Earth's magnetic field could change 10 times faster than we thought, scientists say

Magnetic field shields us from harmful radiation and helps keep atmosphere in place, as well as being key to navigation

The Earth's magnetic field could change 10 times faster than previous thought, scientists have said.

Using computer simulation of the iron deep beneath our feet that influences how the magnetic field appears to us, they showed that it could move around much more quickly than we had realised.

The discovery could have important implications for our understanding of some of the most fundamental processes that power life on Earth: the magnetic field is not only used in compasses and for navigation, but helps protect us from radiation coming from space and keeps our atmosphere in place.

The magnetic field is generated and regulated by a swirling flow of molten metal that creates the Earth's outer core. As the liquid iron moves around, it creates electric currents that power the magnetic field that is used on the surface.

Scientists are nowadays able to measure and track the changes as the flowing iron move around and alters the field, using satellites and other technology. But it is more difficult to understand its movements in the past, since it changes on a much longer time-scale than our relatively very recent technology.

Attempts to understand the change through history has relied on much more imperfect data, such as using both natural and human-made evidence to make inferences about the magnetic fields through its long history. But that remains difficult and the accuracy of those techniques is disputed.

The new study instead used computer simulations to understand how the field could be generated, and gave it data that shows how the Earth's magnetic field may have changed over the last 10,000 years.

They found that the field changed in direction at speeds up to 10 times faster than even the fastest reported variations.

The fastest events happen when the magnetic field becomes weaker, which happens at times when the field has "flipped" or reversed polarity, or when it has moved away from the north or south poles.

At one time some 39,000 years ago, for instance, the direction of the field was moving about 2.5 degrees each year. That came relatively soon after the Earth's magnetic field flipped for a short period of time, known as the Laschamp excursion, some 41,000 years ago.

Scientists hope to further examine such simulations to understand whether such dramatic changes can happen at relatively stable times for the magnetic field, like those we are living through at the moment.

"We have very incomplete knowledge of our magnetic field prior to 400 years ago," said Chris Davies, from the University of Leeds, one of the leaders of the study. "Since these rapid changes represent some of the more extreme behaviour of the liquid core they could give important information about the behaviour of Earth's deep interior."