Pole Shifts and Climatic Changes
In all of Earth’s history, the interval 42,000 years ago stands out as a remarkable period of upheaval. This was a time marked by rapid climatic shifts, widespread extinctions, and profound changes to the biosphere
The driving force behind these events, as suggested in a landmark study titled “A global environmental crisis 42,000 years ago“, appears to be the temporary collapse of Earth’s magnetic field, known as the Laschamps Excursion.
This brief magnetic pole reversal and a significant solar activity increase created a cascade of environmental consequences.
The Laschamps Excursion was a geomagnetic event where Earth’s magnetic poles weakened to less than six percent of their current strength and temporarily reversed.
This event lasted for about 800 years, with the most dramatic changes occurring over a 300-year period. During this time, the planet’s protective magnetic field, which shields us from cosmic radiation and solar winds, all but vanished.
Without this shield, Earth was bombarded with increased levels of ionizing radiation. Researchers argue that this surge in radiation likely caused an ozone layer collapse, amplifying ultraviolet radiation at the surface and triggering climate anomalies.
As the authors of the study noted:
“We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.”
This period coincides with the extinction of many megafaunal species and significant disruptions to human populations, such as the decline of the Neanderthals. Evidence suggests that humans sought refuge in caves, as their walls bear marks of protective pigments likely used to shield against increased UV radiation.
How the Magnetic Pole Works
Earth’s magnetic field is generated by the geodynamo process in the planet’s outer core, where the motion of molten iron creates electric currents. These currents produce the magnetic field, which is dynamic and constantly changing.
Magnetic poles are not fixed; they wander over time due to changes in the flow of molten metals within the core. Occasionally, these movements culminate in a magnetic reversal, where the north and south poles swap places.
Reversals are recorded in the alignment of magnetic minerals in ancient rocks, providing a timeline of Earth’s geomagnetic history.
Earth’s magnetic field has reversed hundreds of times in its 4.5-billion-year history. However, the frequency of reversals varies.
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Herb Rose
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The “ozone layer” is not blocking any UV. It is created by O2 molecules absorbing enough UV energy to split into oxygen atoms that then combine with an O2 molecule to form O3. The concentration of O3 in the “ozone layer” is 10ppm which can no more block 90+% off the UV from reaching the surface than a 1 cm^2 piece of black tape can block 90+% of visible light from passing through a 100,000 cm^2 pane of glass. It is the O2 and N2 that are absorbing the UV and converting it into ke. This absorbed energy produces the ozone in the stratosphere and the nitrogen-oxygen molecules in the higher atmosphere.
Molten iron is well above the Curie point and produces no magnetic field.
The Earth’s magnetic field is produced by the radioactive decay in the magma and its direction is determined by the magnetic field from the sun.
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A A Ron
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Understand your thoughts on the curie point but the magnetism is not produced naturally, from the material itself, but rather from the electric currents that flow thru the iron. Solid or molten, it don’t matter, the electron flow causes the magnetism.
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Herb Rose
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The “ozone layer” is not blocking any UV. It is created by O2 molecules absorbing enough UV energy to split into oxygen atoms that then combine with an O2 molecule to form O3. The concentration of O3 in the “ozone layer” is 10ppm which can no more block 90+% off the UV from reaching the surface than a 1 cm^2 piece of black tape can block 90+% of visible light from passing through a 100,000 cm^2 pane of glass. It is the O2 and N2 that are absorbing the UV and converting it into ke. This absorbed energy produces the ozone in the stratosphere and the nitrogen-oxygen molecules in the higher atmosphere.
Molten iron is well above the Curie point and produces no magnetic field.
The Earth’s magnetic field is produced by the radioactive decay in the magma and its direction is determined by the magnetic field from the sun.
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Michael Clarage
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Thank you.
There is certainly much to learn about how the Earth’s magnetic field affects everything from weather to extinctions.
I would say that there is no decent model for how the Earth’s magnetic field changes. I find the “dynamo” theories almost useless, and filled with contradictions and unreasonable assumptions.
I find a more satisfying model to be a dynamic interaction between the solar wind and current conduction in the Earth…but that is a much longer discussion.
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Jerry Krause
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First, Dr Wielicki you did not reference the study. Its title is Research finds the first Australian-based record of a major global event where the Earth’s magnetic field ‘switched’ – and north became south by Dr Agathe Lisé-Pronovost, University of Melbourne
Published 15 February 2021 by Earth Observation (???)
For more information I will try contact the author at the University of Melbourne. For I would like know what her scientific references are because the topic seems interesting if there is some observed basis for what we read.
Have a good day
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