https://www.npr.org/2021/02/18/969063568/ancient-trees-show-when-the-earths-magnetic-field-last-flipped-out
paleomagnetic reversals are correlated with isotope fluctuations in ancient trees preserved in new zealand bogs and allow precise dating of the last reversal some 42 000 years ago. the reversal lasted 400 years and is thought to have affected climate, winds, and especially the atmospheric ozone layer.
the magnetic field would be reduced to some 6 percent of normal, and the reduced ozone layer would have greatly increased the UV at the surface. the reversal is suspected of contributing to megafaunal extinctions and driving early humans intocaves. as shown by the sudden appearance of neanderthaler cave art.
i read some time ago that the earths magnetic field was currently increasing its wobbling. reversals are not rare. i dont think they are slow either
Fascinating.
Everyone should secure their cave now,
when the change comes it'll come fast.
I laugh at the property bubble blather,
The future is caves just as the past was.
most of the drama is still handwaving. they used to think that mars lost its atmosphere because the magnetic fieldcwent away and it was ablated by the unopposed solar wind, but nobody is sure
megafauna extnction data is too sparse tobe reliable, but the polar shift stuff is pretty clear. there was atotal reversal 40+K years ago and it was quick. most reversals occur at around 300 or 400 000 years apart and are pretty slow, like 10000 years. the neanderthalers mostly died out around then although there is a cave at gibraltar that was occupied until maybe 28000 years back, i think
the reversals are potentially significant but nobody agrees on how much. UV radiation, weather winds and ocean currents. 3D climate modeling is extremely hard to do because of neglected variables and pinball effects. the mantle and core shifts might result in supervulcanism and atmospheric cooing because of ash but its hard to model
of course if the meteorite hits first we wont get to see
I'd like a cave on the beach.
Quote from: Randy on February 20, 2021, 01:50:27 AM
I'd like a cave on the beach.
As long as the cave isn't going to be in a position where a tsunami washes in and snuffs you. While where I live at the moment isn't proof for
every cataclysmic event, (we do have an earthquake "issue" here in California), my particular location has survived two big ones- in '71 and '94, tsunamis and floods (no tall water above us) are not a consideration.