“The fossil record shows no drastic changes in plant or animal life,” says this article on SOTT. I beg to differ.
The earth’s magnetic field has flipped many times over the millennia, says the article. Magnetic reversals happen all the (geologic) time.
“Many doomsday theorists suggest that a magnetic reversal could lead to Earth’s destruction,” the article continues. “But would there be any dramatic effects?”
“The answer, from the geologic and fossil records we have from hundreds of past magnetic polarity reversals, seems to be ‘no,'” the article asserts. During the last major reversal about 780,000 years ago, the Brunhes-Matuyama reversal, “the fossil record shows no drastic changes in plant or animal life. Deep ocean sediment cores from this period also indicate no changes in glacial activity.”
“A weaker field would certainly lead to a small increase in solar radiation on Earth,” the article continues, “but nothing deadly.”
Nor would it happen fast. “The science shows that magnetic pole reversal is – in terms of geologic time scales – a common occurrence that happens gradually over millennia.”
I beg to differ on almost all counts.
Here’s how I put it in Magnetic Reversals and Evolutionary Leaps (citations are included in the book):
You’ll often hear that the most recent magnetic reversal occurred about 780,000 years ago at the Brunhes/ Matuyama boundary. But that date is way off the mark. At least ten magnetic reversals and excursions, probably many more, have ravaged our planet during the past 780,000 years.
Laschamp magnetic reversal
In 1967, Norbert Bonhommet and J. Babkine discovered a geomagnetic reversal in lava flows at Laschamp and Olby, at Chaîne des Puys (chain of volcanoes) in central France. Our magnetic field reversed about twenty to thirty thousand years ago, they announced, and then remained reversed for about ten thousand years. They called it the Laschamp magnetic reversal. Is it just a coincidence, Bonhommet asked, that the return to normal polarity corresponded with the end of an ice age?
Though later research placed the Laschamp event at around 44,000 years ago, its discovery made us aware that other magnetic reversals or excursions might have occurred.
Gothenburg magnetic excursion
The most recent excursion, the Gothenburg magnetic excursion, occurred about 12,350 years ago. During that excursion, magnetic intensity fell dramatically, to about twenty percent of the Holocene average. At the same time, magnetic inclination moved 180o. It also fluctuated, making wild swings of up 80°.
Mono Lake magnetic excursion
Another magnetic excursion, the Mono Lake excursion, occurred about 23,000 years ago. During the Mono Lake event, magnetic intensity fell ten times faster than normal.
Lake Mungo magnetic excursion
Before that came the Lake Mungo excursion of 33,500 years ago. And prior to that came the “real” Laschamp event of about 47,000 years ago, when magnetic intensity fell to less than 15% of today’s (All magnetic reversals and excursions show major decreases in intensity.)
See the cycle?
Those excursions struck like clockwork every 11,500 years, and they’ve been doing it for millions of years.
Geomagnetic reversals about 10,000 years apart have been found in the 65-million-year-old Deccan Traps, said geophysicist Vincent Courtillot. Indeed, 10,000-year hiatuses between lavas of opposite polarities are observed “frequently.”
Other scientists agree. Magnetic intensity fluctuations of from two to 30,000 years’ duration appear in the marine record as “tiny wiggles” and are therefore easy to overlook, said Steven Cande and Dennis Kent of Lamont-Doherty Earth Observatory. We believe that this type of behavior of tiny wiggles, they said, “may have characterized the geomagnetic dynamo throughout the Cenozoic [the last 65 million years].”
I think we’ll eventually find millions of such “tiny wiggles” in the geologic record.
Geomagnetic reversals and ice ages
But here’s the topper: Catastrophic cooling and rapid ice build-up accompanied many of those magnetic reversals and excursions. At least twelve ice ages can be correlated with magnetic reversals and excursions in the past two million years alone.
The Gothenburg magnetic excursion coincided with a period of short-term ice and snow, said Michael R. Rampino of NASA, as did the Lake Mungo excursion, when rapid cooling immediately followed a period of warmth.
The Mono Lake magnetic excursion coincided with glaciation; the Blake magnetic reversal at the end-Eemian coincided with glaciation, as did Biwa I, Biwa II, and Biwa III.
Each of those catastrophic cooling episodes, said Rampino, “may have been triggered by a magnetic excursion. The Earth’s magnetic field may be directly modulated by precession.”
So there you have it.
Polarity reversals, equinoctial precession, and ice ages, all march to the same drummer. As do extinctions and new species appearance. Toss in the specter of massive amounts of radioactivity falling on your head, and you’ve got the picture.
Look at the number of catastrophes that have befallen our planet in sync with magnetic reversals during the last 115,000 years alone:
Catastrophes in sync with equinoctial precession
(kya = thousands of years)
115 kya – Blake magnetic reversal. Spikes in radioactive carbon-14 and strontium. Ice age begins abruptly following a period of warmth similar to today’s. Sea levels surge 20 feet, then plunge at least 50 feet, in less than a century.
43 kya – Laschamps magnetic excursion. Beryllium spike (three times normal). Carbon-14 spike (two times normal). Ice age begins abruptly. Rising reefs.
34 kya – Lake Mungo magnetic excursion. Beryllium spike. Carbon-14 spike (almost twice normal). Short-term ice build-up, then ice age ends abruptly. Lake Missoula flood. Lake Bonneville flood. Intensive volcanism. Neanderthal disappears.
23 kya – Mono Lake magnetic excursion. Ice age begins abruptly. Major volcanism. Spikes in radioactive beryllium and carbon-14 (four to five times normal). Mass extinction. European forest elephant disappears. Mammoths clobbered.
11 kya – Gothenburg magnetic excursion. Mass extinction; 72% of large mammal species go extinct, whereas only 10% of small mammal species disappear. Spikes in radioactive carbon-14 (three to four times normal), beryllium-10 (two to three times normal), iridium (two to three times normal). Spikes in CO2 and many other elements. Rapid and severe ice build-up, then ice age ends in less than 20 years and today’s warm period begins. Worldwide volcanism. Nile River flood. Connecticut River flood. Lake Missoula flood. Lake Bonneville flood. Gulf of Mexico flood. St. Lawrence River flood. Worldwide tectonic uplift. Creation of the Carolina Bays.
And that brings us to today, frighteningly unprepared for the next beat of the magnetic-reversal cycle.
(By the way, I think those spikes in radioactive beryllium, strontium, iridium and carbon-14 lead to mutations and evolutionary leaps. And they say there would be “no dramatic effects”?)
See entire SOTT article:
Thanks to Peter Lamb for this link