Jan 26, 2023 I Paul Seaburn

Earth’s Inner Core Has Paused Its Spinning and That May Not Be Good

Did you feel something? No? Did you feel nothing? That may be worse. A new study reveals that the Earth’s inner core – that hot ball of iron in its center – has stopped rotating and is in a ‘pause’ state. While ‘pause’ is a good state for your TV when you need to run to the bathroom, it sounds like a bad thing for the core of a planet where everything else is still spinning. Does the Earth’s core need a jumpstart? Does this affect time? Can science explain it? Are we in trouble? Let’s find out.

For those of you who slept through science class.

“We were quite surprised.”

That’s not necessarily a good thing to hear from scientists trying to figure out why something the size of Pluto which is right beneath our feet and affects life on our planet has suddenly stopped acting normally. In their new study, “Multidecadal variation of the Earth’s inner-core rotation” published in the journal Nature Geoscience, Yi Yang and Xiaodong Song, seismologists at Peking University in Beijing, reveal the challenge of explaining mysterious changes in something that is already a mystery – the inner core of the Earth. It turns out scientists have only known about the existence of the inner core since 1936 – thus disappointing young boys with shovels everywhere who dreamed of digging to the other side of the world. By studying how seismic waves from earthquakes travel through the crust, they determined that seismic waves traveling through the entire planet acted unexpectedly, and that anomaly was resolved nicely with the existence of what was eventually determined to be a solid iron ball about 1500 miles (2400 km) wide. That ball spins inside a layer of molten iron. As they interact, the density of the liquid iron changes and creates motions that maintain the Earth’s protective magnetic field. Unfortunately, that liquid shields the solid ball from scientists on the surface, making it difficult to determine why the core is spinning and how fast.

Xiaodong Song has been studying the core for some time. In 1996, he and seismologist Paul Richards of Columbia University proved the theory that the Earth’s inner core rotates separately from the rest of the planet – something which was predicted by a model of the Earth’s magnetic field. Since that time, scientists have argued how fast the inner core spins. Some believe it makes a complete revolution every 400 years, while others decided the spin is much slower - taking possibly 1,000 years or more to complete a revolution. Fortunately, Song has not lost interest in determining the core’s spin speed. More fortunately, he and other seismologists have continued to collect data on seismic waves as they pass through the center of the Earth. With new partner Yi Yang, Song analyzed looked at the difference in the waveform and travel time of seismic waves from near-identical earthquakes that have passed through the Earth’s inner core along similar paths since the 1960s. what they found was shocking.

“They found that since around 2009, paths that previously showed significant temporal variation have exhibited little change.”

“This globally consistent pattern suggests that the rotation of the inner core has recently been suspended.”

While they could have understood a change in the speed of the spin of the core – either a slowing down or even a speeding up - they did not expect a complete stop. Before you panic and start running to help the core start spinning again, scientists have known the Earth’s iron core speeds up and slows down. In fact, they have suspected that this occurs on a seven-decade cycle. In the 1970s, the seismic waves showed that inner core was spinning faster than the mantle. In the late 2000s, the waves showed a slowdown. But a compete pause? Like all good scientists, Yang and Song have a theory.

"We believe the inner core rotates, relative to the Earth's surface, back and forth, like a swing. One cycle of the swing is about seven decades."

So a ‘pause’ in the temporal variations in the Earth’s core just means the pendulum has swung to the end of a swing and is in that moment of suspension before swinging back in the other direction. That doesn’t mean it is about to change directions in relation to the outer part of the plant – now THAT would be disastrous. However, the discrepancy between the speeds has been shown to cause changes in geophysical observations on the Earth’s surface.

"It has effects on the magnetic field and the Earth's rotation, and perhaps the surface processes and climate. It may have a long-term effect (decades and centuries), but the effect on daily life is likely small."

That’s right – the pause in the core can affect the magnetic field, the length of a day and … that dreaded climate change. While it is “small,” small is a relative term when discussing something as big as the planet. And that’s not all. Yang told Salon that this seven decade swing in speeds affects things above and below the surface as well.

"Similar periodicity has already been found in other Earth layers, such as the outer core (from the magnetic field changes), mantle and crust (from the LOD variations), and the surface (from the global mean sea level rise and temperature)."

Are we spinning (or not spinning) out of control? 

If you’re worried about what this means for our future and that of the planet, you can take some comfort in the fact that many scientists disagree with – or at least question – this study. Lianxing Wen, a seismologist at Stony Brook University, is one.

"This study misinterprets the seismic signals that are caused by episodic changes of the Earth's inner core surface. (The claim that the inner core rotates independently of the surface)  provides an inconsistent explanation to the seismic data even if we assume it is true."

Song disagrees and offers a good news - bad news response.

“(It) won't affect our gas prices or winter storms. (But it impacts our) geomagnetic field, which shields us from solar winds, and length-of-day, which affects our GPS system."

Something to think about as you sing along to Carole King’s “I Feel the Earth Move.”

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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