Shocking change in Earth’s core could alter everything we knew

A new study published in Nature Geoscience sheds light on what is happening deep beneath our feet in the Earth’s core. Many might remember learning about the inner and outer cores of the Earth, but research continues to figure out what exactly is going on thousands of miles below our planet’s crust.

What do changes in the core mean for life on Earth’s crust?

Researchers at the Department of Earth Sciences at the University of Southern California published their findings earlier this week, claiming that the “rotation rate and shape” of the inner core have not remained constant over the last few decades. Though we might not be able to notice up on the Earth’s crust, changes in the Earth’s core can impact the rotation of the entire planet and the geomagnetic plane that triggers a compass to move in certain directions.

“The inner core has been inferred to change its rotation rate or shape over years to decades since the discovery of temporal variability in seismic waves from repeating earthquakes that traveled through the inner core,” explained the researchers in the paper’s abstract. The study aimed to better understand the relationship between seismic activity and the inner core by examining earthquake waves picked up by two North American stations between 1991 and 2023. By comparing the records at these two stations, they found that between 2004 and 2008, one station had not recorded changes that the other had, meaning that their location and its relationship to certain parts of the core impacted the recordings. For the scientists, this led them to believe that the changes in the inner core that were being recorded were happening in what is referred to as the “shallow portion.” In other words, the rotation and shape of the core in that outer layer interact with the Earth’s other layers, which explains why differences are picked up by different seismic recorders.

Why are these findings so significant? Well, changes in the rotation of the inner core have the ability to alter the length of the day on Earth, meaning that a better understanding of the shape and rotation of the inner core is critical for scientists to be able to predict changes to the Earth’s rotation.

The new findings build on recent research

This study from researchers in Southern California follows previous work by other scholars published over the last five years.

The 2023 article published in Nature Geoscience by scientists from Peking University suggested that the Earth’s inner core—the spinning mass at the center of the planet—may have stopped rotating. Scientists had previously hypothesized that the planet’s outer layer spins at a different rate from the inner core, which is suspended within a layer of molten iron. The inner core’s relative speed is thought to play a role in maintaining the magnetic fields on Earth, but the new findings suggest that something is changing beneath our feet.

Read more: What do scientists say about Earth’s core is in a ‘Quite abnormal’ superionic state?

In 2024, another study was published in the journal by a larger research team, which included Dr. John Vidale—the lead author of the latest published study—demonstrating that the Earth’s core was functioning normally, directly contradicting findings from a 2023 study. However, this does not imply that scientists fully grasp the underlying mechanisms. Dr. Vidale and his team observed that while the Earth’s core has been slowing over the past few decades, they anticipate an increase in its spinning speed in the years and decades ahead. The researchers identified a 70-year cyclical pattern that the core follows, enabling more accurate projections of the core’s future velocity.

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