Posted on 11/09/2002 5:59:37 PM PST by Pokey78
Earth's magnetic field - the force that protects us from deadly radiation bursts from outer space - is weakening dramatically.
Scientists have discovered that its strength has dropped precipitously over the past two centuries and could disappear over the next 1,000 years.
The effects could be catastrophic. Powerful radiation bursts, which normally never touch the atmosphere, would heat up its upper layers, triggering climatic disruption. Navigation and communication satellites, Earth's eyes and ears, would be destroyed and migrating animals left unable to navigate.
'Earth's magnetic field has disappeared many times before - as a prelude to our magnetic poles flipping over, when north becomes south and vice versa,' said Dr Alan Thomson of the British Geological Survey in Edinburgh.
'Reversals happen every 250,000 years or so, and as there has not been one for almost a million years, we are due one soon.'
For more than 100 years, scientists have noted the strength of Earth's magnetic field has been declining, but have disagreed about interpretations. Some said its drop was a precursor to reversal, others argued it merely indicated some temporary variation in field strength has been occurring.
But now Gauthier Hulot of the Paris Geophysical Institute has discovered Earth's magnetic field seems to be disappearing most alarmingly near the poles, a clear sign that a flip may soon take place.
Using satellite measurements of field variations over the past 20 years, Hulot plotted the currents of molten iron that generate Earth's magnetism deep underground and spotted huge whorls near the poles.
Hulot believes these vortices rotate in a direction that reinforces a reverse magnetic field, and as they grow and proliferate these eddies will weaken the dominant field: the first steps toward a new polarity, he says.
And as Scientific American reports this week, this interpretation has now been backed up by computer simulation studies.
How long a reversal might last is a matter of scientific controversy, however. Records of past events, embedded in iron minerals in ancient lava beds, show some can last for thousands of years - during which time the planet will have been exposed to batterings from solar radiation. On the other hand, other researchers say some flips may have lasted only a few weeks.
Exactly what will happen when Earth's magnetic field disappears prior to its re-emergence in a reversed orientation is also difficult to assess. Compasses would point to the wrong pole - a minor inconvenience. More importantly, low-orbiting satellites would be exposed to electromagnetic batterings, wrecking them.
In addition, many species of migrating animals and birds - from swallows to wildebeests - rely on innate abilities to track Earth's magnetic field. Their fates are impossible to gauge.
As to humans, our greatest risk would come from intense solar radiation bursts. Normally these are contained by the planet's magnetic field in space. However, if it disappears, particle storms will start to batter the atmosphere.
'These solar particles can have profound effects,' said Dr Paul Murdin, of the Institute of Astronomy, Cambridge. 'On Mars, when its magnetic field failed permanently billions of years ago, it led to its atmosphere being boiled off. On Earth, it will heat up the upper atmosphere and send ripples round the world with enormous, unpredictable effects on the climate.'
It is unlikely that humans could do much. Burrowing thousands of miles into solid rock to set things right would stretch the technological prowess of our descendants to bursting point, though such limitations do not worry film scriptwriters. Paramount's latest sci-fi thriller, The Core - directed by Englishman Jon Amiel, and starring Hilary Swank and Aaron Eckhart - depicts a world beset by just such a polar reversal, with radiation sweeping the planet.
The solution, according to the film, to be released next year, involves scientists drilling into Earth's mantle to set off a nuclear blast that will halt the reversal.
Given that temperatures at such depths rival those of the Sun's surface, such a task would seem impossible - except, of course, in Hollywood.
Just wondering if these are similar to the computer models used to predict global warming. Programmer subcontracting?
Welcome to the next "scare the people" subject search.
Exactly! Think of the children!
Yes you are correct. The point that most seem to be missing is there are two potential events being discussed here...
1. Actual physical changes in the rotation character of the entire planet.
2. A change on the magnetic field of the planet.
One would be catastrophic, two would be a nuisance but not "earth shattering." Since the magnetic poles are established and maintained by the interaction of the solid inner core and the fluid outer core, changes occurring there, (flow rate/direction, inner core rotation speed, etc) would have little effect on the physical rotation of the entire planet.
Essentially, Item two does not cause item one to occur..
LOL!
Scientific maverick's theory on Earth's core up for a test
SF Chronicle ^ | Monday, November 29, 2004 | Keay Davidson
Posted on 12/05/2004 11:17:28 AM PST by SunkenCiv
http://www.freerepublic.com/focus/chat/1294934/posts
This is probably developed by the same idiots who advertise the "free" energy machines using the earth's magnetic fields in the popular science mags.
Kerry had a plan.
http://www.newscientist.com/news/news.jsp?id=ns99992152
Anomalies hint at magnetic pole flip
Nicola Jones
19:00 10 April 02
from New Scientist Print Edition
The Earth's magnetic poles might be starting to flip say researchers who have seen strange anomalies in our planet's magnetic field.
The magnetic field is created by the flow of molten iron inside the Earth's core. These circulation patterns are affected by the planet's rotation, so the field normally aligns with the Earth's axis - forming the north and south poles.
But the way minerals are aligned in ancient rock shows that the planet's magnetic dipole occasionally disappears altogether, leaving a much more complicated field with many poles all over the planet. When the dipole comes back into force, the north and south poles can swap places.
The last reversal happened about 780,000 years ago, over a period of several thousand years. Now Gauthier Hulot from the Institute of Earth Sciences in Paris and his colleagues think they have spotted early signs of another reversal.
South African anomaly
They used data from the Ørsted satellite to study strange variations in the Earth's magnetic field. In particular, one large patch under South Africa is pointing in the opposite direction from the rest of the Earth's field and has been growing for hundreds of years.
The anomalies have already reduced the overall strength of the planet's magnetic field by about 10 per cent. If they continue to grow at the same rate, the Earth's dipole will disappear within just two millennia.
But Ørsted is the first satellite to take a snapshot of the Earth's magnetic field for 20 years, and such scant data makes it difficult to predict future shifts.
"We can't really tell what will happen," says Hulot. "But we speculate that we're in an unusual situation that might be related to a reversal."
Journal reference: Nature (vol 416, p 620)
Reversals do not happen on any regular schedule, but at widely varying intervals.
We have no idea how long it takes for a reversal to happens, but 1000 years would be a reasonable guess, with a huge error factor.
This may affect how I buy real estate...
In 12th grade my friend spent two days of Physics class expounding on "The Hab Theory," a theory borrowed from a novel explaining how the earth was going to flip over soon. It's one of the few things I remember from that class, except for my other friend who used to spend the class reading the newspaper in the front row.
Has anyone stated the obligatory..."This is Bush's fault"?
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