paleomagnetico e i nuclidi cosmogenici durante l'escursione di Laschamps, con particolare attenzione al clima spaziale, la prossima settimana durante l'Assemblea generale 2024 dell'Unione europea delle geoscienze (EGU).

Le variazioni dei radionuclidi cosmogenici come il berillio-10 forniscono un proxy indipendente di come è cambiata l'intensità paleomagnetica della Terra. In effetti, Panovska ha scoperto che il tasso medio di produzione di berillio-10 durante l'escursione di Laschamps era due volte superiore alla produzione attuale, il che implica un'intensità del campo magnetico molto bassa e molti raggi cosmici che raggiungono l'atmosfera terrestre.

Per strizzare più informazioni sia dai dati radionuclidi cosmogenici che da quelli paleomagnetici, Panovska ha ricostruito il campo geomagnetico utilizzando entrambi i set di dati. Le sue ricostruzioni mostrano che durante l'escursione di Laschamps, la magnetosfera si è ridotta quando il campo è diminuito drasticamente, "riducendo così la schermatura del nostro pianeta", ha detto.

"La comprensione di questi eventi estremi è importante per il loro verificarsi in futuro, le previsioni del clima spaziale e la valutazione degli effetti sull'ambiente e sul sistema terrestre".

[earthstory]

What is happening to the Earth’s Magnetic field? Is it the next disaster? Over recent weeks, you may have seen articles about the Earth’s Magnetic Field, specifically focused on the “South Atlantic Anomaly” – a zone in the Atlantic Ocean where the magnetic field is notably weaker than it is elsewhere on the Earth. This zone has been growing larger and the intensity overall weakening over the past few years. Is this something we should be concerned about? The best answer to that comes from geophysics and geology, which allow us to know how the magnetic field is generated and how it has behaved in the past.

Earth’s magnetic field is generated by convection in the outer core, a molten layer of iron-nickel metal that is capable of carrying and moving electrical charges. This is an extremely complicated process which humans currently don’t have the full capability to simulate. Imagine a river flowing – every little rock, every little difference in the flow path of the water, can cause turbulent flow in the river. Although there are dominant features to the convection in the outer core, complexity in the flow will show up as complexity at the surface. Earth’s magnetic field is dominantly a dipole field, meaning that it has north and south pole components closely aligned with the north and south poles around which the planet rotates. However, some portion of the magnetic field is always taken up by the more complicated components generated by the complex circulation in the core; this will cause some areas to be stronger and other areas to be weaker than the average magnetic field at any given time. Sometimes, the Earth’s dipole, north-south magnetic field appears to decrease in strength to zero, and then suddenly flip – with the south pole and north pole changing places. Because there are minerals on earth that record the magnetic field direction and intensity when they form, these magnetic reversals can be quite precisely recognized and studied. The last time the magnetic field fully flipped was about 781,000 years ago. Since then, the magnetic pole has mostly remained aligned with the north rotation pole, but the magnetic field is constantly in a state of change. The graph with this post shows the strength of the magnetic field over the past 100,000 years in the red curve, with today at 0 on the x axis. As you can see, the magnetic field has slightly weakened over the past 2000 years, but that was after a long period of strengthening of the field. Thus, weakening of the field right now is totally normal and not a sign of any pending 2020 apocalypse. At present, the South Atlantic Magnetic Anomaly has a strength that is about ½ that of the strongest magnetic field zone on Earth, and maybe about 3/4 that of the average, overall magnetic field. While this is the largest weak area on earth, you can also see from this graph that a weaker magnetic field than the one observed today is a common feature in recent geologic history, and does not portend an upcoming reversal. The blue line on that plot shows one other thing – how far away from the rotational pole is the current magnetic field. For most of the last 100,000 years the field has remained nearly north-south, but of course you can see one anomaly – 41,000 years ago, during an event called the Laschamp excursion, the north-south magnetic field weakened to nearly zero, and a weak east-west magnetic field seemed to dominate. Even though this event occurred and the total magnetic field shifted substantially, within a few centuries it snapped back to the previous orientation without reversing. If the magnetic field were to decay away, anything on the surface would be exposed to additional radiation and magnetic currents associated with the sun. This would generally be bad for humans, and in particular for electronic equipment, much of which would need additional shielding. In fact, satellites heading over the South Atlantic Magnetic Anomaly do need to prepare for these effects right now. But, if it helps to put your mind at ease – geologic history tells us that small changes in the magnetic field are normal and have happened constantly over the past 100,000 years. Not only do they not necessarily mean anything big is about to happen, we also see that it requires centuries of weakening before we would be concerned about the magnetic field truly dropping to zero, and that should be time for the next generations of electronics to receive extra shielding. If you’re wondering what the next hazard of 2020 will be, weakening of the magnetic field doesn’t have to be on your list, unless you’re designing a satellite. -JBB Image credit and references: https://eos.org/editors-vox/the-global-geomagnetic-field-of-the-past-hundred-thousand-years https://www.livescience.com/nasa-monitoring-dent-earth-magnetic-field.html https://www.nbcnews.com/science/science-news/dent-earth-s-magnetic-field-puzzles-scientists-n1237328