Privileged Planet: magnetic field cycles over time (Introduction)

by David Turell , Wednesday, August 18, 2021, 18:39 (982 days ago) @ David Turell

It has had weak and strong periods over time:

https://phys.org/news/2021-08-evidence-million-year-earth-magnetic-field.html

"The findings of a new study by the University of Liverpool provides further evidence of an approximately 200 million-year long cycle in the strength of the Earth's magnetic field.

"Researchers performed thermal and microwave (a technique which is unique to the University of Liverpool) paleomagnetic analysis on rock samples from ancient lava flows in Eastern Scotland to measure the strength of the geomagnetic field during key time periods with almost no pre-existing, reliable data. The study also analyzed the reliability of all of the measurements from samples from 200 to 500 million years ago, collected over the last ~80 years.

"They found that between 332 and 416 million years ago, the strength of the geomagnetic field preserved in these rocks was less than quarter of what it is today, and similar to a previously identified period of low magnetic field strength that started around 120 million years ago. The researchers have coined this period "the Mid-Palaeozoic Dipole low (MPDL)."

"...the study supports the theory that the strength of the earth's magnetic field is cyclical, and weakens every 200 million years, an idea proposed by a previous study lead by Liverpool in 2012. One of the limitations at the time was the lack of reliable field strength data available prior to 300 million years ago, so this new study fills in an important time gap.

"The Earth's magnetic field shields the planet from huge blasts of deadly solar radiation. It is not completely stable in strength and direction, both over time and space, and has the ability to completely flip or reverse itself with substantial implications.

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"A weak field also has implications for life on our planet. A recent study has suggested that the Devonian-Carboniferous mass extinction is linked to elevated UV-B levels, around the same as the weakest field measurements from the MPDL.

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"'Our findings, when considered alongside the existing datasets, supports the existence of an approximately 200-million-year long cycle in the strength of the Earth's magnetic field related to deep Earth processes. As almost all of our evidence for processes within the Earth's interior is being constantly destroyed by plate tectonics, the preservation of this signal for deep inside the Earth is exceedingly valuable as one of the few constraints we have.'"

Comment: The implication is obvious. We need a strong magnetic filed to protect us. The evidence of past weak and strong cycles has us wondering about the possible appearance of a weak cycle. Since the Earth evolved to this life-supporting state, I think God has arranged for it to stay that way.