Earth's Changing Magnetic Field May Flip Over the Course of a Human Lifetime

What if all of the compasses in the world suddenly pointed south instead of north? Earth's magnetic field periodically flips over time and now, scientists have announced that it's possible for this change to occur over the course of a human lifetime--in less than 100 years.

"It's amazing how rapidly we see that reversal," said Courtney Sprain, one of the researchers, in a news release. "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."

A magnetic reversal is a planet-wide event that's driven by convection in the Earth's core. The last reversal occurred about 786,000 years ago, and there are no documented catastrophes associated with these reversals. Yet today, such a reversal could wreak havoc on our electrical grid, generating currents that could take it down.

In order to find out how quickly this reversal could occur, the scientists measured the magnetic field alignment in layers of ancient lake sediments. The lake sediments are interbedded wit hash layers erupted from the Roman volcanic province. The scientists measured the magnetic field directions frozen in the sediments and then used argon-argon dating to determine the age of the sediments.

In this case, the researchers were able to find out the date of the layer that showed the latest magnetic reversal, called the Matuyama-Brunhes transition. In fact, the date they found was far more precise than previous studies, and placed the reversal between 770,000 and 795,000 years ago.

"What's incredible is that you go from reverse polarity to a field that is normal with essentially nothing in between, which means it had to have happened very quickly, probably in less than 100 years," said Paul Renne, one of the researchers. "We don't know whether the next reversal will occur as suddenly as this one did, but we also don't know that it won't."

The findings reveal that this reversal has the potential to occur very quickly. This could, in turn, mean trouble for modern civilization and its technology. That said, the scientists plan to continue their studies in order to understand why and how Earth's magnetic field reverses its polarity.

The findings are published in Geophysical Journal International.