Earth's Magnetic Field Due for a Flip?

Don't be surprised if at some point in your lifetime the Earth's magnetic field flips on its head, and all that was once north is now pointing due south, a new study says.

It may sounds strange, but Earth's magnetic field has in fact flipped many times throughout the planet's history - albeit not overnight. Its dipole magnetic field, like that of a bar magnet, remains about the same intensity for thousands to millions of years. Then, for some mysterious reason, it weakens and does a complete 180.

Now, a team from the University of California, Berkeley and their colleagues have shown that what presumably would take place over a few thousands years actually happened in less than 100 years - roughly a human lifetime - during the last magnetic reversal some 786,000 years ago.

"It's amazing how rapidly we see that reversal," UC Berkeley graduate student Courtney Sprain said in a statement. "The paleomagnetic data are very well done. This is one of the best records we have so far of what happens during a reversal and how quickly these reversals can happen."

Given this rapid role reversal, combined with evidence that the intensity of Earth's magnetic field is decreasing 10 times faster than normal, scientists are led to believe that the magnetic field will once again flip within a few thousand years. Not to worry though, the magnetic reversal may be a major planet-wide event driven by convection in Earth's iron core, but no catastrophes have occurred on our planet as a result, as far as geological records can tell.

The findings are based on measurements of the magnetic field alignment in layers of ancient lake sediments now exposed in the Sulmona basin of the Apennine Mountains east of Rome, Italy. They also used a technique called argon-argon dating, which is used to determine the age of rocks.

The sudden 180-degree flip, called the Matuyama-Brunhes transition, was preceded by a period of instability that spanned more than 6,000 years. Researchers worry that long periods of unstable magnetic behavior could result in genetic mutations in humans, or cancer, due to a weakening or temporary loss of the field. Whether or not the new finding spells trouble for modern civilization, it likely will help researchers understand how and why Earth's magnetic field episodically reverses polarity, researcher Paul Renne said.

The findings were published in Geophysical Journal International.