Earth's magnetic field is fading. Today it is about 10 percent weaker than it was when German mathematician Carl Friedrich Gauss started keeping tabs on it in 1845, scientists say.
If the trend continues, the field may collapse altogether and then reverse. Compasses would point south instead of north.
Not surprisingly, Hollywood has already seized on this new twist in the natural-disaster genre. Last year Tinseltown released The Core, a film in which the collapse of Earth's magnetic field leads to massive electrical storms, blasts of solar radiation, and birds incapable of navigation.
Entertainment value aside, the portrayal wasn't accurate, according to scientists who say the phenomenon of Earth's fading magnetic field is no cause to worry.
"The field has reversed many times in the past, and life didn't stop," said Gary Glatzmaier, an earth scientist and magnetic field expert at the University of California, Santa Cruz.
Glatzmaier is keeping an eye on our planet's weakening magnetic field as he tries to learn more about how Earth's geodynamo works. The geodynamo is the mechanism that creates our planet's magnetic field, maintains it, and causes it to reverse.
Magnetic Shield
Earth's geodynamo creates a magnetic field that shields most of the habited parts of our planet from charged particles that come mostly from the sun. The field deflects the speeding particles toward Earth's Poles.
Without our planet's magnetic field, Earth would be subjected to more cosmic radiation. The increase could knock out power grids, scramble the communications systems on spacecraft, temporarily widen atmospheric ozone holes, and generate more aurora activity.
A number of Earth's creatures, including some birds, turtles, and bees, rely on Earth's magnetic field to navigate. The field is in constant flux, scientists say. But even without it, life on Earth will continue, researchers say.
"There are small fluctuations, which lead to nothing, and large ones, which we know from the geologic record are associated with reversals," said Peter Olson, a geophysicist at Johns Hopkins University in Baltimore, Maryland.
When molten lava erupts onto the Earth's crust and hardens, it preserves a snapshot of Earth's polarity, much in the way that iron filings on a piece of cardboard align themselves to the field of a magnet held beneath it.
According to Earth's geologic record, our planet's magnetic field flips, on average, about once every 200,000 years. The time between reversals varies widely, however. The last time Earth's magnetic field flipped was about 780,000 years ago.
"We hear the magnetic field today looks like it is decreasing and might reverse. What we don't hear is it is on a time scale of thousands of years," Glatzmaier said. "It's nothing we'll experience in our lifetime."
But several generations from now, humans just may witness a reversal. By then, Glatzmaier said, scientists will better understand the process and be prepared to cope with the effects.
Geodynamo
Scientists believe the magnetic field is generated deep inside the Earth where the heat of the planet's solid inner core churns a liquid outer core of iron and nickel.
The solid inner core is thought to be a mass of iron about the size of the moon that is heated to several thousand degrees Fahrenheit. Heat radiated by this inner core builds up at its boundary with Earth's liquid outer core, causing the fluid there to expand.
"When it expands it becomes a little less dense [and more] buoyant. So it starts to rise. That's convection," Glatzmaier said. "Hot fluid rises, then cools off and sinks again."
The convection generates an electric current and, as a result, a magnetic field.
Additional currents are created as Earth cools. Some of the molten iron solidifies onto the inner core, releasing lighter material in the process. The rotation of the Earth also generates forces that curve the flow of fluid as it rises, twisting the magnetic field.
All of these currents constantly replenish the magnetic field, a maintenance process that prevents it from decaying.
Typically each newly generated field lines up in the direction of the existing magnetic field. But every now and again, some force will cause the new field to line up in the opposite direction. This process can lead to a net weakening of Earth's magnetic field.
Over time a new field can continue to grow. This further weakens the original magnetic field. If the process continues, the two fields would eventually cancel each other out. Earth's magnetic field would collapse and then, maybe, flip.
"But more likely than not what will happen is the original [field] will get stronger again and overwhelm the instability," Glatzmaier said.
So, is the field FADING, or is it becoming LESS COHERENT? Is it actually getting WEAKER, or is it's direction turning in on itself, with a possible re-aligning in the opposite direction?
I saw a documentary on this issue, but the understanding I was left with was that the field is beginning to become less coherent, in the sense that the field is possibly slowly turning in on itself as it might be re-aligning in the opposing direction.
Maybe that explains that weird place somewhere in the states, where you can stand at a 45 degree angle, and not tip over because you feel gravity pulling on you like normal. You also THINK you're standing perfectly straight... Never seen anything like it, but maybe it's due to the change in the magnetic field...
