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Although the inspection of past reversals does not indicate biological extinctions, present society with its reliance on electricity and electromagnetic effects (e.g. radio, satellite communications) may be vulnerable to technological disruptions in the event of a full field reversal.
Glatzmaier and collaborator Paul Roberts of UCLA have made a numerical model of the electromagnetic, fluid dynamical processes of Earth's interior, and computed it on a Cray supercomputer. The results reproduced key features of the magnetic field over more than 40,000 years of simulated time. Additionally, the computer-generated field reversed itself.
Pole shift theories are also not to be confused with Geomagnetic reversal, the periodic reversal of the earth's magnetic field (effectively switching the north and south magnetic poles). Geomagnetic reversal has more acceptance in the scientific community than pole shift theories.
Recent work by scientists and geologists Adam Maloof of Princeton University and Galen Halverson of Paul Sabatier University in Toulouse, France, indicates that Earth indeed rebalanced itself around 800 million years ago during the Precambrian time period. They tested this idea by studying magnetic minerals in sedimentary rocks in a Norwegian archipelago. Using these minerals, Maloof and Halverson found that the north pole shifted more than 50 degrees — about the current distance between Alaska and the equator — in less than 20 million years. This reasoning is supported by a record of changes in sea level and ocean chemistry in the Norwegian sediments that could be explained by true polar wander, the team reports in the September–October 2006 issue of the Geological Society of America Bulletin.
Research using GPS, conducted by Geoffrey Blewitt of the University of Nevada, has shown that normal seasonal changes in the distribution of ice and water cause minor movements of the poles.
There is, however, a growing body of evidence that the Earth's magnetic field is about to disappear, at least for a while. The geological record shows that it flips from time to time, with the south pole becoming the north, and vice versa. On average, such reversals take place every 500,000 years, but there is no discernible pattern. Flips have happened as close together as 50,000 years, though the last one was 780,000 years ago. But, as discussed at the Greenland Space Symposium, held in Kangerlussuaq this week, the signs are that another flip is coming soon.
One of those signs is that the strength of the field has been falling by 5% a century recently. A similar (though more rapid) diminution accompanies the reversing of the sun's magnetic field, which happens every 11 yrs or so. Other evidence comes from old navigation records. Researchers such as Nils Olsen, of the Danish Space Center, have used such records to chart the growth of patches of abnormal magnetism. They are able to do so because these records use both compass bearings and astronomical observations to locate a vessel. The changing relationship between the two shows that patches of abnormal magnetism have been growing off SE Africa and in the S Atlantic.
Just when the magnetic field will flip is impossible to predict from what is known at the moment; the best guess is that there are still several centuries to go. Nor is it clear how long its protective shield will be down. (The record in the rocks is little help, since a geological eyeblink represents many human lifetimes.) But understanding how the magnetosphere works now should help to deal with the consequences if and when it vanishes.
The famous night-time auroras (borealis in the N, australis in the S) are the result of particles streaming in from the tail. But particles come in from the crown, as well, forming invisible daytime auroras that Dr Friis was among the first to study.
Like the weather on Earth, this space weather has consequences. If it gets nasty, communications satellites may be knocked out and radio communications within the atmosphere disrupted. In extreme circumstances, power grids may go down, too. Foul weather in space is also bad news for astronauts. A bad storm could kill an unshielded individual. But although the source of such foul space weather is known—it happens when giant flares on the surface of the sun pour out more protons and electrons than normal—the details depend on structures within the magnetosphere that are only now coming under scrutiny. Sometimes storms drift past the Earth with little impact. On other occasions they pummel the magnetosphere's crown to about half its normal distance from the Earth's surface. Furthermore, the magnetosphere's structure is layered, like an onion. The same type of particle can take on entirely different characteristics, depending on which layer it is in. The art of forecasting space weather is in its infancy.
Originally posted by hinky
I have often wondered if the poles shift, "would electricity and modern electronics continue to work as they were designed?".