An artist’s rendition of four identical spacecraft flying near the boundary of Earth’s magnetic field.
An artist’s rendition of four identical spacecraft flying near the boundary of Earth’s magnetic field.

Doubt over whether Earth’s poles will flip

A DEBATE is waging about the fate of the magnetic force that blankets the Earth and governs some of our most vital technology.

The Earth has a magnetic field which scientists believe is generated by motion in the planet's core. It's what gives us our north and south poles and powers our compasses.

We've known for more than a century that our planet's magnetic field has been weakening at a rate of about five per cent a century, prompting concerns that the Earth's magnetic poles could soon flip - an event that could have potentially disastrous results for life on Earth.

From the electrical grids that power our computers to the satellites that let us watch TV, many facets of our lives depend on the Earth's magnetic field. It also acts like an invisible force field protecting Earth from solar winds and harmful cosmic radiation.

But it's far from stable and every once in a while the poles reverse.

About 40,000 years ago, it underwent a dramatic "wobble", but didn't quite topple. But the ongoing weakening and in particular the expansion of a weak hole in the magnetic field in the South Atlantic known as the South Atlantic Anomaly (SAA), has led to concerns that a significant change could be afoot.

The last time the poles reversed was roughly 780,000 years ago and certain commentators have expressed concern that we could be heading for another flip in the not too distant future. Historically the magnetic north and south poles flip about every 300,000 years, so some say we're overdue.

However new research led by Richard Holme of Liverpool University in the UK shows that it might not be time to fret just yet.

One scientist thinks a pole reversal would leave some parts of the globe uninhabitable.
One scientist thinks a pole reversal would leave some parts of the globe uninhabitable.

'EXTREME EVENT' UNLIKELY

The paper published in the scientific journal Proceedings Of The National Academy Of Sciences titled "Earth's magnetic field is probably not reversing" has helped quieten some of the wilder speculation about this proposed doomsday scenario.

Based on data modelling, the researchers found two times in the Earth's geological history where its magnetic field looked similar to the way it does today and both times the poles didn't switch. Nor did they experience an excursion where they quickly snap to a different position.

"At earlier times ... the field is comparable to today's field, with an intensity structure similar to today's South Atlantic Anomaly (SAA); however, neither of these SAA-like fields develop into an excursion or reversal," the paper said.

"This suggests that the current weakened field will also recover without an extreme event such as an excursion or reversal."

Prof Holme said the results counteract the recent "speculation that we are about to experience a magnetic polar reversal or excursion," he said.

"By studying the two most recent excursion events, we show that neither bear resemblance to current changes in the geomagnetic field and therefore it is probably unlikely that such an event is about to happen."

The Northern Lights, or aurora borealis, is caused by charged particles from the Sun being captured by Earth’s magnetic field. Picture: James Woodend
The Northern Lights, or aurora borealis, is caused by charged particles from the Sun being captured by Earth’s magnetic field. Picture: James Woodend

Despite the limitations of the research due to data gaps, Sanja Panovska, a researcher at the German Research Centre for Geosciences who was not involved with the study, told Gizmodo it demonstrated that current signs don't necessarily point to anything unusual.

"The analysis shows that the magnetic field showed similar structures in the past that did not lead to an extreme event, so the South Atlantic Anomaly cannot be taken as an indication that we are in the early stages of such an event," she said.

WHAT'S ALL THE FUSS ABOUT?

Despite the latest findings, if the SAA persists and if the magnetic field continues to weaken, it could prove problematic for electrical grids which rely on the magnetic field or satellites passing overhead. In recent decades the SAA has thought to have caused computers to crash on space shuttles and the International Space Station.

The latest worry over the threat of a dramatic pole reversal was exacerbated by a book published by acclaimed science journalist Alanna Mitchell in January this year, The Spinning Magnet: The Electromagnetic Force That Created The Modern World - And Could Destroy It.

A widely cited extract of the book included a warning that it was "time to wake up to the dangers and start preparing" for a magnetic pole reversal.

However these processes unfold slowly and many scientists predict it may take thousands of years before Earth's magnetic field reverses again.

It's incontrovertible the poles will switch at some point, but the reality is that scientists simply don't have enough information right now to accurately predict when that might happen.