Maybe absense of magnetic field will in fact cause massive electrical storms, solar radiation, etc. and will be the new world-wide disaster like the 40 day and night rain described in the Bible?
I was learning about this in science the other day, I thought it was amazing. From what I gathered, every - I think it was 200,000 years, or something like that - the field weakens, then flips and is strong again. But it won't happen suddenly, it'll take about 200 years to completely flip. And it hasn't actually flipped for 750,000 years, a much longer time than the usual 200,000.
"It's just something Gandalf said, "Don't you lose him Samwise Gamgee", and I don't mean to."
This is no joke! I've moved it to the Science & Tech forum as there is solid science underlying this topic.
As I understand it, i believe the field is becoming less coherent over time as it moves through this switching process. The movie The Core wasn't based on the samescience - it insinuated that humans were responsible for screwing it up. What we are seeing today is a completely natural, recurring phenomenon. I'm curious what side effects will come along with it though including the possibility of prolonged and reduced solar radiation protection..
I have a feeling that such a long period between field shifts might lead to other complications with the reversal than may normally be experienced on earth. Such a long period has to be for a reason... I wouldn't be surprised if "the skies were rolled back as a scroll"...
I agree, Sean. This is BIG. But I doubt we'll be around when the field reverses...
MrJukoVette said this in post #3 : Maybe absense of magnetic field will in fact cause massive electrical storms, solar radiation, etc. and will be the new world-wide disaster like the 40 day and night rain described in the Bible?
Or we or our children could live to see the next ice age.
Global warming may be the calm before the storm. It seems as though each interglacial phase in the history of earth has had a major global thaw before launching into the next ice age.
Because of human activity, the earth's magnetic field is weakening. Interglacial and glacial phases are dependent upon the severity of shifting of earth's magnetic field.
If we've based all of our calculations regarding earth's age on the soil, have we then also taken into consideration the varying strength of the magnetic field, regardless of it's alignment? Could the strength of the field affect things like carbon dating, or the actual effect of gravity around the globe?
We know that if there's enough magnetic force acting on an object in opposition to the gravitational pull acting on the same object, then the object will levitate (mag-lev trains for example, but apparently even liquid water...). If the magnetic field was either stronger or weaker, reversed in polarity, etc, then that could have drastic effects on EVERYTHING that we take for granted regarding the earth's properties and the way we believe the atmosphere has been operating throughout the ages...
Carbon dating can be misleading and inconclusive. Scientists are now speculating that because of the earth's corrosion, carbon dating may never be an exact science. It's also impossible to determine the appropriate levels of carbon that existed on earth through the ages. Atmospheric shifting and changes have been occurring since the beginning of time.
So far, nothing is know conclusively about whether gravity has been affected, but it is predicted that it will be in the future, so much so that birds may not be able to take flight and humans may not be able to stand upright without tipping over.
What is known, is that earth's magnetic field is how birds sense when and how far to migrate to their desired destination. You may hear reports of Canadian geese flying further south than they did twenty years ago, and most of the time they will not fly back to where they came from. That is because earth's magnetic field has weakened so much that it has damaged birds senses and they simply can't find their way back home.
Because of human activity, the earth's magnetic field is weakening. Interglacial and glacial phases are dependent upon the severity of shifting of earth's magnetic field.
You wonder how anything ever happened before humans came along to cause it.
Blaming ourselves for magnetic field flips is like mayflies blaming themselves for a sunset.
Human activity/overpopulation isn't speeding the process up?
The causes for magnetic flips are not entirely understood, but the thinking goes along like this:
"Earth's magnetic field is thought to be generated deep inside the planet. An inner core of solid iron is surrounded by an outer core of molten iron. They rotate at different rates, and the interaction between the regions creates what scientists call a "hydromagnetic dynamo." It's something like an electric motor, and it generates a magnetic field akin to a giant bar magnet." (from an article at Space.com, which is about what I recall from those long-ago days as a geology major)
You tell me how a swarming mass of humans affects the molten outer core some 1,800 miles beneath the earth's surface.
You tell me how a swarming mass of humans affects the molten outer core some 1,800 miles beneath the earth's surface.
I have posted many things about "swarming masses of humans" in these forums, and will probably do so again in a couple of weeks. You seem like someone I would enjoy having a scientific debate with.
Yeah, I think I'll stick in this CD and call it a night.
This is about all I need to know about magnetic fields...unless I just start flying into the air for no reason...
But I'll still enjoy yo discussion....while listening to all there is for me to know about magnetic fields....
09-15-2004 06:54 AM
