What if the Earth’s magnetic field were to flip? This would mean that the north and south poles would be ‘switched’ into each other’s places. Well, surprise, surprise: this has occasionally happened in the past, and can happen yet again, earlier than we would have thought.
The dipole magnetic field of our planet remains about the same intensity for long periods of time. But, from time to time, it might also weaken, and reverse direction. Why does this happen has not been clearly elucidated.
Magnetic reversal occurring in less than 100-years’ time
While it is conventionally thought that the reversal process is done in thousands to millions of years, a team of scientists has shown that the last instance of the magnetic reversal occurred really fast, in less than 100 years.
“It’s amazing how rapidly we see that reversal,” said UC Berkeley graduate student Courtney Sprain, who is a co-author of the new research work.
Commenting on their results, Sprain said: “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.”
The scientific paper will be published in the Geophysical Journal International next month, though it is already available online.
Recently, it was suggested that the decrease in intensity of the Earth’s magnetic field is decreasing much faster than usual. Some physicists have therefore forecast the next reversal to happen in a time period of just several thousand years.
The implications of the magnetic reversal
The magnetic field generated by our planet provides great protection to its inhabitants against the harmful solar and cosmic rays. The latter might cause serious diseases entailing genetic mutations. If the field were to weaken or to temporarily ‘disappear’, the rate of cancer, for example, might increase.
Also, if the reversal were to be preceded by instances of unstable magnetism, life on Earth might be endangered.
Time of the last reversal estimated
The researchers of the new study focused on layers of ancient lake sediments in the Sulmona basin in Italy. The sediments consist of ash layers emitted from the Roman volcanic province. The magnetic field alignment in these layers was measured. The age of the ash layers was also determined using argon-argon dating, in order to know approximately the time when the last reversal happened: the reversal was concluded to have occurred 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 Renne. “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 results also revealed that the sudden flip happened after a period of instability that spanned over thousands of years.
The scientists are positive that the results of their study will potentially be of great help in finding out the reason behind the Earth’s polarity reversal.