Earth’s Inner Core Might Be Slowing Down

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Volunteer Writer: Mckenzie Ferrari


A study published on Jan 23rd, 2023, in Nature Geoscience led by Peking University researchers Yi Yang and Xiaodong Song claims that the Earth’s inner core may be slowing down and soon reverse direction.

Earth itself is made up of multiple layers: the inner core, outer core, mantle, and crust — which is where humans reside. The inner core is believed to be composed of primarily solid iron, whereas the outer core is a hot layer of metal liquid. The mantle and crust are primarily solid.

This configuration — of solid, liquid, then solid — allows the inner core to rotate freely from the planet’s mantle and crust.

Since Earth’s inner core is impossible to observe first-hand, scientists record seismic data from earthquakes to learn about the core. This is how the Earth’s inner core was first discovered in 1936.

Yang and Song analyzed past earthquake data and compared seismic activity from 1964 to the 1990s. Their findings suggest that the rotation rate of the inner core has recently slowed down. 

The inner core had previously been rotating faster than the surface of the Earth.

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The authors additionally hypothesize that the inner core’s rotation speed oscillates, or fluctuates, over a period of 70 years. However, another previous study from 2022 claims a period of just 6 years

But, more earthquakes and recorded seismic activity will be needed to clarify the actual time period of oscillation of the Earth’s inner core.

Why is oscillation of the Earth’s inner core important?

Oscillations of Earth’s inner core are believed to be linked to the Earth’s magnetic field and minor fluctuations in the length of a day over time. These changes in the length of the day are minor — usually only ± 0.2 seconds over the course of six years.

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Should we be worried about the inner core slowing down?

No. The naturally fluctuating processes and dynamics occurring under Earth’s surface are vital to life itself. Without protection from Earth’s magnetic field, cosmic radiation from the Sun would pelt our planet, making Earth uninhabitable.


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