Earth's Magnetic Field Weakens 10 Percent

caryw writes "Interesting story from the AP. 'The strength of the Earth's magnetic field has decreased 10 percent over the past 150 years, raising the remote possibility that it may collapse and later reverse, flipping the planet's poles for the first time in nearly a million years, scientists said Thursday. At that rate of decline, the field could vanish altogether in 1,500 to 2,000 years, said Jeremy Bloxham of Harvard University. Hundreds of years could pass before a flip-flopped field returned to where it was 780,000 years ago. But scientists at a meeting of the American Geophysical Union cautioned that scenario is an unlikely one. "The chances are it will not," Bloxham said. "Reversals are a rare event."'"

Comments

Not weakened 10%!

[Anonymous Coward]

The north-south polarity may have weakened 10%. The totality of the field remains the same. The north-south polarity appears to be randomizing as it realigns into a south-north flip.

Paleomagnetism is Real.

[cupofjoe]

I, too, agree with those who have cited the period nature of these types of events.

The scientific tracking of this phenomenon - within the bounds of a burgeoning field called paleomegnetism - has shown that such events have been seen already.

If I remember correctly, the seafloor around the Mid-Altantic Ridge shows local magnetic field lines (embedded in rock) that exhibit directional reversal on a regular basis. The regular, gradual creation of new seafloor on both sides of this band of spreading magma locks in the direction of Earth's general magnetic field at the time of formation - showing, some think, that these occurrences are regular and repeatable.

And yes, we're definitely overdue. But, we're also overdue for a planet-killing asteroid impact, so I guess there's nothing to worry about. What's a little field instability among friends?

It should be noted, however, that there is some notion that periods during which magnetic shielding is lost probably does wonders for increasing evolutionary branching. Think of all the natural selection that gets done under such extreme environmental pressure...

Sorry for the ramble. IANAP, by the way, but IAAPT (teacher).

Re:This was on NOVA a week or two ago

[dgodwin]

I didn't think it was too "alarmist" as towards the end they talk about the only major negative effects of a weakened magnetic field and eventual switch is a slight increase in cancer (compared with all the cancer in the world as we know it today.) It also presented the possibility of having more than 2 poles, and a positive effect of the was having the auroras being visible all over the Earth. I showed this in my Earth Science classes this weeek, as we just started talking about how magnetic reversals are recorded in igneous rock, and is one of the pieces of evidence for sea floor spreading and plate tectonic theory.

Re:Question is, what does that mean...

[Ranten_N_Raven]

Time to panic!

Didn't you see the movie "The Core?" (It stars the lucious Hillary Swank and shows the devastation that awaits a loss of the magnetosphere. See http://www.imdb.com/title/tt0298814/)

People with pacemakers will all die! Pigeons will get confused and fly into buildings! Electrical Superstorms will destroy ancient Roman Colosseums!