Our planet features two magnetic poles that change wildly; this does not correspond with its geodetic (or geographic) poles which move more gradually over centuries.
Molten iron in our core forms poles that move independently of each other; throughout history they've shifted, swapped places, and even reversed themselves.
What Causes the Earth?s Magnetic Pole to Shift?
Every several hundred thousand years, Earth's magnetic north and south poles alternate. This phenomenon, dubbed geomagnetic reversal, occurs as magnets at its core weaken, shift, stabilize and eventually reverse direction. Scientists can track when and how this happens thanks to magnetic fields recorded by ocean sediments, Antarctic ice cores, lava flows or rocks with strong magnetism tracing back to Earth's molten iron core which produces these fields.
Due to our planet's ever-swirling core of molten iron, its magnetic poles are constantly shifting as well. Their locations may wander independently from each other and even completely change once every million years - something which affects not only people with compasses but also animals such as birds, fish and sea turtles who use internal compasses for navigation.
Recent decades have witnessed an unusually rapid movement of the magnetic north pole from Canada towards Siberia. Experts who track these changes through Nature journal are scrambling to keep up with it; doing so means updating their map of world's magnetic poles early next year. NPR's Ari Shapiro sits down with Nature reporter Alexandra Witze to understand why our magnetic poles are shifting, what might cause reversals, and whether these signs point towards imminent change.
Scientists have been tracking our magnetic north pole since it was first observed by British polar explorer James Clark Ross near Boothia Peninsula in Canada's Nunavut territory back in 1831. Up until recently, its movement had been relatively moderate at approximately 9 kilometers per year.
Geodynamos, or unpredictably swirling currents of molten iron in our planet's core, create an unpredictable current known as geodynamo that generates magnetic fields for navigation or viewing Aurora Borealis. However, its effectiveness may be altered by factors like spin affect on core-molten iron ratio, irregularities where core and mantle meet and other factors that impact it.
How It Affects Us
The Earth has two poles, geographic north and south. Additionally, its magnetic north and south poles also define where compass points. This occurs because its core contains electric current that generates magnetic fields around it that can be affected by moving molten iron in its core - this has resulted in its magnetic fields weakening, shifting, stabilizing or even reversing in history; fossil records show that last time was 770,000 years ago and experts now suspect another one is long overdue!
Reversals occur when the magnetic north and south poles change places. As this happens, currents that make up the magnetic field will shuffle around, shifting currents that create it; and, the magnetosphere, which protects us from cosmic rays and charged solar particles will become disorganized - leading to its gradual weakening over hundreds to thousands of years.
Scientists don't fully understand why the poles move. A variety of factors could play a part in this phenomenon, such as changes to how quickly molten iron spins in its core or irregularities at the core-mantle boundary and changes to outer layers such as earthquakes.
Over time, the rate at which the magnetic north pole has shifted has steadily increased over time. From nine miles per year in earlier decades to up to 37 miles annually in recent decades - meaning navigation systems and technologies that rely on its location will need to be updated more frequently.
Research on this pole shift indicates that its location is determined largely by a tug-of-war between two large blobs of molten iron at the core-mantle boundary beneath Canada and Siberia that have fluctuated in size over recent decades, leading to an ever increasing shift in which Canada gradually loses ground against Siberia as the north magnetic pole shifts toward Siberia.
What Will Happen if the Pole Flips?
Magnetic poles differ from their geographic counterparts in that they can drift over time - this phenomenon known as "polar wander". Scientists are currently developing a model to predict this movement of the magnetic north pole which has recently moved toward Siberia at an alarming rate; should this trend continue, its reverse could occur sooner than anticipated.
This phenomenon is caused by the whirling motion of superheated iron in Earth's core, creating magnetic fields. Convection occurs as hotter, less dense matter rises to the surface before cooling again causing currents to circulate within it - this process causes magnetic poles to migrate and eventually switch places; making what was once North become South and vice versa over time and up to 28,000 years.
As magnetic poles reorient themselves, their strength weakens over time - diminishing our protection from cosmic rays and charged solar particles as a result. This natural process explains why there hasn't been a complete reversal since 41,000 years ago.
NASA estimates that the poles should return to their original positions sometime between now and 2040; until then, be careful when using your compass.
People fear a magnetic pole reversal will have catastrophic repercussions, but in truth it likely won't affect us significantly. No evidence suggests past reversals caused mass extinctions or major disasters; our compasses will simply become increasingly inaccurate and we may need to purchase new ones.
Due to an unexpected "blip" in Earth's core convection patterns, magnetic poles have been shifting faster than usual in recent months. Before this "blip", Canada was home to the North Pole while now it's rapidly approaching Siberia. While this doesn't portend a pole reversal event anytime soon, navigation systems and smartphones may experience disruption.
What Can We Do About It
Scientists don't know exactly why the poles change position, but they know it occurs regularly in cycles. Major reversals have occurred over a span of hundreds of thousands of years in some instances. When the poles do flip, however, this causes a weakening in magnetic fields which could affect technologies like satellites operating in low Earth orbit - according to Live Science reports.
Scientists have closely observed the path taken by the north magnetic pole since its discovery in 1831, tracking its movements with precision. While its speed varies over time, recently its speed has dramatically increased from around 9 miles a year to 50 miles annually - prompting navigation systems and smartphones using it as their mapping source to update their software accordingly. This rapid shift requires regular updates to remain effective.
Researchers from Leeds and Denmark, led by Technical University of Denmark's Technical University of Denmark have come up with an explanation for why Earth's magnetic pole is moving faster. According to them, this may be caused by two blobs of negative magnetic flux near Earth's outer mantle that compete to determine where its north magnetic pole should sit. They used 20 years' worth of satellite data gathered through ESA?s Swarm mission to observe changes in shape of magnetic field over this timeframe.
Researchers then developed a model that predicted how the pole would move in the future. Their simulation depicted it continuing its rapid march towards Russia before eventually slowing and eventually stopping somewhere in Siberia.
Although rapid magnetic pole shifts may seem alarming, this does not indicate imminent doom for our planet. Pole reversals do not happen overnight and their signs have left fossilized records that allow paleomagnetists to determine how continents moved during them which offers key insights into plate tectonics.
Last time around was 780,000 years ago and did not lead to any noticeable climate changes; however, smaller events may happen more frequently, and are estimated to occur once every 100,000 years or so.
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