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Strategies & Market Trends : Taking Advantage of a Sharply Changing Environment
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To: Doug R who wrote (4509)2/18/2021 10:32:26 PM
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NPR now putting it out there - 4509
Ancient Trees Show When The Earth's Magnetic Field Last Flipped Out
February 18, 2021

"The Earth is a giant magnet because its core is solid iron, and swirling around it is an ocean of molten metal. This churning creates a huge magnetic field, one that wraps around the planet and protects it from charged cosmic rays coming in from outer space."

Inside trees that lived during the last magnetic flip, the researchers and their colleagues looked for a form of carbon created when cosmic rays hit the upper atmosphere. More of these rays come in when the magnetic field is weak, so levels of this carbon go up.

The trees, with their calendar-like set of rings, took in this kind of carbon and laid it down as wood. That let the researchers see exactly when levels rose and peaked and then fell again. One tree in particular had a 1,700-year record that spanned the period of the greatest changes.

By creating a precise timeline, the research team was able to compare the magnetic field's weakening to other well-established timelines in the archaeological and climate records.

"We really think actually there's quite considerable impacts going on here," says Cooper.

They also turned to advanced climate modeling to try to understand how the magnetic changes would have affected conditions on the planet. The ozone layer, in particular, would have taken a beating.

"If you damage the ozone layer, as we've found out, you change the way in which the sun's heat actually impacts the Earth," says Cooper. "And as soon as you start doing that, you change weather patterns because wind directions and heating goes AWOL, goes all over the place."

If the sun went through one of its periodic conniptions when the strength of the Earth's magnetic field was turned way down, he says, a solar flare or storm would have sent a burst of radiation that could have had massive consequences for people living back then.

James Channell, 1627 a geologist at the University of Florida [...] has previously written about the possibility that magnetic field weakening was linked to die-offs of large mammals, so he was "thrilled" to see someone else connecting those two things. Large mammals, he notes, are long-lived and susceptible to damage from prolonged exposure to the ultraviolet radiation that would increase during periods when the magnetic field was weak.
"From what we know about field strength through time, over the last hundred thousand years," says Channell, "there does appear to be a linkage between extinctions and low geomagnetic field strength."

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