EARTH’S MAGNETIC NORTH POLE IS HURTLING TOWARDS SIBERIA, AND ONE DAY THE WHOLE FIELD IS GOING TO FLIP
Earth’s magnetic field is behaving strangely. In recent months, scientists discovered the magnetic north pole was moving far faster than expected—speeding away from the Canadian arctic and towards Siberia. The change in location was so significant that experts had to issue an unscheduled update to the World Magnetic Model —the large scale representation of the magnetic field, which is used extensively in navigation systems across the world.
What caused this unexpected change was not clear, although some scientists have since suggested it could be related to ‘geomagnetic jerks’—a phenomenon discovered in the 1970s, where the magnetic field accelerates abruptly at random intervals.
On top of this, a number of experts have said the magnetic field is due to reverse, meaning the magnetic north and south pole swap places. Intervals between the reversals are irregular, but generally happen a few times every million years. At present, it is thought Earth is "overdue" one.
In an email interview with Newsweek , Phil Livermore, Associate Professor of geophysics at the University of Leeds, U.K, spoke about what is going on with the magnetic field.
What is Earth’s magnetic field and what does it do?
Earth’s magnetic field surrounds our planet, acting as an invisible force field that shields life on Earth’s surface—including crucial electrical infrastructure such as satellites and power grids—from harmful radiation from the sun. Although the geomagnetic field is at least three billion years old, according to studies of ancient rocks, its structure has shown persistent fluctuations through time, most notably including global polarity reversals which have occurred hundreds of times during its history.
Many navigation systems ranging from defence systems to smartphone apps rely on accurate knowledge of the magnetic field to determine direction, underlining the importance of understanding how and why it changes.
Why does it move?
Earth’s magnetic field is generated within the Earth’s liquid interior by swirling motions of molten iron. Just like our changeable weather and climate driven by motion within our atmosphere, the magnetic field is constantly on the move. The dynamics of the core are very challenging to understand, principally because the core is separated from us on the Earth’s surface by the mantle, about 3,000 kilometers (1,864 miles) of solid rock. However, global networks of ground-based observatories and satellites measure changes in the magnetic field, which along with computer models of the core, give us insight into the dynamics at the heart of our planet.
How fast does the magnetic north pole normally move and how did this change?
The first expedition to find the north magnetic pole, where the magnetic field points vertically downwards, was undertaken by James Clark Ross in 1831. Subsequent expeditions, and global observations from both Earth’s surface and space, allow a reconstruction of the history of the north magnetic pole. Prior to 1990, the north magnetic pole moved at a sedate speed of approximately 0-15km/yr (0-9m/yr); but in the 1990s its speed dramatically increased to its present value of 50-60km/yr (31-37m/yr.)
The position of the north pole seems to be controlled by a tug of war between two patches of magnetic field: one under Siberia and one under Canada: weakening of the Canadian patch explains the acceleration of the pole.
What does this change have to do with geomagnetic jerks?
Geomagnetic jerks are a sudden alteration in the behaviour of the magnetic field as measured on Earth’s surface, specifically in its rate of change with time, and are often geographically localised. Jerks occur frequently, for example there have been recent jerks in 2007, 2011 and 2014. Although the north magnetic pole has also shown a recent change from its historical behaviour, its persistent speed over the last few decades means that it is not obviously connected with geomagnetic jerks.
When will the magnetic north pole get to Siberia and where will it go after that?
The north magnetic pole crossed the international date line in late 2017 and is now on the “other side” of the world from Canada, heading towards Siberia. If it continues along its current trajectory and speed, within two decades it will reach Siberia. Predicting the geomagnetic field is very difficult, however it is entirely possible that the magnetic pole may return to Canada in the future.
When will the magnetic field next flip? What happened last time it did?
The last global reversal, the Brunhes-Matuyama, occurred about 780,000 years ago, although a failed reversal, the Laschamp event, occurred around 41,000 years ago when the field temporarily reversed and rapidly switched back to its previous polarity.
Magnetic flips occur about three times per million years, which coupled with the current weakening trend of the global magnetic field by about 5 percent per century, has led to speculation that planet Earth may be headed for a reversal.
Life has clearly survived the many magnetic reversals, and indeed early humans successfully managed to live through the Laschamp event. It is unclear however how a globally changing magnetic field might impact animals with magnetoreception that they, for example, might use to navigate long distances during migration.
What are you working at the moment in relation to the magnetic field?
The trio of Swarm satellites are currently taking measurements from space, producing the best-ever survey of our changing planetary magnetic field. Understanding this rich and high resolution data set gives us an unprecedented opportunity to learn about the interior of our planet. One key challenge, which is becoming ever closer to our grasp, is to be able to model the changes we have seen over the last few decades.
If we can do this, then we may have a decent chance of accurately predicting what lies in store for Earth in the years to come.https://www.newsweek.com/earth-magnetic-field-flip-north-pole-moving-1412603
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