The magnetic field of the Earth switches every few hundred thousand years on average, as we already know, which means that the magnetic north of the planet transforms into the magnetic south and vice versa. Now, a new study found that the change of direction can take place up to ten times faster than scientists earlier estimated.
This is good news for researchers observing the way the magnetic field shifts impact life on Earth, how our planet has developed throughout time, and how we might be able to predict the next flip in the future.
Previous palaeomagnetic research has shown that the magnetic field could alter its direction at up to one degree a year, but the most recent analyses imply that movements of about ten degrees annually are possible. That is based on precise computer simulations of the outer nucleus composed of nickel and iron about 2,800 kilometers (1,740 miles) underneath Earth’s surface, which control the magnetic field.
“We have very incomplete knowledge of our magnetic field prior to 400 years ago,” says geophysicist Chris Davies from the University of Leeds in the UK. “Since these rapid changes represent some of the more extreme behavior of the liquid core, they could give important information about the behavior of Earth’s deep interior.”
Davies and his colleague Catherine Constable from the University of California, San Diego, compared and merged their computer modeling with a recently published timeline of the planet’s magnetic field over the last 100,000 years, and found a good fit between the other research and their own predictions.
Changes in Earth’s magnetic field leave prints in sediment, lava flows, and even human-made structures, but some guesswork is still needed when it comes to figuring out how it’s flipping and throughout what period of time.
The Poles are Always Wandering About
Faster alternations in direction seem to match with a local weakening of the magnetic field, the new study says. One shift was studied more: a movement of 2.5 degrees per year about 39,000 years ago, after the latest Laschamp excursion flip, when the planet’s magnetic field was weakened around the west coast of Central America.
“Understanding whether computer simulations of the magnetic field accurately reflect the physical behavior of the geomagnetic field as inferred from geological records can be very challenging,” says Constable. “But in this case, we have been able to show excellent agreement in both the rates of change and general location of the most extreme events across a range of computer simulations.”
Earth’s magnetic field helps us travel with a compass or newer technology, and it also protects us from the effects of space and solar radiation. The magnetic poles are always moving about, even though most people do not know it.
Understanding more about the way these flips take place, as well as at what speed, is crucial for a number of things, including reconfiguring satellites to manage the changes in radiation exposure that might result from a change of the field.
“Further study of the evolving dynamics in these simulations offers a useful strategy for documenting how such rapid changes occur and whether they are also found during times of stable magnetic polarity like what we are experiencing today,” says Constable.
A paper detailing the study has been published in Nature Communications.