The Earth’s magnetic field flips, every few hundred thousand years or so on average, which means magnetic north becomes magnetic south and vice versa (the planet doesn’t actually turn upside down). New research suggests this change of direction can happen up to 10 times faster than previously thought.
That’s big news for scientists studying how the magnetic field shifts affect life on Earth, how our planet has evolved over time, and how we might be better able to predict the next reversal in the coming years.
Past palaeomagnetic studies have shown that the magnetic field could change direction at up to 1 degree a year, but the latest study suggests that movements of up to 10 degrees annually are possible.
That’s based on detailed computer simulations of the outer core made of nickel and iron some 2,800 kilometres (1,740 miles) below Earth’s surface, which controls our 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 behaviour of the liquid core, they could give important information about the behaviour of Earth’s deep interior.”
Davies and his colleague Catherine Constable from the University of California San Diego combined their computer modelling with a recently published timeline of Earth’s magnetic field over the past 100,000 years, and found a close match between the other study and their own predictions.
Changes in our planet’s magnetic field leave traces in sediment, lava flows, and even human-made objects, though some educated guesswork is still required when it comes to working out how it’s shifting and over what period of time.